Reviewers: ulan,
Message:
further breakdown from issue 23156006
Description:
ARM: Tweak Math.exp.
Avoid corrupting the input and small assembly tuning.
BUG=none
TEST=test/mjsunit/lithium/MathExp.js
Please review this at https://codereview.chromium.org/24278004/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+42, -27 lines):
M src/arm/codegen-arm.h
M src/arm/codegen-arm.cc
M src/arm/lithium-arm.cc
A + test/mjsunit/lithium/MathExp.js
Index: src/arm/codegen-arm.cc
diff --git a/src/arm/codegen-arm.cc b/src/arm/codegen-arm.cc
index
5b80d6facc5ea8e4a0b2fb6fcf985a83bdbc1cba..57e227d86949e5085bef9bc9fbc8e7b1aa123990
100644
--- a/src/arm/codegen-arm.cc
+++ b/src/arm/codegen-arm.cc
@@ -775,50 +775,63 @@ void MathExpGenerator::EmitMathExp(MacroAssembler*
masm,
ASSERT(!temp2.is(temp3));
ASSERT(ExternalReference::math_exp_constants(0).address() != NULL);
- Label done;
+ Label zero, infinity, done;
__ mov(temp3, Operand(ExternalReference::math_exp_constants(0)));
__ vldr(double_scratch1, ExpConstant(0, temp3));
- __ vmov(result, kDoubleRegZero);
__ VFPCompareAndSetFlags(double_scratch1, input);
- __ b(ge, &done);
+ __ b(ge, &zero);
+
__ vldr(double_scratch2, ExpConstant(1, temp3));
__ VFPCompareAndSetFlags(input, double_scratch2);
- __ vldr(result, ExpConstant(2, temp3));
- __ b(ge, &done);
+ __ b(ge, &infinity);
+
__ vldr(double_scratch1, ExpConstant(3, temp3));
__ vldr(result, ExpConstant(4, temp3));
__ vmul(double_scratch1, double_scratch1, input);
__ vadd(double_scratch1, double_scratch1, result);
- __ vmov(temp2, temp1, double_scratch1);
+ __ VmovLow(temp2, double_scratch1);
__ vsub(double_scratch1, double_scratch1, result);
__ vldr(result, ExpConstant(6, temp3));
__ vldr(double_scratch2, ExpConstant(5, temp3));
__ vmul(double_scratch1, double_scratch1, double_scratch2);
__ vsub(double_scratch1, double_scratch1, input);
__ vsub(result, result, double_scratch1);
- __ vmul(input, double_scratch1, double_scratch1);
- __ vmul(result, result, input);
- __ mov(temp1, Operand(temp2, LSR, 11));
+ __ vmul(double_scratch2, double_scratch1, double_scratch1);
+ __ vmul(result, result, double_scratch2);
__ vldr(double_scratch2, ExpConstant(7, temp3));
__ vmul(result, result, double_scratch2);
__ vsub(result, result, double_scratch1);
- __ vldr(double_scratch2, ExpConstant(8, temp3));
+ // Mov 1 in double_scratch2 as math_exp_constants_array[8] == 1.
+ __ vmov(double_scratch2, 1);
__ vadd(result, result, double_scratch2);
- __ movw(ip, 0x7ff);
- __ and_(temp2, temp2, Operand(ip));
+ __ mov(temp1, Operand(temp2, LSR, 11));
+ __ Ubfx(temp2, temp2, 0, 11);
__ add(temp1, temp1, Operand(0x3ff));
- __ mov(temp1, Operand(temp1, LSL, 20));
// Must not call ExpConstant() after overwriting temp3!
__ mov(temp3, Operand(ExternalReference::math_exp_log_table()));
- __ ldr(ip, MemOperand(temp3, temp2, LSL, 3));
- __ add(temp3, temp3, Operand(kPointerSize));
- __ ldr(temp2, MemOperand(temp3, temp2, LSL, 3));
- __ orr(temp1, temp1, temp2);
- __ vmov(input, ip, temp1);
- __ vmul(result, result, input);
+ __ add(temp3, temp3, Operand(temp2, LSL, 3));
+ __ ldm(ia, temp3, temp2.bit() | temp3.bit());
+ // The first word is loaded is the lower number register.
+ if (temp2.code() < temp3.code()) {
+ __ orr(temp1, temp3, Operand(temp1, LSL, 20));
+ __ vmov(double_scratch1, temp2, temp1);
+ } else {
+ __ orr(temp1, temp2, Operand(temp1, LSL, 20));
+ __ vmov(double_scratch1, temp3, temp1);
+ }
+ __ vmul(result, result, double_scratch1);
+ __ b(&done);
+
+ __ bind(&zero);
+ __ vmov(result, kDoubleRegZero);
+ __ b(&done);
+
+ __ bind(&infinity);
+ __ vldr(result, ExpConstant(2, temp3));
+
__ bind(&done);
}
Index: src/arm/codegen-arm.h
diff --git a/src/arm/codegen-arm.h b/src/arm/codegen-arm.h
index
54530d87262df1577603039e1840e5f501c0bbd7..ecbe64cbad304d8f7eb5d875f99ea3e7e5ad7a61
100644
--- a/src/arm/codegen-arm.h
+++ b/src/arm/codegen-arm.h
@@ -97,6 +97,7 @@ class StringCharLoadGenerator : public AllStatic {
class MathExpGenerator : public AllStatic {
public:
+ // Register input isn't modified. All other registers are clobbered.
static void EmitMathExp(MacroAssembler* masm,
DwVfpRegister input,
DwVfpRegister result,
Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index
f216a8e094d409bc80c5b492bd27744ab08d94f9..6fdbbb58934c0e852df086b589f55edab6f85905
100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -1240,7 +1240,7 @@ 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(d3); // Chosen by fair dice roll.
Index: test/mjsunit/lithium/MathExp.js
diff --git a/test/mjsunit/compiler/type-feedback-after-throw.js
b/test/mjsunit/lithium/MathExp.js
similarity index 92%
copy from test/mjsunit/compiler/type-feedback-after-throw.js
copy to test/mjsunit/lithium/MathExp.js
index
891e315c5c1121fb1674ee4094890266a7708889..854ff5fd7fd2a7a22bcc3557e4e2bb4c01d9b83f
100644
--- a/test/mjsunit/compiler/type-feedback-after-throw.js
+++ b/test/mjsunit/lithium/MathExp.js
@@ -27,12 +27,13 @@
// Flags: --allow-natives-syntax
-function foo() {
- throw "Error";
- return 1 > 5;
-};
+function foo(x) {
+ return Math.exp(x);
+}
-try { foo() } catch(e) {}
-try { foo() } catch(e) {}
+foo(12.3);
+var r1 = foo(12.3);
%OptimizeFunctionOnNextCall(foo);
-try { foo() } catch(e) {}
+var r2 = foo(12.3);
+
+assertEquals(r1, r2);
--
--
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