Reviewers: Paul Lind, kisg, kilvadyb, danno, ulan, Rodolph Perfetta,
Message:
PTAL.
Description:
MIPS: Tweak Math.exp.
Port r16913 (a1b66fea)
Original commit message:
Avoid corrupting the input and small assembly tuning.
BUG=
Please review this at https://codereview.chromium.org/24654002/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+39, -23 lines):
M src/mips/codegen-mips.h
M src/mips/codegen-mips.cc
M src/mips/lithium-mips.cc
Index: src/mips/codegen-mips.cc
diff --git a/src/mips/codegen-mips.cc b/src/mips/codegen-mips.cc
index
a12faee433a8bb70dbaa09e131c90d836c24c73a..a264ac477c83557dfa00a36b44d4982af0092827
100644
--- a/src/mips/codegen-mips.cc
+++ b/src/mips/codegen-mips.cc
@@ -540,52 +540,67 @@ void MathExpGenerator::EmitMathExp(MacroAssembler*
masm,
ASSERT(!temp2.is(temp3));
ASSERT(ExternalReference::math_exp_constants(0).address() != NULL);
- Label done;
+ Label zero, infinity, done;
__ li(temp3, Operand(ExternalReference::math_exp_constants(0)));
__ ldc1(double_scratch1, ExpConstant(0, temp3));
- __ Move(result, kDoubleRegZero);
- __ BranchF(&done, NULL, ge, double_scratch1, input);
+ __ BranchF(&zero, NULL, ge, double_scratch1, input);
+
__ ldc1(double_scratch2, ExpConstant(1, temp3));
- __ ldc1(result, ExpConstant(2, temp3));
- __ BranchF(&done, NULL, ge, input, double_scratch2);
+ __ BranchF(&infinity, NULL, ge, input, double_scratch2);
+
__ ldc1(double_scratch1, ExpConstant(3, temp3));
__ ldc1(result, ExpConstant(4, temp3));
__ mul_d(double_scratch1, double_scratch1, input);
__ add_d(double_scratch1, double_scratch1, result);
- __ Move(temp2, temp1, double_scratch1);
+ __ FmoveLow(temp2, double_scratch1);
__ sub_d(double_scratch1, double_scratch1, result);
__ ldc1(result, ExpConstant(6, temp3));
__ ldc1(double_scratch2, ExpConstant(5, temp3));
__ mul_d(double_scratch1, double_scratch1, double_scratch2);
__ sub_d(double_scratch1, double_scratch1, input);
__ sub_d(result, result, double_scratch1);
- __ mul_d(input, double_scratch1, double_scratch1);
- __ mul_d(result, result, input);
- __ srl(temp1, temp2, 11);
+ __ mul_d(double_scratch2, double_scratch1, double_scratch1);
+ __ mul_d(result, result, double_scratch2);
__ ldc1(double_scratch2, ExpConstant(7, temp3));
__ mul_d(result, result, double_scratch2);
__ sub_d(result, result, double_scratch1);
- __ ldc1(double_scratch2, ExpConstant(8, temp3));
+ // Mov 1 in double_scratch2 as math_exp_constants_array[8] == 1.
+ ASSERT(*reinterpret_cast<double*>
+ (ExternalReference::math_exp_constants(8).address()) == 1);
+ __ Move(double_scratch2, 1);
__ add_d(result, result, double_scratch2);
- __ li(at, 0x7ff);
- __ And(temp2, temp2, at);
+ __ srl(temp1, temp2, 11);
+ __ Ext(temp2, temp2, 0, 11);
__ Addu(temp1, temp1, Operand(0x3ff));
- __ sll(temp1, temp1, 20);
// Must not call ExpConstant() after overwriting temp3!
__ li(temp3, Operand(ExternalReference::math_exp_log_table()));
__ sll(at, temp2, 3);
- __ addu(at, at, temp3);
- __ lw(at, MemOperand(at));
- __ Addu(temp3, temp3, Operand(kPointerSize));
- __ sll(temp2, temp2, 3);
- __ addu(temp2, temp2, temp3);
- __ lw(temp2, MemOperand(temp2));
- __ Or(temp1, temp1, temp2);
- __ Move(input, at, temp1);
- __ mul_d(result, result, input);
+ __ Addu(temp3, temp3, Operand(at));
+ __ lw(temp2, MemOperand(temp3, 0));
+ __ lw(temp3, MemOperand(temp3, kPointerSize));
+ // The first word is loaded is the lower number register.
+ if (temp2.code() < temp3.code()) {
+ __ sll(at, temp1, 20);
+ __ Or(temp1, temp3, at);
+ __ Move(double_scratch1, temp2, temp1);
+ } else {
+ __ sll(at, temp1, 20);
+ __ Or(temp1, temp2, at);
+ __ Move(double_scratch1, temp3, temp1);
+ }
+ __ mul_d(result, result, double_scratch1);
+ __ Branch(&done);
+
+ __ bind(&zero);
+ __ Move(result, kDoubleRegZero);
+ __ Branch(&done);
+
+ __ bind(&infinity);
+ __ ldc1(result, ExpConstant(2, temp3));
+
__ bind(&done);
}
Index: src/mips/codegen-mips.h
diff --git a/src/mips/codegen-mips.h b/src/mips/codegen-mips.h
index
32d7d0d65c7135a41eb145e64bf960687578c0a1..822b94ad7998629412cbdffef081c2e4ab9e8938
100644
--- a/src/mips/codegen-mips.h
+++ b/src/mips/codegen-mips.h
@@ -99,6 +99,7 @@ class StringCharLoadGenerator : public AllStatic {
class MathExpGenerator : public AllStatic {
public:
+ // Register input isn't modified. All other registers are clobbered.
static void EmitMathExp(MacroAssembler* masm,
DoubleRegister input,
DoubleRegister result,
Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index
7333398176b11d4c035fa41f37a157d6f12b516e..730c1d0dc395e41e48dfd0b6c036ea4b49c10e53
100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1218,7 +1218,7 @@ LInstruction*
LChunkBuilder::DoMathTan(HUnaryMathOperation* instr) {
LInstruction* LChunkBuilder::DoMathExp(HUnaryMathOperation* instr) {
ASSERT(instr->representation().IsDouble());
ASSERT(instr->value()->representation().IsDouble());
- LOperand* input = UseTempRegister(instr->value());
+ LOperand* input = UseRegister(instr->value());
LOperand* temp1 = TempRegister();
LOperand* temp2 = TempRegister();
LOperand* double_temp = FixedTemp(f6); // Chosen by fair dice roll.
--
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