/* SCC value numbering for trees Copyright (C) 2006, 2007 Free Software Foundation, Inc. Contributed by Daniel Berlin This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see . */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "ggc.h" #include "tree.h" #include "basic-block.h" #include "diagnostic.h" #include "tree-inline.h" #include "tree-flow.h" #include "tree-gimple.h" #include "tree-dump.h" #include "timevar.h" #include "fibheap.h" #include "hashtab.h" #include "tree-iterator.h" #include "real.h" #include "alloc-pool.h" #include "tree-pass.h" #include "flags.h" #include "bitmap.h" #include "langhooks.h" #include "cfgloop.h" #include "params.h" #include "tree-ssa-propagate.h" #include "tree-ssa-sccvn.h" /* This algorithm is based on the SCC algorithm presented by Keith Cooper and L. Taylor Simpson in "SCC-Based Value numbering" (http://citeseer.ist.psu.edu/41805.html). In straight line code, it is equivalent to a regular hash based value numbering that is performed in reverse postorder. For code with cycles, there are two alternatives, both of which require keeping the hashtables separate from the actual list of value numbers for SSA names. 1. Iterate value numbering in an RPO walk of the blocks, removing all the entries from the hashtable after each iteration (but keeping the SSA name->value number mapping between iterations). Iterate until it does not change. 2. Perform value numbering as part of an SCC walk on the SSA graph, iterating only the cycles in the SSA graph until they do not change (using a separate, optimistic hashtable for value numbering the SCC operands). The second is not just faster in practice (because most SSA graph cycles do not involve all the variables in the graph), it also has some nice properties. One of these nice properties is that when we pop an SCC off the stack, we are guaranteed to have processed all the operands coming from *outside of that SCC*, so we do not need to do anything special to ensure they have value numbers. Another nice property is that the SCC walk is done as part of a DFS of the SSA graph, which makes it easy to perform combining and simplifying operations at the same time. The code below is deliberately written in a way that makes it easy to separate the SCC walk from the other work it does. In order to propagate constants through the code, we track which expressions contain constants, and use those while folding. In theory, we could also track expressions whose value numbers are replaced, in case we end up folding based on expression identities. In order to value number memory, we assign value numbers to vuses. This enables us to note that, for example, stores to the same address of the same value from the same starting memory states are equivalent. TODO: 1. We can iterate only the changing portions of the SCC's, but I have not seen an SCC big enough for this to be a win. 2. If you differentiate between phi nodes for loops and phi nodes for if-then-else, you can properly consider phi nodes in different blocks for equivalence. 3. We could value number vuses in more cases, particularly, whole structure copies. */ /* The set of hashtables and alloc_pool's for their items. */ typedef struct vn_tables_s { htab_t unary; htab_t binary; htab_t phis; htab_t references; alloc_pool unary_op_pool; alloc_pool binary_op_pool; alloc_pool phis_pool; alloc_pool references_pool; } *vn_tables_t; /* Binary operations in the hashtable consist of two operands, an opcode, and a type. Result is the value number of the operation, and hashcode is stored to avoid having to calculate it repeatedly. */ typedef struct vn_binary_op_s { enum tree_code opcode; hashval_t hashcode; tree type; tree op0; tree op1; tree result; } *vn_binary_op_t; typedef const struct vn_binary_op_s *const_vn_binary_op_t; /* Unary operations in the hashtable consist of a single operand, an opcode, and a type. Result is the value number of the operation, and hashcode is stored to avoid having to calculate it repeatedly. */ typedef struct vn_unary_op_s { enum tree_code opcode; hashval_t hashcode; tree type; tree op0; tree result; } *vn_unary_op_t; typedef const struct vn_unary_op_s *const_vn_unary_op_t; /* Phi nodes in the hashtable consist of their non-VN_TOP phi arguments, and the basic block the phi is in. Result is the value number of the operation, and hashcode is stored to avoid having to calculate it repeatedly. Phi nodes not in the same block are never considered equivalent. */ typedef struct vn_phi_s { VEC (tree, heap) *phiargs; basic_block block; hashval_t hashcode; tree result; } *vn_phi_t; typedef const struct vn_phi_s *const_vn_phi_t; /* Reference operands only exist in reference operations structures. They consist of an opcode, type, and some number of operands. For a given opcode, some, all, or none of the operands may be used. The operands are there to store the information that makes up the portion of the addressing calculation that opcode performs. */ typedef struct vn_reference_op_struct { enum tree_code opcode; tree type; tree op0; tree op1; tree op2; } vn_reference_op_s; typedef vn_reference_op_s *vn_reference_op_t; typedef const vn_reference_op_s *const_vn_reference_op_t; DEF_VEC_O(vn_reference_op_s); DEF_VEC_ALLOC_O(vn_reference_op_s, heap); /* A reference operation in the hashtable is representation as a collection of vuses, representing the memory state at the time of the operation, and a collection of operands that make up the addressing calculation. If two vn_reference_t's have the same set of operands, they access the same memory location. We also store the resulting value number, and the hashcode. The vuses are always stored in order sorted by ssa name version. */ typedef struct vn_reference_s { VEC (tree, gc) *vuses; VEC (vn_reference_op_s, heap) *operands; hashval_t hashcode; tree result; } *vn_reference_t; typedef const struct vn_reference_s *const_vn_reference_t; /* Valid hashtables storing information we have proven to be correct. */ static vn_tables_t valid_info; /* Optimistic hashtables storing information we are making assumptions about during iterations. */ static vn_tables_t optimistic_info; /* PRE hashtables storing information about mapping from expressions to value handles. */ static vn_tables_t pre_info; /* Pointer to the set of hashtables that is currently being used. Should always point to either the optimistic_info, or the valid_info. */ static vn_tables_t current_info; /* Reverse post order index for each basic block. */ static int *rpo_numbers; #define SSA_VAL(x) (VN_INFO ((x))->valnum) /* This represents the top of the VN lattice, which is the universal value. */ tree VN_TOP; /* Next DFS number and the stack for strongly connected component detection. */ static unsigned int next_dfs_num; static VEC (tree, heap) *sccstack; DEF_VEC_P(vn_ssa_aux_t); DEF_VEC_ALLOC_P(vn_ssa_aux_t, heap); /* Table of vn_ssa_aux_t's, one per ssa_name. */ static VEC (vn_ssa_aux_t, heap) *vn_ssa_aux_table; /* Return the value numbering information for a given SSA name. */ vn_ssa_aux_t VN_INFO (tree name) { return VEC_index (vn_ssa_aux_t, vn_ssa_aux_table, SSA_NAME_VERSION (name)); } /* Set the value numbering info for a given SSA name to a given value. */ static inline void VN_INFO_SET (tree name, vn_ssa_aux_t value) { VEC_replace (vn_ssa_aux_t, vn_ssa_aux_table, SSA_NAME_VERSION (name), value); } /* Get the value numbering info for a given SSA name, creating it if it does not exist. */ vn_ssa_aux_t VN_INFO_GET (tree name) { vn_ssa_aux_t newinfo = XCNEW (struct vn_ssa_aux); if (SSA_NAME_VERSION (name) >= VEC_length (vn_ssa_aux_t, vn_ssa_aux_table)) VEC_safe_grow (vn_ssa_aux_t, heap, vn_ssa_aux_table, SSA_NAME_VERSION (name) + 1); VEC_replace (vn_ssa_aux_t, vn_ssa_aux_table, SSA_NAME_VERSION (name), newinfo); return newinfo; } /* Free a phi operation structure VP. */ static void free_phi (void *vp) { vn_phi_t phi = vp; VEC_free (tree, heap, phi->phiargs); } /* Free a reference operation structure VP. */ static void free_reference (void *vp) { vn_reference_t vr = vp; VEC_free (vn_reference_op_s, heap, vr->operands); } /* Compare two reference operands P1 and P2 for equality. return true if they are equal, and false otherwise. */ static int vn_reference_op_eq (const void *p1, const void *p2) { const_vn_reference_op_t const vro1 = (const_vn_reference_op_t) p1; const_vn_reference_op_t const vro2 = (const_vn_reference_op_t) p2; return vro1->opcode == vro2->opcode && vro1->type == vro2->type && expressions_equal_p (vro1->op0, vro2->op0) && expressions_equal_p (vro1->op1, vro2->op1) && expressions_equal_p (vro1->op2, vro2->op2); } /* Compute the hash for a reference operand VRO1 */ static hashval_t vn_reference_op_compute_hash (const vn_reference_op_t vro1) { return iterative_hash_expr (vro1->op0, vro1->opcode) + iterative_hash_expr (vro1->op1, vro1->opcode) + iterative_hash_expr (vro1->op2, vro1->opcode); } /* Return the hashcode for a given reference operation P1. */ static hashval_t vn_reference_hash (const void *p1) { const_vn_reference_t const vr1 = (const_vn_reference_t) p1; return vr1->hashcode; } /* Compute a hash for the reference operation VR1 and return it. */ static inline hashval_t vn_reference_compute_hash (const vn_reference_t vr1) { hashval_t result = 0; tree v; int i; vn_reference_op_t vro; for (i = 0; VEC_iterate (tree, vr1->vuses, i, v); i++) result += iterative_hash_expr (v, 0); for (i = 0; VEC_iterate (vn_reference_op_s, vr1->operands, i, vro); i++) result += vn_reference_op_compute_hash (vro); return result; } /* Return true if reference operations P1 and P2 are equivalent. This means they have the same set of operands and vuses. */ static int vn_reference_eq (const void *p1, const void *p2) { tree v; int i; vn_reference_op_t vro; const_vn_reference_t const vr1 = (const_vn_reference_t) p1; const_vn_reference_t const vr2 = (const_vn_reference_t) p2; if (vr1->vuses == vr2->vuses && vr1->operands == vr2->operands) return true; /* Impossible for them to be equivalent if they have different number of vuses. */ if (VEC_length (tree, vr1->vuses) != VEC_length (tree, vr2->vuses)) return false; /* We require that address operands be canonicalized in a way that two memory references will have the same operands if they are equivalent. */ if (VEC_length (vn_reference_op_s, vr1->operands) != VEC_length (vn_reference_op_s, vr2->operands)) return false; /* The memory state is more often different than the address of the store/load, so check it first. */ for (i = 0; VEC_iterate (tree, vr1->vuses, i, v); i++) { if (VEC_index (tree, vr2->vuses, i) != v) return false; } for (i = 0; VEC_iterate (vn_reference_op_s, vr1->operands, i, vro); i++) { if (!vn_reference_op_eq (VEC_index (vn_reference_op_s, vr2->operands, i), vro)) return false; } return true; } /* Place the vuses from STMT into *result */ static inline void vuses_to_vec (tree stmt, VEC (tree, gc) **result) { ssa_op_iter iter; tree vuse; if (!stmt) return; VEC_reserve_exact (tree, gc, *result, num_ssa_operands (stmt, SSA_OP_VIRTUAL_USES)); FOR_EACH_SSA_TREE_OPERAND (vuse, stmt, iter, SSA_OP_VIRTUAL_USES) VEC_quick_push (tree, *result, vuse); } /* Copy the VUSE names in STMT into a vector, and return the vector. */ VEC (tree, gc) * copy_vuses_from_stmt (tree stmt) { VEC (tree, gc) *vuses = NULL; vuses_to_vec (stmt, &vuses); return vuses; } /* Place the vdefs from STMT into *result */ static inline void vdefs_to_vec (tree stmt, VEC (tree, gc) **result) { ssa_op_iter iter; tree vdef; if (!stmt) return; *result = VEC_alloc (tree, gc, num_ssa_operands (stmt, SSA_OP_VIRTUAL_DEFS)); FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, iter, SSA_OP_VIRTUAL_DEFS) VEC_quick_push (tree, *result, vdef); } /* Copy the names of vdef results in STMT into a vector, and return the vector. */ static VEC (tree, gc) * copy_vdefs_from_stmt (tree stmt) { VEC (tree, gc) *vdefs = NULL; vdefs_to_vec (stmt, &vdefs); return vdefs; } /* Place for shared_v{uses/defs}_from_stmt to shove vuses/vdefs. */ static VEC (tree, gc) *shared_lookup_vops; /* Copy the virtual uses from STMT into SHARED_LOOKUP_VOPS. This function will overwrite the current SHARED_LOOKUP_VOPS variable. */ VEC (tree, gc) * shared_vuses_from_stmt (tree stmt) { VEC_truncate (tree, shared_lookup_vops, 0); vuses_to_vec (stmt, &shared_lookup_vops); return shared_lookup_vops; } /* Copy the operations present in load/store/call REF into RESULT, a vector of vn_reference_op_s's. */ static void copy_reference_ops_from_ref (tree ref, VEC(vn_reference_op_s, heap) **result) { /* Calls are different from all other reference operations. */ if (TREE_CODE (ref) == CALL_EXPR) { vn_reference_op_s temp; tree callfn; call_expr_arg_iterator iter; tree callarg; /* Copy the call_expr opcode, type, function being called, and arguments. */ memset (&temp, 0, sizeof (temp)); temp.type = TREE_TYPE (ref); temp.opcode = CALL_EXPR; VEC_safe_push (vn_reference_op_s, heap, *result, &temp); callfn = get_callee_fndecl (ref); if (!callfn) callfn = CALL_EXPR_FN (ref); temp.type = TREE_TYPE (callfn); temp.opcode = TREE_CODE (callfn); temp.op0 = callfn; VEC_safe_push (vn_reference_op_s, heap, *result, &temp); FOR_EACH_CALL_EXPR_ARG (callarg, iter, ref) { memset (&temp, 0, sizeof (temp)); temp.type = TREE_TYPE (callarg); temp.opcode = TREE_CODE (callarg); temp.op0 = callarg; VEC_safe_push (vn_reference_op_s, heap, *result, &temp); } return; } /* For non-calls, store the information that makes up the address. */ while (ref) { vn_reference_op_s temp; memset (&temp, 0, sizeof (temp)); temp.type = TREE_TYPE (ref); temp.opcode = TREE_CODE (ref); switch (temp.opcode) { case ALIGN_INDIRECT_REF: case MISALIGNED_INDIRECT_REF: case INDIRECT_REF: /* The only operand is the address, which gets its own vn_reference_op_s structure. */ break; case BIT_FIELD_REF: /* Record bits and position. */ temp.op0 = TREE_OPERAND (ref, 1); temp.op1 = TREE_OPERAND (ref, 2); break; case COMPONENT_REF: /* Record field as operand. */ temp.op0 = TREE_OPERAND (ref, 1); break; case ARRAY_RANGE_REF: case ARRAY_REF: /* Record index as operand. */ temp.op0 = TREE_OPERAND (ref, 1); temp.op1 = TREE_OPERAND (ref, 3); break; case STRING_CST: case INTEGER_CST: case COMPLEX_CST: case VECTOR_CST: case REAL_CST: case CONSTRUCTOR: case VALUE_HANDLE: case VAR_DECL: case PARM_DECL: case CONST_DECL: case RESULT_DECL: case SSA_NAME: temp.op0 = ref; break; /* These are only interesting for their operands, their existence, and their type. They will never be the last ref in the chain of references (IE they require an operand), so we don't have to put anything for op* as it will be handled by the iteration */ case IMAGPART_EXPR: case REALPART_EXPR: case VIEW_CONVERT_EXPR: case ADDR_EXPR: break; default: gcc_unreachable (); } VEC_safe_push (vn_reference_op_s, heap, *result, &temp); if (REFERENCE_CLASS_P (ref) || TREE_CODE (ref) == ADDR_EXPR) ref = TREE_OPERAND (ref, 0); else ref = NULL_TREE; } } /* Create a vector of vn_reference_op_s structures from REF, a REFERENCE_CLASS_P tree. The vector is not shared. */ static VEC(vn_reference_op_s, heap) * create_reference_ops_from_ref (tree ref) { VEC (vn_reference_op_s, heap) *result = NULL; copy_reference_ops_from_ref (ref, &result); return result; } static VEC(vn_reference_op_s, heap) *shared_lookup_references; /* Create a vector of vn_reference_op_s structures from REF, a REFERENCE_CLASS_P tree. The vector is shared among all callers of this function. */ static VEC(vn_reference_op_s, heap) * shared_reference_ops_from_ref (tree ref) { if (!ref) return NULL; VEC_truncate (vn_reference_op_s, shared_lookup_references, 0); copy_reference_ops_from_ref (ref, &shared_lookup_references); return shared_lookup_references; } /* Transform any SSA_NAME's in a vector of vn_reference_op_s structures into their value numbers. This is done in-place, and the vector passed in is returned. */ static VEC (vn_reference_op_s, heap) * valueize_refs (VEC (vn_reference_op_s, heap) *orig) { vn_reference_op_t vro; int i; for (i = 0; VEC_iterate (vn_reference_op_s, orig, i, vro); i++) { if (vro->opcode == SSA_NAME || (vro->op0 && TREE_CODE (vro->op0) == SSA_NAME)) vro->op0 = SSA_VAL (vro->op0); } return orig; } /* Transform any SSA_NAME's in ORIG, a vector of vuse trees, into their value numbers. This is done in-place, and the vector passed in is returned. */ static VEC (tree, gc) * valueize_vuses (VEC (tree, gc) *orig) { bool made_replacement = false; tree vuse; int i; for (i = 0; VEC_iterate (tree, orig, i, vuse); i++) { if (vuse != SSA_VAL (vuse)) { made_replacement = true; VEC_replace (tree, orig, i, SSA_VAL (vuse)); } } if (made_replacement && VEC_length (tree, orig) > 1) sort_vuses (orig); return orig; } /* Lookup OP in the current hash table, and return the resulting value number if it exists in the hash table. Return NULL_TREE if it does not exist in the hash table. */ tree vn_reference_lookup (tree op, VEC (tree, gc) *vuses) { void **slot; struct vn_reference_s vr1; vr1.vuses = valueize_vuses (vuses); vr1.operands = valueize_refs (shared_reference_ops_from_ref (op)); vr1.hashcode = vn_reference_compute_hash (&vr1); slot = htab_find_slot_with_hash (current_info->references, &vr1, vr1.hashcode, NO_INSERT); if (!slot && current_info == optimistic_info) slot = htab_find_slot_with_hash (valid_info->references, &vr1, vr1.hashcode, NO_INSERT); if (!slot) return NULL_TREE; return ((vn_reference_t)*slot)->result; } /* Insert OP into the current hash table with a value number of RESULT. */ void vn_reference_insert (tree op, tree result, VEC (tree, gc) *vuses) { void **slot; vn_reference_t vr1; vr1 = (vn_reference_t) pool_alloc (current_info->references_pool); vr1->vuses = valueize_vuses (vuses); vr1->operands = valueize_refs (create_reference_ops_from_ref (op)); vr1->hashcode = vn_reference_compute_hash (vr1); vr1->result = TREE_CODE (result) == SSA_NAME ? SSA_VAL (result) : result; slot = htab_find_slot_with_hash (current_info->references, vr1, vr1->hashcode, INSERT); /* Because we lookup stores using vuses, and value number failures using the vdefs (see visit_reference_op_store for how and why), it's possible that on failure we may try to insert an already inserted store. This is not wrong, there is no ssa name for a store that we could use as a differentiator anyway. Thus, unlike the other lookup functions, you cannot gcc_assert (!*slot) here. */ /* But free the old slot in case of a collision. */ if (*slot) free_reference (*slot); *slot = vr1; } /* Return the stored hashcode for a unary operation. */ static hashval_t vn_unary_op_hash (const void *p1) { const_vn_unary_op_t const vuo1 = (const_vn_unary_op_t) p1; return vuo1->hashcode; } /* Hash a unary operation P1 and return the result. */ static inline hashval_t vn_unary_op_compute_hash (const vn_unary_op_t vuo1) { return iterative_hash_expr (vuo1->op0, vuo1->opcode); } /* Return true if P1 and P2, two unary operations, are equivalent. */ static int vn_unary_op_eq (const void *p1, const void *p2) { const_vn_unary_op_t const vuo1 = (const_vn_unary_op_t) p1; const_vn_unary_op_t const vuo2 = (const_vn_unary_op_t) p2; return vuo1->opcode == vuo2->opcode && vuo1->type == vuo2->type && expressions_equal_p (vuo1->op0, vuo2->op0); } /* Lookup OP in the current hash table, and return the resulting value number if it exists in the hash table. Return NULL_TREE if it does not exist in the hash table. */ tree vn_unary_op_lookup (tree op) { void **slot; struct vn_unary_op_s vuo1; vuo1.opcode = TREE_CODE (op); vuo1.type = TREE_TYPE (op); vuo1.op0 = TREE_OPERAND (op, 0); if (TREE_CODE (vuo1.op0) == SSA_NAME) vuo1.op0 = SSA_VAL (vuo1.op0); vuo1.hashcode = vn_unary_op_compute_hash (&vuo1); slot = htab_find_slot_with_hash (current_info->unary, &vuo1, vuo1.hashcode, NO_INSERT); if (!slot && current_info == optimistic_info) slot = htab_find_slot_with_hash (valid_info->unary, &vuo1, vuo1.hashcode, NO_INSERT); if (!slot) return NULL_TREE; return ((vn_unary_op_t)*slot)->result; } /* Insert OP into the current hash table with a value number of RESULT. */ void vn_unary_op_insert (tree op, tree result) { void **slot; vn_unary_op_t vuo1 = (vn_unary_op_t) pool_alloc (current_info->unary_op_pool); vuo1->opcode = TREE_CODE (op); vuo1->type = TREE_TYPE (op); vuo1->op0 = TREE_OPERAND (op, 0); vuo1->result = result; if (TREE_CODE (vuo1->op0) == SSA_NAME) vuo1->op0 = SSA_VAL (vuo1->op0); vuo1->hashcode = vn_unary_op_compute_hash (vuo1); slot = htab_find_slot_with_hash (current_info->unary, vuo1, vuo1->hashcode, INSERT); gcc_assert (!*slot); *slot = vuo1; } /* Compute and return the hash value for binary operation VBO1. */ static inline hashval_t vn_binary_op_compute_hash (const vn_binary_op_t vbo1) { return iterative_hash_expr (vbo1->op0, vbo1->opcode) + iterative_hash_expr (vbo1->op1, vbo1->opcode); } /* Return the computed hashcode for binary operation P1. */ static hashval_t vn_binary_op_hash (const void *p1) { const_vn_binary_op_t const vbo1 = (const_vn_binary_op_t) p1; return vbo1->hashcode; } /* Compare binary operations P1 and P2 and return true if they are equivalent. */ static int vn_binary_op_eq (const void *p1, const void *p2) { const_vn_binary_op_t const vbo1 = (const_vn_binary_op_t) p1; const_vn_binary_op_t const vbo2 = (const_vn_binary_op_t) p2; return vbo1->opcode == vbo2->opcode && vbo1->type == vbo2->type && expressions_equal_p (vbo1->op0, vbo2->op0) && expressions_equal_p (vbo1->op1, vbo2->op1); } /* Lookup OP in the current hash table, and return the resulting value number if it exists in the hash table. Return NULL_TREE if it does not exist in the hash table. */ tree vn_binary_op_lookup (tree op) { void **slot; struct vn_binary_op_s vbo1; vbo1.opcode = TREE_CODE (op); vbo1.type = TREE_TYPE (op); vbo1.op0 = TREE_OPERAND (op, 0); vbo1.op1 = TREE_OPERAND (op, 1); if (TREE_CODE (vbo1.op0) == SSA_NAME) vbo1.op0 = SSA_VAL (vbo1.op0); if (TREE_CODE (vbo1.op1) == SSA_NAME) vbo1.op1 = SSA_VAL (vbo1.op1); if (tree_swap_operands_p (vbo1.op0, vbo1.op1, false) && commutative_tree_code (vbo1.opcode)) { tree temp = vbo1.op0; vbo1.op0 = vbo1.op1; vbo1.op1 = temp; } vbo1.hashcode = vn_binary_op_compute_hash (&vbo1); slot = htab_find_slot_with_hash (current_info->binary, &vbo1, vbo1.hashcode, NO_INSERT); if (!slot && current_info == optimistic_info) slot = htab_find_slot_with_hash (valid_info->binary, &vbo1, vbo1.hashcode, NO_INSERT); if (!slot) return NULL_TREE; return ((vn_binary_op_t)*slot)->result; } /* Insert OP into the current hash table with a value number of RESULT. */ void vn_binary_op_insert (tree op, tree result) { void **slot; vn_binary_op_t vbo1; vbo1 = (vn_binary_op_t) pool_alloc (current_info->binary_op_pool); vbo1->opcode = TREE_CODE (op); vbo1->type = TREE_TYPE (op); vbo1->op0 = TREE_OPERAND (op, 0); vbo1->op1 = TREE_OPERAND (op, 1); vbo1->result = result; if (TREE_CODE (vbo1->op0) == SSA_NAME) vbo1->op0 = SSA_VAL (vbo1->op0); if (TREE_CODE (vbo1->op1) == SSA_NAME) vbo1->op1 = SSA_VAL (vbo1->op1); if (tree_swap_operands_p (vbo1->op0, vbo1->op1, false) && commutative_tree_code (vbo1->opcode)) { tree temp = vbo1->op0; vbo1->op0 = vbo1->op1; vbo1->op1 = temp; } vbo1->hashcode = vn_binary_op_compute_hash (vbo1); slot = htab_find_slot_with_hash (current_info->binary, vbo1, vbo1->hashcode, INSERT); gcc_assert (!*slot); *slot = vbo1; } /* Compute a hashcode for PHI operation VP1 and return it. */ static inline hashval_t vn_phi_compute_hash (vn_phi_t vp1) { hashval_t result = 0; int i; tree phi1op; result = vp1->block->index; for (i = 0; VEC_iterate (tree, vp1->phiargs, i, phi1op); i++) { if (phi1op == VN_TOP) continue; result += iterative_hash_expr (phi1op, result); } return result; } /* Return the computed hashcode for phi operation P1. */ static hashval_t vn_phi_hash (const void *p1) { const_vn_phi_t const vp1 = (const_vn_phi_t) p1; return vp1->hashcode; } /* Compare two phi entries for equality, ignoring VN_TOP arguments. */ static int vn_phi_eq (const void *p1, const void *p2) { const_vn_phi_t const vp1 = (const_vn_phi_t) p1; const_vn_phi_t const vp2 = (const_vn_phi_t) p2; if (vp1->block == vp2->block) { int i; tree phi1op; /* Any phi in the same block will have it's arguments in the same edge order, because of how we store phi nodes. */ for (i = 0; VEC_iterate (tree, vp1->phiargs, i, phi1op); i++) { tree phi2op = VEC_index (tree, vp2->phiargs, i); if (phi1op == VN_TOP || phi2op == VN_TOP) continue; if (!expressions_equal_p (phi1op, phi2op)) return false; } return true; } return false; } static VEC(tree, heap) *shared_lookup_phiargs; /* Lookup PHI in the current hash table, and return the resulting value number if it exists in the hash table. Return NULL_TREE if it does not exist in the hash table. */ static tree vn_phi_lookup (tree phi) { void **slot; struct vn_phi_s vp1; int i; VEC_truncate (tree, shared_lookup_phiargs, 0); /* Canonicalize the SSA_NAME's to their value number. */ for (i = 0; i < PHI_NUM_ARGS (phi); i++) { tree def = PHI_ARG_DEF (phi, i); def = TREE_CODE (def) == SSA_NAME ? SSA_VAL (def) : def; VEC_safe_push (tree, heap, shared_lookup_phiargs, def); } vp1.phiargs = shared_lookup_phiargs; vp1.block = bb_for_stmt (phi); vp1.hashcode = vn_phi_compute_hash (&vp1); slot = htab_find_slot_with_hash (current_info->phis, &vp1, vp1.hashcode, NO_INSERT); if (!slot && current_info == optimistic_info) slot = htab_find_slot_with_hash (valid_info->phis, &vp1, vp1.hashcode, NO_INSERT); if (!slot) return NULL_TREE; return ((vn_phi_t)*slot)->result; } /* Insert PHI into the current hash table with a value number of RESULT. */ static void vn_phi_insert (tree phi, tree result) { void **slot; vn_phi_t vp1 = (vn_phi_t) pool_alloc (current_info->phis_pool); int i; VEC (tree, heap) *args = NULL; /* Canonicalize the SSA_NAME's to their value number. */ for (i = 0; i < PHI_NUM_ARGS (phi); i++) { tree def = PHI_ARG_DEF (phi, i); def = TREE_CODE (def) == SSA_NAME ? SSA_VAL (def) : def; VEC_safe_push (tree, heap, args, def); } vp1->phiargs = args; vp1->block = bb_for_stmt (phi); vp1->result = result; vp1->hashcode = vn_phi_compute_hash (vp1); slot = htab_find_slot_with_hash (current_info->phis, vp1, vp1->hashcode, INSERT); /* Because we iterate over phi operations more than once, it's possible the slot might already exist here, hence no assert.*/ *slot = vp1; } /* Print set of components in strongly connected component SCC to OUT. */ static void print_scc (FILE *out, VEC (tree, heap) *scc) { tree var; unsigned int i; fprintf (out, "SCC consists of: "); for (i = 0; VEC_iterate (tree, scc, i, var); i++) { print_generic_expr (out, var, 0); fprintf (out, " "); } fprintf (out, "\n"); } /* Set the value number of FROM to TO, return true if it has changed as a result. */ static inline bool set_ssa_val_to (tree from, tree to) { tree currval; if (from != to && TREE_CODE (to) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (to)) to = from; /* The only thing we allow as value numbers are VN_TOP, ssa_names and invariants. So assert that here. */ gcc_assert (to != NULL_TREE && (to == VN_TOP || TREE_CODE (to) == SSA_NAME || is_gimple_min_invariant (to))); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Setting value number of "); print_generic_expr (dump_file, from, 0); fprintf (dump_file, " to "); print_generic_expr (dump_file, to, 0); fprintf (dump_file, "\n"); } currval = SSA_VAL (from); if (currval != to && !operand_equal_p (currval, to, OEP_PURE_SAME)) { SSA_VAL (from) = to; return true; } return false; } /* Set all definitions in STMT to value number to themselves. Return true if a value number changed. */ static bool defs_to_varying (tree stmt) { bool changed = false; ssa_op_iter iter; def_operand_p defp; FOR_EACH_SSA_DEF_OPERAND (defp, stmt, iter, SSA_OP_ALL_DEFS) { tree def = DEF_FROM_PTR (defp); VN_INFO (def)->use_processed = true; changed |= set_ssa_val_to (def, def); } return changed; } /* Visit a copy between LHS and RHS, return true if the value number changed. */ static bool visit_copy (tree lhs, tree rhs) { /* Follow chains of copies to their destination. */ while (SSA_VAL (rhs) != rhs && TREE_CODE (SSA_VAL (rhs)) == SSA_NAME) rhs = SSA_VAL (rhs); /* The copy may have a more interesting constant filled expression (we don't, since we know our RHS is just an SSA name). */ VN_INFO (lhs)->has_constants = VN_INFO (rhs)->has_constants; VN_INFO (lhs)->expr = VN_INFO (rhs)->expr; return set_ssa_val_to (lhs, rhs); } /* Visit a unary operator RHS, value number it, and return true if the value number of LHS has changed as a result. */ static bool visit_unary_op (tree lhs, tree op) { bool changed = false; tree result = vn_unary_op_lookup (op); if (result) { changed = set_ssa_val_to (lhs, result); } else { changed = set_ssa_val_to (lhs, lhs); vn_unary_op_insert (op, lhs); } return changed; } /* Visit a binary operator RHS, value number it, and return true if the value number of LHS has changed as a result. */ static bool visit_binary_op (tree lhs, tree op) { bool changed = false; tree result = vn_binary_op_lookup (op); if (result) { changed = set_ssa_val_to (lhs, result); } else { changed = set_ssa_val_to (lhs, lhs); vn_binary_op_insert (op, lhs); } return changed; } /* Visit a load from a reference operator RHS, part of STMT, value number it, and return true if the value number of the LHS has changed as a result. */ static bool visit_reference_op_load (tree lhs, tree op, tree stmt) { bool changed = false; tree result = vn_reference_lookup (op, shared_vuses_from_stmt (stmt)); if (result) { changed = set_ssa_val_to (lhs, result); } else { changed = set_ssa_val_to (lhs, lhs); vn_reference_insert (op, lhs, copy_vuses_from_stmt (stmt)); } return changed; } /* Visit a store to a reference operator LHS, part of STMT, value number it, and return true if the value number of the LHS has changed as a result. */ static bool visit_reference_op_store (tree lhs, tree op, tree stmt) { bool changed = false; tree result; bool resultsame = false; /* First we want to lookup using the *vuses* from the store and see if there the last store to this location with the same address had the same value. The vuses represent the memory state before the store. If the memory state, address, and value of the store is the same as the last store to this location, then this store will produce the same memory state as that store. In this case the vdef versions for this store are value numbered to those vuse versions, since they represent the same memory state after this store. Otherwise, the vdefs for the store are used when inserting into the table, since the store generates a new memory state. */ result = vn_reference_lookup (lhs, shared_vuses_from_stmt (stmt)); if (result) { if (TREE_CODE (result) == SSA_NAME) result = SSA_VAL (result); resultsame = expressions_equal_p (result, op); } if (!result || !resultsame) { VEC(tree, gc) *vdefs = copy_vdefs_from_stmt (stmt); int i; tree vdef; if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "No store match\n"); fprintf (dump_file, "Value numbering store "); print_generic_expr (dump_file, lhs, 0); fprintf (dump_file, " to "); print_generic_expr (dump_file, op, 0); fprintf (dump_file, "\n"); } /* Have to set value numbers before insert, since insert is going to valueize the references in-place. */ for (i = 0; VEC_iterate (tree, vdefs, i, vdef); i++) { VN_INFO (vdef)->use_processed = true; changed |= set_ssa_val_to (vdef, vdef); } vn_reference_insert (lhs, op, vdefs); } else { /* We had a match, so value number the vdefs to have the value number of the vuses they came from. */ ssa_op_iter op_iter; def_operand_p var; vuse_vec_p vv; if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "Store matched earlier value," "value numbering store vdefs to matching vuses.\n"); FOR_EACH_SSA_VDEF_OPERAND (var, vv, stmt, op_iter) { tree def = DEF_FROM_PTR (var); tree use; /* Uh, if the vuse is a multiuse, we can't really do much here, sadly, since we don't know which value number of which vuse to use. */ if (VUSE_VECT_NUM_ELEM (*vv) != 1) use = def; else use = VUSE_ELEMENT_VAR (*vv, 0); VN_INFO (def)->use_processed = true; changed |= set_ssa_val_to (def, SSA_VAL (use)); } } return changed; } /* Visit and value number PHI, return true if the value number changed. */ static bool visit_phi (tree phi) { bool changed = false; tree result; tree sameval = VN_TOP; bool allsame = true; int i; /* TODO: We could check for this in init_sccvn, and replace this with a gcc_assert. */ if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi))) return set_ssa_val_to (PHI_RESULT (phi), PHI_RESULT (phi)); /* See if all non-TOP arguments have the same value. TOP is equivalent to everything, so we can ignore it. */ for (i = 0; i < PHI_NUM_ARGS (phi); i++) { tree def = PHI_ARG_DEF (phi, i); if (TREE_CODE (def) == SSA_NAME) def = SSA_VAL (def); if (def == VN_TOP) continue; if (sameval == VN_TOP) { sameval = def; } else { if (!expressions_equal_p (def, sameval)) { allsame = false; break; } } } /* If all value numbered to the same value, the phi node has that value. */ if (allsame) { if (is_gimple_min_invariant (sameval)) { VN_INFO (PHI_RESULT (phi))->has_constants = true; VN_INFO (PHI_RESULT (phi))->expr = sameval; } else { VN_INFO (PHI_RESULT (phi))->has_constants = false; VN_INFO (PHI_RESULT (phi))->expr = sameval; } if (TREE_CODE (sameval) == SSA_NAME) return visit_copy (PHI_RESULT (phi), sameval); return set_ssa_val_to (PHI_RESULT (phi), sameval); } /* Otherwise, see if it is equivalent to a phi node in this block. */ result = vn_phi_lookup (phi); if (result) { if (TREE_CODE (result) == SSA_NAME) changed = visit_copy (PHI_RESULT (phi), result); else changed = set_ssa_val_to (PHI_RESULT (phi), result); } else { vn_phi_insert (phi, PHI_RESULT (phi)); VN_INFO (PHI_RESULT (phi))->has_constants = false; VN_INFO (PHI_RESULT (phi))->expr = PHI_RESULT (phi); changed = set_ssa_val_to (PHI_RESULT (phi), PHI_RESULT (phi)); } return changed; } /* Return true if EXPR contains constants. */ static bool expr_has_constants (tree expr) { switch (TREE_CODE_CLASS (TREE_CODE (expr))) { case tcc_unary: return is_gimple_min_invariant (TREE_OPERAND (expr, 0)); case tcc_binary: return is_gimple_min_invariant (TREE_OPERAND (expr, 0)) || is_gimple_min_invariant (TREE_OPERAND (expr, 1)); /* Constants inside reference ops are rarely interesting, but it can take a lot of looking to find them. */ case tcc_reference: case tcc_declaration: return false; default: return is_gimple_min_invariant (expr); } return false; } /* Replace SSA_NAMES in expr with their value numbers, and return the result. This is performed in place. */ static tree valueize_expr (tree expr) { switch (TREE_CODE_CLASS (TREE_CODE (expr))) { case tcc_unary: if (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME && SSA_VAL (TREE_OPERAND (expr, 0)) != VN_TOP) TREE_OPERAND (expr, 0) = SSA_VAL (TREE_OPERAND (expr, 0)); break; case tcc_binary: if (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME && SSA_VAL (TREE_OPERAND (expr, 0)) != VN_TOP) TREE_OPERAND (expr, 0) = SSA_VAL (TREE_OPERAND (expr, 0)); if (TREE_CODE (TREE_OPERAND (expr, 1)) == SSA_NAME && SSA_VAL (TREE_OPERAND (expr, 1)) != VN_TOP) TREE_OPERAND (expr, 1) = SSA_VAL (TREE_OPERAND (expr, 1)); break; default: break; } return expr; } /* Simplify the binary expression RHS, and return the result if simplified. */ static tree simplify_binary_expression (tree stmt, tree rhs) { tree result = NULL_TREE; tree op0 = TREE_OPERAND (rhs, 0); tree op1 = TREE_OPERAND (rhs, 1); /* This will not catch every single case we could combine, but will catch those with constants. The goal here is to simultaneously combine constants between expressions, but avoid infinite expansion of expressions during simplification. */ if (TREE_CODE (op0) == SSA_NAME) { if (VN_INFO (op0)->has_constants) op0 = valueize_expr (VN_INFO (op0)->expr); else if (SSA_VAL (op0) != VN_TOP && SSA_VAL (op0) != op0) op0 = SSA_VAL (op0); } if (TREE_CODE (op1) == SSA_NAME) { if (VN_INFO (op1)->has_constants) op1 = valueize_expr (VN_INFO (op1)->expr); else if (SSA_VAL (op1) != VN_TOP && SSA_VAL (op1) != op1) op1 = SSA_VAL (op1); } /* Avoid folding if nothing changed. */ if (op0 == TREE_OPERAND (rhs, 0) && op1 == TREE_OPERAND (rhs, 1)) return NULL_TREE; fold_defer_overflow_warnings (); result = fold_binary (TREE_CODE (rhs), TREE_TYPE (rhs), op0, op1); fold_undefer_overflow_warnings (result && valid_gimple_expression_p (result), stmt, 0); /* Make sure result is not a complex expression consisting of operators of operators (IE (a + b) + (a + c)) Otherwise, we will end up with unbounded expressions if fold does anything at all. */ if (result && valid_gimple_expression_p (result)) return result; return NULL_TREE; } /* Simplify the unary expression RHS, and return the result if simplified. */ static tree simplify_unary_expression (tree rhs) { tree result = NULL_TREE; tree op0 = TREE_OPERAND (rhs, 0); if (TREE_CODE (op0) != SSA_NAME) return NULL_TREE; if (VN_INFO (op0)->has_constants) op0 = valueize_expr (VN_INFO (op0)->expr); else if (TREE_CODE (rhs) == NOP_EXPR || TREE_CODE (rhs) == CONVERT_EXPR || TREE_CODE (rhs) == REALPART_EXPR || TREE_CODE (rhs) == IMAGPART_EXPR) { /* We want to do tree-combining on conversion-like expressions. Make sure we feed only SSA_NAMEs or constants to fold though. */ tree tem = valueize_expr (VN_INFO (op0)->expr); if (UNARY_CLASS_P (tem) || BINARY_CLASS_P (tem) || TREE_CODE (tem) == SSA_NAME || is_gimple_min_invariant (tem)) op0 = tem; } /* Avoid folding if nothing changed, but remember the expression. */ if (op0 == TREE_OPERAND (rhs, 0)) return rhs; result = fold_unary (TREE_CODE (rhs), TREE_TYPE (rhs), op0); if (result) { STRIP_USELESS_TYPE_CONVERSION (result); if (valid_gimple_expression_p (result)) return result; } return rhs; } /* Try to simplify RHS using equivalences and constant folding. */ static tree try_to_simplify (tree stmt, tree rhs) { if (TREE_CODE (rhs) == SSA_NAME) { if (is_gimple_min_invariant (SSA_VAL (rhs))) return SSA_VAL (rhs); else if (VN_INFO (rhs)->has_constants) return VN_INFO (rhs)->expr; } else { switch (TREE_CODE_CLASS (TREE_CODE (rhs))) { /* For references, see if we find a result for the lookup, and use it if we do. */ case tcc_declaration: /* Pull out any truly constant values. */ if (TREE_READONLY (rhs) && TREE_STATIC (rhs) && DECL_INITIAL (rhs) && valid_gimple_expression_p (DECL_INITIAL (rhs))) return DECL_INITIAL (rhs); /* Fallthrough. */ case tcc_reference: { tree result = vn_reference_lookup (rhs, shared_vuses_from_stmt (stmt)); if (result) return result; } /* Fallthrough for some codes. */ if (!(TREE_CODE (rhs) == REALPART_EXPR || TREE_CODE (rhs) == IMAGPART_EXPR)) break; /* We could do a little more with unary ops, if they expand into binary ops, but it's debatable whether it is worth it. */ case tcc_unary: return simplify_unary_expression (rhs); break; case tcc_comparison: case tcc_binary: return simplify_binary_expression (stmt, rhs); break; default: break; } } return rhs; } /* Visit and value number USE, return true if the value number changed. */ static bool visit_use (tree use) { bool changed = false; tree stmt = SSA_NAME_DEF_STMT (use); stmt_ann_t ann; VN_INFO (use)->use_processed = true; gcc_assert (!SSA_NAME_IN_FREE_LIST (use)); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Value numbering "); print_generic_expr (dump_file, use, 0); fprintf (dump_file, " stmt = "); print_generic_stmt (dump_file, stmt, 0); } /* RETURN_EXPR may have an embedded MODIFY_STMT. */ if (TREE_CODE (stmt) == RETURN_EXPR && TREE_CODE (TREE_OPERAND (stmt, 0)) == GIMPLE_MODIFY_STMT) stmt = TREE_OPERAND (stmt, 0); ann = stmt_ann (stmt); /* Handle uninitialized uses. */ if (IS_EMPTY_STMT (stmt)) { changed = set_ssa_val_to (use, use); } else { if (TREE_CODE (stmt) == PHI_NODE) { changed = visit_phi (stmt); } else if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT || (ann && ann->has_volatile_ops) || tree_could_throw_p (stmt)) { changed = defs_to_varying (stmt); } else { tree lhs = GIMPLE_STMT_OPERAND (stmt, 0); tree rhs = GIMPLE_STMT_OPERAND (stmt, 1); tree simplified; STRIP_USELESS_TYPE_CONVERSION (rhs); /* Shortcut for copies. Simplifying copies is pointless, since we copy the expression and value they represent. */ if (TREE_CODE (rhs) == SSA_NAME && TREE_CODE (lhs) == SSA_NAME) { changed = visit_copy (lhs, rhs); goto done; } simplified = try_to_simplify (stmt, rhs); if (simplified && simplified != rhs) { if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "RHS "); print_generic_expr (dump_file, rhs, 0); fprintf (dump_file, " simplified to "); print_generic_expr (dump_file, simplified, 0); if (TREE_CODE (lhs) == SSA_NAME) fprintf (dump_file, " has constants %d\n", VN_INFO (lhs)->has_constants); else fprintf (dump_file, "\n"); } } /* Setting value numbers to constants will occasionally screw up phi congruence because constants are not uniquely associated with a single ssa name that can be looked up. */ if (simplified && is_gimple_min_invariant (simplified) && TREE_CODE (lhs) == SSA_NAME && simplified != rhs) { VN_INFO (lhs)->expr = simplified; VN_INFO (lhs)->has_constants = true; changed = set_ssa_val_to (lhs, simplified); goto done; } else if (simplified && TREE_CODE (simplified) == SSA_NAME && TREE_CODE (lhs) == SSA_NAME) { changed = visit_copy (lhs, simplified); goto done; } else if (simplified) { if (TREE_CODE (lhs) == SSA_NAME) { VN_INFO (lhs)->has_constants = expr_has_constants (simplified); /* We have to unshare the expression or else valuizing may change the IL stream. */ VN_INFO (lhs)->expr = unshare_expr (simplified); } rhs = simplified; } else if (expr_has_constants (rhs) && TREE_CODE (lhs) == SSA_NAME) { VN_INFO (lhs)->has_constants = true; VN_INFO (lhs)->expr = unshare_expr (rhs); } else if (TREE_CODE (lhs) == SSA_NAME) { /* We reset expr and constantness here because we may have been value numbering optimistically, and iterating. They may become non-constant in this case, even if they were optimistically constant. */ VN_INFO (lhs)->has_constants = false; VN_INFO (lhs)->expr = lhs; } if (TREE_CODE (lhs) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs)) changed = defs_to_varying (stmt); else if (REFERENCE_CLASS_P (lhs) || DECL_P (lhs)) { changed = visit_reference_op_store (lhs, rhs, stmt); } else if (TREE_CODE (lhs) == SSA_NAME) { if (is_gimple_min_invariant (rhs)) { VN_INFO (lhs)->has_constants = true; VN_INFO (lhs)->expr = rhs; changed = set_ssa_val_to (lhs, rhs); } else { switch (TREE_CODE_CLASS (TREE_CODE (rhs))) { case tcc_unary: changed = visit_unary_op (lhs, rhs); break; case tcc_binary: changed = visit_binary_op (lhs, rhs); break; /* If tcc_vl_expr ever encompasses more than CALL_EXPR, this will need to be changed. */ case tcc_vl_exp: if (call_expr_flags (rhs) & (ECF_PURE | ECF_CONST)) changed = visit_reference_op_load (lhs, rhs, stmt); else changed = defs_to_varying (stmt); break; case tcc_declaration: case tcc_reference: changed = visit_reference_op_load (lhs, rhs, stmt); break; case tcc_expression: if (TREE_CODE (rhs) == ADDR_EXPR) { changed = visit_unary_op (lhs, rhs); goto done; } /* Fallthrough. */ default: changed = defs_to_varying (stmt); break; } } } else changed = defs_to_varying (stmt); } } done: return changed; } /* Compare two operands by reverse postorder index */ static int compare_ops (const void *pa, const void *pb) { const tree opa = *((const tree *)pa); const tree opb = *((const tree *)pb); tree opstmta = SSA_NAME_DEF_STMT (opa); tree opstmtb = SSA_NAME_DEF_STMT (opb); basic_block bba; basic_block bbb; if (IS_EMPTY_STMT (opstmta) && IS_EMPTY_STMT (opstmtb)) return 0; else if (IS_EMPTY_STMT (opstmta)) return -1; else if (IS_EMPTY_STMT (opstmtb)) return 1; bba = bb_for_stmt (opstmta); bbb = bb_for_stmt (opstmtb); if (!bba && !bbb) return 0; else if (!bba) return -1; else if (!bbb) return 1; if (bba == bbb) { if (TREE_CODE (opstmta) == PHI_NODE && TREE_CODE (opstmtb) == PHI_NODE) return 0; else if (TREE_CODE (opstmta) == PHI_NODE) return -1; else if (TREE_CODE (opstmtb) == PHI_NODE) return 1; return stmt_ann (opstmta)->uid - stmt_ann (opstmtb)->uid; } return rpo_numbers[bba->index] - rpo_numbers[bbb->index]; } /* Sort an array containing members of a strongly connected component SCC so that the members are ordered by RPO number. This means that when the sort is complete, iterating through the array will give you the members in RPO order. */ static void sort_scc (VEC (tree, heap) *scc) { qsort (VEC_address (tree, scc), VEC_length (tree, scc), sizeof (tree), compare_ops); } /* Process a strongly connected component in the SSA graph. */ static void process_scc (VEC (tree, heap) *scc) { /* If the SCC has a single member, just visit it. */ if (VEC_length (tree, scc) == 1) { tree use = VEC_index (tree, scc, 0); if (!VN_INFO (use)->use_processed) visit_use (use); } else { tree var; unsigned int i; unsigned int iterations = 0; bool changed = true; /* Iterate over the SCC with the optimistic table until it stops changing. */ current_info = optimistic_info; while (changed) { changed = false; iterations++; htab_empty (optimistic_info->unary); htab_empty (optimistic_info->binary); htab_empty (optimistic_info->phis); htab_empty (optimistic_info->references); empty_alloc_pool (optimistic_info->unary_op_pool); empty_alloc_pool (optimistic_info->binary_op_pool); empty_alloc_pool (optimistic_info->phis_pool); empty_alloc_pool (optimistic_info->references_pool); for (i = 0; VEC_iterate (tree, scc, i, var); i++) changed |= visit_use (var); } if (dump_file && (dump_flags & TDF_STATS)) fprintf (dump_file, "Processing SCC required %d iterations\n", iterations); /* Finally, visit the SCC once using the valid table. */ current_info = valid_info; for (i = 0; VEC_iterate (tree, scc, i, var); i++) visit_use (var); } } DEF_VEC_O(ssa_op_iter); DEF_VEC_ALLOC_O(ssa_op_iter,heap); /* Pop the components of the found SCC for NAME off the SCC stack and process them. Returns true if all went well, false if we run into resource limits. */ static bool extract_and_process_scc_for_name (tree name) { VEC (tree, heap) *scc = NULL; tree x; /* Found an SCC, pop the components off the SCC stack and process them. */ do { x = VEC_pop (tree, sccstack); VN_INFO (x)->on_sccstack = false; VEC_safe_push (tree, heap, scc, x); } while (x != name); /* Bail out of SCCVN in case a SCC turns out to be incredibly large. */ if (VEC_length (tree, scc) > (unsigned)PARAM_VALUE (PARAM_SCCVN_MAX_SCC_SIZE)) { if (dump_file) fprintf (dump_file, "WARNING: Giving up with SCCVN due to " "SCC size %u exceeding %u\n", VEC_length (tree, scc), (unsigned)PARAM_VALUE (PARAM_SCCVN_MAX_SCC_SIZE)); return false; } if (VEC_length (tree, scc) > 1) sort_scc (scc); if (dump_file && (dump_flags & TDF_DETAILS)) print_scc (dump_file, scc); process_scc (scc); VEC_free (tree, heap, scc); return true; } /* Depth first search on NAME to discover and process SCC's in the SSA graph. Execution of this algorithm relies on the fact that the SCC's are popped off the stack in topological order. Returns true if successful, false if we stopped processing SCC's due to ressource constraints. */ static bool DFS (tree name) { VEC(ssa_op_iter, heap) *itervec = NULL; VEC(tree, heap) *namevec = NULL; use_operand_p usep = NULL; tree defstmt, use; ssa_op_iter iter; start_over: /* SCC info */ VN_INFO (name)->dfsnum = next_dfs_num++; VN_INFO (name)->visited = true; VN_INFO (name)->low = VN_INFO (name)->dfsnum; VEC_safe_push (tree, heap, sccstack, name); VN_INFO (name)->on_sccstack = true; defstmt = SSA_NAME_DEF_STMT (name); /* Recursively DFS on our operands, looking for SCC's. */ if (!IS_EMPTY_STMT (defstmt)) { /* Push a new iterator. */ if (TREE_CODE (defstmt) == PHI_NODE) usep = op_iter_init_phiuse (&iter, defstmt, SSA_OP_ALL_USES); else usep = op_iter_init_use (&iter, defstmt, SSA_OP_ALL_USES); } else iter.done = true; while (1) { /* If we are done processing uses of a name, go up the stack of iterators and process SCCs as we found them. */ if (op_iter_done (&iter)) { /* See if we found an SCC. */ if (VN_INFO (name)->low == VN_INFO (name)->dfsnum) if (!extract_and_process_scc_for_name (name)) { VEC_free (tree, heap, namevec); VEC_free (ssa_op_iter, heap, itervec); return false; } /* Check if we are done. */ if (VEC_empty (tree, namevec)) { VEC_free (tree, heap, namevec); VEC_free (ssa_op_iter, heap, itervec); return true; } /* Restore the last use walker and continue walking there. */ use = name; name = VEC_pop (tree, namevec); memcpy (&iter, VEC_last (ssa_op_iter, itervec), sizeof (ssa_op_iter)); VEC_pop (ssa_op_iter, itervec); goto continue_walking; } use = USE_FROM_PTR (usep); /* Since we handle phi nodes, we will sometimes get invariants in the use expression. */ if (TREE_CODE (use) == SSA_NAME) { if (! (VN_INFO (use)->visited)) { /* Recurse by pushing the current use walking state on the stack and starting over. */ VEC_safe_push(ssa_op_iter, heap, itervec, &iter); VEC_safe_push(tree, heap, namevec, name); name = use; goto start_over; continue_walking: VN_INFO (name)->low = MIN (VN_INFO (name)->low, VN_INFO (use)->low); } if (VN_INFO (use)->dfsnum < VN_INFO (name)->dfsnum && VN_INFO (use)->on_sccstack) { VN_INFO (name)->low = MIN (VN_INFO (use)->dfsnum, VN_INFO (name)->low); } } usep = op_iter_next_use (&iter); } } /* Allocate a value number table. */ static void allocate_vn_table (vn_tables_t table) { table->phis = htab_create (23, vn_phi_hash, vn_phi_eq, free_phi); table->unary = htab_create (23, vn_unary_op_hash, vn_unary_op_eq, NULL); table->binary = htab_create (23, vn_binary_op_hash, vn_binary_op_eq, NULL); table->references = htab_create (23, vn_reference_hash, vn_reference_eq, free_reference); table->unary_op_pool = create_alloc_pool ("VN unary operations", sizeof (struct vn_unary_op_s), 30); table->binary_op_pool = create_alloc_pool ("VN binary operations", sizeof (struct vn_binary_op_s), 30); table->phis_pool = create_alloc_pool ("VN phis", sizeof (struct vn_phi_s), 30); table->references_pool = create_alloc_pool ("VN references", sizeof (struct vn_reference_s), 30); } /* Free a value number table. */ static void free_vn_table (vn_tables_t table) { htab_delete (table->phis); htab_delete (table->unary); htab_delete (table->binary); htab_delete (table->references); free_alloc_pool (table->unary_op_pool); free_alloc_pool (table->binary_op_pool); free_alloc_pool (table->phis_pool); free_alloc_pool (table->references_pool); } static void init_scc_vn (void) { size_t i; int j; int *rpo_numbers_temp; basic_block bb; size_t id = 0; calculate_dominance_info (CDI_DOMINATORS); sccstack = NULL; next_dfs_num = 1; vn_ssa_aux_table = VEC_alloc (vn_ssa_aux_t, heap, num_ssa_names + 1); /* VEC_alloc doesn't actually grow it to the right size, it just preallocates the space to do so. */ VEC_safe_grow (vn_ssa_aux_t, heap, vn_ssa_aux_table, num_ssa_names + 1); shared_lookup_phiargs = NULL; shared_lookup_vops = NULL; shared_lookup_references = NULL; rpo_numbers = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS); rpo_numbers_temp = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS); pre_and_rev_post_order_compute (NULL, rpo_numbers_temp, false); /* RPO numbers is an array of rpo ordering, rpo[i] = bb means that the i'th block in RPO order is bb. We want to map bb's to RPO numbers, so we need to rearrange this array. */ for (j = 0; j < n_basic_blocks - NUM_FIXED_BLOCKS; j++) rpo_numbers[rpo_numbers_temp[j]] = j; free (rpo_numbers_temp); VN_TOP = create_tmp_var_raw (void_type_node, "vn_top"); /* Create the VN_INFO structures, and initialize value numbers to TOP. */ for (i = 0; i < num_ssa_names; i++) { tree name = ssa_name (i); if (name) { VN_INFO_GET (name)->valnum = VN_TOP; VN_INFO (name)->expr = name; } } FOR_ALL_BB (bb) { block_stmt_iterator bsi; for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) { tree stmt = bsi_stmt (bsi); stmt_ann (stmt)->uid = id++; } } /* Create the valid and optimistic value numbering tables. */ valid_info = XCNEW (struct vn_tables_s); allocate_vn_table (valid_info); optimistic_info = XCNEW (struct vn_tables_s); allocate_vn_table (optimistic_info); pre_info = NULL; } void switch_to_PRE_table (void) { pre_info = XCNEW (struct vn_tables_s); allocate_vn_table (pre_info); current_info = pre_info; } void free_scc_vn (void) { size_t i; VEC_free (tree, heap, shared_lookup_phiargs); VEC_free (tree, gc, shared_lookup_vops); VEC_free (vn_reference_op_s, heap, shared_lookup_references); XDELETEVEC (rpo_numbers); for (i = 0; i < num_ssa_names; i++) { tree name = ssa_name (i); if (name) { XDELETE (VN_INFO (name)); if (SSA_NAME_VALUE (name) && TREE_CODE (SSA_NAME_VALUE (name)) == VALUE_HANDLE) SSA_NAME_VALUE (name) = NULL; } } VEC_free (vn_ssa_aux_t, heap, vn_ssa_aux_table); VEC_free (tree, heap, sccstack); free_vn_table (valid_info); XDELETE (valid_info); free_vn_table (optimistic_info); XDELETE (optimistic_info); if (pre_info) { free_vn_table (pre_info); XDELETE (pre_info); } } /* Do SCCVN. Returns true if it finished, false if we bailed out due to ressource constraints. */ bool run_scc_vn (void) { size_t i; tree param; init_scc_vn (); current_info = valid_info; for (param = DECL_ARGUMENTS (current_function_decl); param; param = TREE_CHAIN (param)) { if (gimple_default_def (cfun, param) != NULL) { tree def = gimple_default_def (cfun, param); SSA_VAL (def) = def; } } for (i = num_ssa_names - 1; i > 0; i--) { tree name = ssa_name (i); if (name && VN_INFO (name)->visited == false && !has_zero_uses (name)) if (!DFS (name)) { free_scc_vn (); return false; } } if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Value numbers:\n"); for (i = 0; i < num_ssa_names; i++) { tree name = ssa_name (i); if (name && VN_INFO (name)->visited && (SSA_VAL (name) != name || is_gimple_min_invariant (VN_INFO (name)->expr))) { print_generic_expr (dump_file, name, 0); fprintf (dump_file, " = "); if (is_gimple_min_invariant (VN_INFO (name)->expr)) print_generic_expr (dump_file, VN_INFO (name)->expr, 0); else print_generic_expr (dump_file, SSA_VAL (name), 0); fprintf (dump_file, "\n"); } } } return true; }