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Diffstat (limited to 'compiler/dex/quick/arm64/utility_arm64.cc')
-rw-r--r--compiler/dex/quick/arm64/utility_arm64.cc206
1 files changed, 158 insertions, 48 deletions
diff --git a/compiler/dex/quick/arm64/utility_arm64.cc b/compiler/dex/quick/arm64/utility_arm64.cc
index cd1840ae0a..5326e74e16 100644
--- a/compiler/dex/quick/arm64/utility_arm64.cc
+++ b/compiler/dex/quick/arm64/utility_arm64.cc
@@ -269,8 +269,47 @@ int Arm64Mir2Lir::EncodeLogicalImmediate(bool is_wide, uint64_t value) {
return (n << 12 | imm_r << 6 | imm_s);
}
+// Maximum number of instructions to use for encoding the immediate.
+static const int max_num_ops_per_const_load = 2;
+
+/**
+ * @brief Return the number of fast halfwords in the given uint64_t integer.
+ * @details The input integer is split into 4 halfwords (bits 0-15, 16-31, 32-47, 48-63). The
+ * number of fast halfwords (halfwords that are either 0 or 0xffff) is returned. See below for
+ * a more accurate description.
+ * @param value The input 64-bit integer.
+ * @return Return @c retval such that (retval & 0x7) is the maximum between n and m, where n is
+ * the number of halfwords with all bits unset (0) and m is the number of halfwords with all bits
+ * set (0xffff). Additionally (retval & 0x8) is set when m > n.
+ */
+static int GetNumFastHalfWords(uint64_t value) {
+ unsigned int num_0000_halfwords = 0;
+ unsigned int num_ffff_halfwords = 0;
+ for (int shift = 0; shift < 64; shift += 16) {
+ uint16_t halfword = static_cast<uint16_t>(value >> shift);
+ if (halfword == 0)
+ num_0000_halfwords++;
+ else if (halfword == UINT16_C(0xffff))
+ num_ffff_halfwords++;
+ }
+ if (num_0000_halfwords >= num_ffff_halfwords) {
+ DCHECK_LE(num_0000_halfwords, 4U);
+ return num_0000_halfwords;
+ } else {
+ DCHECK_LE(num_ffff_halfwords, 4U);
+ return num_ffff_halfwords | 0x8;
+ }
+}
+
+// The InexpensiveConstantXXX variants below are used in the promotion algorithm to determine how a
+// constant is considered for promotion. If the constant is "inexpensive" then the promotion
+// algorithm will give it a low priority for promotion, even when it is referenced many times in
+// the code.
+
bool Arm64Mir2Lir::InexpensiveConstantInt(int32_t value) {
- return false; // (ModifiedImmediate(value) >= 0) || (ModifiedImmediate(~value) >= 0);
+ // A 32-bit int can always be loaded with 2 instructions (and without using the literal pool).
+ // We therefore return true and give it a low priority for promotion.
+ return true;
}
bool Arm64Mir2Lir::InexpensiveConstantFloat(int32_t value) {
@@ -278,13 +317,70 @@ bool Arm64Mir2Lir::InexpensiveConstantFloat(int32_t value) {
}
bool Arm64Mir2Lir::InexpensiveConstantLong(int64_t value) {
- return InexpensiveConstantInt(High32Bits(value)) && InexpensiveConstantInt(Low32Bits(value));
+ int num_slow_halfwords = 4 - (GetNumFastHalfWords(value) & 0x7);
+ if (num_slow_halfwords <= max_num_ops_per_const_load) {
+ return true;
+ }
+ return (EncodeLogicalImmediate(/*is_wide=*/true, value) >= 0);
}
bool Arm64Mir2Lir::InexpensiveConstantDouble(int64_t value) {
return EncodeImmDouble(value) >= 0;
}
+// The InexpensiveConstantXXX variants below are used to determine which A64 instructions to use
+// when one of the operands is an immediate (e.g. register version or immediate version of add).
+
+bool Arm64Mir2Lir::InexpensiveConstantInt(int32_t value, Instruction::Code opcode) {
+ switch (opcode) {
+ case Instruction::IF_EQ:
+ case Instruction::IF_NE:
+ case Instruction::IF_LT:
+ case Instruction::IF_GE:
+ case Instruction::IF_GT:
+ case Instruction::IF_LE:
+ case Instruction::ADD_INT:
+ case Instruction::ADD_INT_2ADDR:
+ case Instruction::SUB_INT:
+ case Instruction::SUB_INT_2ADDR:
+ // The code below is consistent with the implementation of OpRegRegImm().
+ {
+ int32_t abs_value = std::abs(value);
+ if (abs_value < 0x1000) {
+ return true;
+ } else if ((abs_value & UINT64_C(0xfff)) == 0 && ((abs_value >> 12) < 0x1000)) {
+ return true;
+ }
+ return false;
+ }
+ case Instruction::SHL_INT:
+ case Instruction::SHL_INT_2ADDR:
+ case Instruction::SHR_INT:
+ case Instruction::SHR_INT_2ADDR:
+ case Instruction::USHR_INT:
+ case Instruction::USHR_INT_2ADDR:
+ return true;
+ case Instruction::AND_INT:
+ case Instruction::AND_INT_2ADDR:
+ case Instruction::AND_INT_LIT16:
+ case Instruction::AND_INT_LIT8:
+ case Instruction::OR_INT:
+ case Instruction::OR_INT_2ADDR:
+ case Instruction::OR_INT_LIT16:
+ case Instruction::OR_INT_LIT8:
+ case Instruction::XOR_INT:
+ case Instruction::XOR_INT_2ADDR:
+ case Instruction::XOR_INT_LIT16:
+ case Instruction::XOR_INT_LIT8:
+ if (value == 0 || value == INT32_C(-1)) {
+ return true;
+ }
+ return (EncodeLogicalImmediate(/*is_wide=*/false, value) >= 0);
+ default:
+ return false;
+ }
+}
+
/*
* Load a immediate using one single instruction when possible; otherwise
* use a pair of movz and movk instructions.
@@ -358,9 +454,6 @@ LIR* Arm64Mir2Lir::LoadConstantNoClobber(RegStorage r_dest, int value) {
// TODO: clean up the names. LoadConstantWide() should really be LoadConstantNoClobberWide().
LIR* Arm64Mir2Lir::LoadConstantWide(RegStorage r_dest, int64_t value) {
- // Maximum number of instructions to use for encoding the immediate.
- const int max_num_ops = 2;
-
if (r_dest.IsFloat()) {
return LoadFPConstantValueWide(r_dest, value);
}
@@ -378,19 +471,12 @@ LIR* Arm64Mir2Lir::LoadConstantWide(RegStorage r_dest, int64_t value) {
}
// At least one in value's halfwords is not 0x0, nor 0xffff: find out how many.
- int num_0000_halfwords = 0;
- int num_ffff_halfwords = 0;
uint64_t uvalue = static_cast<uint64_t>(value);
- for (int shift = 0; shift < 64; shift += 16) {
- uint16_t halfword = static_cast<uint16_t>(uvalue >> shift);
- if (halfword == 0)
- num_0000_halfwords++;
- else if (halfword == UINT16_C(0xffff))
- num_ffff_halfwords++;
- }
- int num_fast_halfwords = std::max(num_0000_halfwords, num_ffff_halfwords);
+ int num_fast_halfwords = GetNumFastHalfWords(uvalue);
+ int num_slow_halfwords = 4 - (num_fast_halfwords & 0x7);
+ bool more_ffff_halfwords = (num_fast_halfwords & 0x8) != 0;
- if (num_fast_halfwords < 3) {
+ if (num_slow_halfwords > 1) {
// A single movz/movn is not enough. Try the logical immediate route.
int log_imm = EncodeLogicalImmediate(/*is_wide=*/true, value);
if (log_imm >= 0) {
@@ -398,19 +484,19 @@ LIR* Arm64Mir2Lir::LoadConstantWide(RegStorage r_dest, int64_t value) {
}
}
- if (num_fast_halfwords >= 4 - max_num_ops) {
+ if (num_slow_halfwords <= max_num_ops_per_const_load) {
// We can encode the number using a movz/movn followed by one or more movk.
ArmOpcode op;
uint16_t background;
LIR* res = nullptr;
// Decide whether to use a movz or a movn.
- if (num_0000_halfwords >= num_ffff_halfwords) {
- op = WIDE(kA64Movz3rdM);
- background = 0;
- } else {
+ if (more_ffff_halfwords) {
op = WIDE(kA64Movn3rdM);
background = 0xffff;
+ } else {
+ op = WIDE(kA64Movz3rdM);
+ background = 0;
}
// Emit the first instruction (movz, movn).
@@ -726,7 +812,7 @@ LIR* Arm64Mir2Lir::OpRegRegImm64(OpKind op, RegStorage r_dest, RegStorage r_src1
int64_t abs_value = (neg) ? -value : value;
ArmOpcode opcode = kA64Brk1d;
ArmOpcode alt_opcode = kA64Brk1d;
- int32_t log_imm = -1;
+ bool is_logical = false;
bool is_wide = r_dest.Is64Bit();
ArmOpcode wide = (is_wide) ? WIDE(0) : UNWIDE(0);
int info = 0;
@@ -761,65 +847,89 @@ LIR* Arm64Mir2Lir::OpRegRegImm64(OpKind op, RegStorage r_dest, RegStorage r_src1
opcode = (neg) ? kA64Add4RRdT : kA64Sub4RRdT;
return NewLIR4(opcode | wide, r_dest.GetReg(), r_src1.GetReg(), abs_value >> 12, 1);
} else {
- log_imm = -1;
alt_opcode = (op == kOpAdd) ? kA64Add4RRre : kA64Sub4RRre;
info = EncodeExtend(is_wide ? kA64Uxtx : kA64Uxtw, 0);
}
break;
- // case kOpRsub:
- // opcode = kThumb2RsubRRI8M;
- // alt_opcode = kThumb2RsubRRR;
- // break;
case kOpAdc:
- log_imm = -1;
alt_opcode = kA64Adc3rrr;
break;
case kOpSbc:
- log_imm = -1;
alt_opcode = kA64Sbc3rrr;
break;
case kOpOr:
- log_imm = EncodeLogicalImmediate(is_wide, value);
+ is_logical = true;
opcode = kA64Orr3Rrl;
alt_opcode = kA64Orr4rrro;
break;
case kOpAnd:
- log_imm = EncodeLogicalImmediate(is_wide, value);
+ is_logical = true;
opcode = kA64And3Rrl;
alt_opcode = kA64And4rrro;
break;
case kOpXor:
- log_imm = EncodeLogicalImmediate(is_wide, value);
+ is_logical = true;
opcode = kA64Eor3Rrl;
alt_opcode = kA64Eor4rrro;
break;
case kOpMul:
// TUNING: power of 2, shift & add
- log_imm = -1;
alt_opcode = kA64Mul3rrr;
break;
default:
LOG(FATAL) << "Bad opcode: " << op;
}
- if (log_imm >= 0) {
- return NewLIR3(opcode | wide, r_dest.GetReg(), r_src1.GetReg(), log_imm);
- } else {
- RegStorage r_scratch;
- if (is_wide) {
- r_scratch = AllocTempWide();
- LoadConstantWide(r_scratch, value);
+ if (is_logical) {
+ int log_imm = EncodeLogicalImmediate(is_wide, value);
+ if (log_imm >= 0) {
+ return NewLIR3(opcode | wide, r_dest.GetReg(), r_src1.GetReg(), log_imm);
} else {
- r_scratch = AllocTemp();
- LoadConstant(r_scratch, value);
+ // When the immediate is either 0 or ~0, the logical operation can be trivially reduced
+ // to a - possibly negated - assignment.
+ if (value == 0) {
+ switch (op) {
+ case kOpOr:
+ case kOpXor:
+ // Or/Xor by zero reduces to an assignment.
+ return NewLIR2(kA64Mov2rr | wide, r_dest.GetReg(), r_src1.GetReg());
+ default:
+ // And by zero reduces to a `mov rdest, xzr'.
+ DCHECK(op == kOpAnd);
+ return NewLIR2(kA64Mov2rr | wide, r_dest.GetReg(), (is_wide) ? rxzr : rwzr);
+ }
+ } else if (value == INT64_C(-1)
+ || (!is_wide && static_cast<uint32_t>(value) == ~UINT32_C(0))) {
+ switch (op) {
+ case kOpAnd:
+ // And by -1 reduces to an assignment.
+ return NewLIR2(kA64Mov2rr | wide, r_dest.GetReg(), r_src1.GetReg());
+ case kOpXor:
+ // Xor by -1 reduces to an `mvn rdest, rsrc'.
+ return NewLIR2(kA64Mvn2rr | wide, r_dest.GetReg(), r_src1.GetReg());
+ default:
+ // Or by -1 reduces to a `mvn rdest, xzr'.
+ DCHECK(op == kOpOr);
+ return NewLIR2(kA64Mvn2rr | wide, r_dest.GetReg(), (is_wide) ? rxzr : rwzr);
+ }
+ }
}
- if (EncodingMap[alt_opcode].flags & IS_QUAD_OP)
- res = NewLIR4(alt_opcode | wide, r_dest.GetReg(), r_src1.GetReg(), r_scratch.GetReg(), info);
- else
- res = NewLIR3(alt_opcode | wide, r_dest.GetReg(), r_src1.GetReg(), r_scratch.GetReg());
- FreeTemp(r_scratch);
- return res;
}
+
+ RegStorage r_scratch;
+ if (is_wide) {
+ r_scratch = AllocTempWide();
+ LoadConstantWide(r_scratch, value);
+ } else {
+ r_scratch = AllocTemp();
+ LoadConstant(r_scratch, value);
+ }
+ if (EncodingMap[alt_opcode].flags & IS_QUAD_OP)
+ res = NewLIR4(alt_opcode | wide, r_dest.GetReg(), r_src1.GetReg(), r_scratch.GetReg(), info);
+ else
+ res = NewLIR3(alt_opcode | wide, r_dest.GetReg(), r_src1.GetReg(), r_scratch.GetReg());
+ FreeTemp(r_scratch);
+ return res;
}
LIR* Arm64Mir2Lir::OpRegImm(OpKind op, RegStorage r_dest_src1, int value) {
generated by cgit v1.2.3 (git 2.25.1) at 2025-06-21 15:19:03 +0000