diff options
Diffstat (limited to 'gcc-4.9/gcc/ifcvt.c')
| -rw-r--r-- | gcc-4.9/gcc/ifcvt.c | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/gcc-4.9/gcc/ifcvt.c b/gcc-4.9/gcc/ifcvt.c index 0d1adce95..49ff85c7f 100644 --- a/gcc-4.9/gcc/ifcvt.c +++ b/gcc-4.9/gcc/ifcvt.c @@ -306,6 +306,28 @@ block_fallthru (basic_block bb) return (e) ? e->dest : NULL_BLOCK; } + +/* Return true if RTXs A and B can be safely interchanged. */ + +static bool +rtx_interchangeable_p (const_rtx a, const_rtx b) +{ + if (!rtx_equal_p (a, b)) + return false; + + if (GET_CODE (a) != MEM) + return true; + + /* A dead type-unsafe memory reference is legal, but a live type-unsafe memory + reference is not. Interchanging a dead type-unsafe memory reference with + a live type-safe one creates a live type-unsafe memory reference, in other + words, it makes the program illegal. + We check here conservatively whether the two memory references have equal + memory attributes. */ + + return mem_attrs_eq_p (get_mem_attrs (a), get_mem_attrs (b)); +} + /* Go through a bunch of insns, converting them to conditional execution format if possible. Return TRUE if all of the non-note @@ -1034,6 +1056,9 @@ noce_try_move (struct noce_if_info *if_info) || (rtx_equal_p (if_info->a, XEXP (cond, 1)) && rtx_equal_p (if_info->b, XEXP (cond, 0)))) { + if (!rtx_interchangeable_p (if_info->a, if_info->b)) + return FALSE; + y = (code == EQ) ? if_info->a : if_info->b; /* Avoid generating the move if the source is the destination. */ @@ -2504,7 +2529,7 @@ noce_process_if_block (struct noce_if_info *if_info) if (! insn_b || insn_b != last_active_insn (else_bb, FALSE) || (set_b = single_set (insn_b)) == NULL_RTX - || ! rtx_equal_p (x, SET_DEST (set_b))) + || ! rtx_interchangeable_p (x, SET_DEST (set_b))) return FALSE; } else @@ -2517,7 +2542,7 @@ noce_process_if_block (struct noce_if_info *if_info) || BLOCK_FOR_INSN (insn_b) != BLOCK_FOR_INSN (if_info->cond_earliest) || !NONJUMP_INSN_P (insn_b) || (set_b = single_set (insn_b)) == NULL_RTX - || ! rtx_equal_p (x, SET_DEST (set_b)) + || ! rtx_interchangeable_p (x, SET_DEST (set_b)) || ! noce_operand_ok (SET_SRC (set_b)) || reg_overlap_mentioned_p (x, SET_SRC (set_b)) || modified_between_p (SET_SRC (set_b), insn_b, jump) @@ -2583,7 +2608,7 @@ noce_process_if_block (struct noce_if_info *if_info) /* Look and see if A and B are really the same. Avoid creating silly cmove constructs that no one will fix up later. */ - if (rtx_equal_p (a, b)) + if (rtx_interchangeable_p (a, b)) { /* If we have an INSN_B, we don't have to create any new rtl. Just move the instruction that we already have. If we don't have an |