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Unified Diff: src/x64/lithium-codegen-x64.cc

Issue 212703002: Consistently use a separate Lithium instruction for flooring division. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Added TODOs Created 6 years, 9 months ago
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Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 4be8657027567489b97880478e232bcdc46e1c38..f39ecad915ba283fe18a7774ad01c855902e1be8 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -1205,6 +1205,59 @@ void LCodeGen::DoFlooringDivByConstI(LFlooringDivByConstI* instr) {
}
+// TODO(svenpanne) Refactor this to avoid code duplication with DoDivI.
+void LCodeGen::DoFlooringDivI(LFlooringDivI* instr) {
+ HBinaryOperation* hdiv = instr->hydrogen();
+ Register dividend = ToRegister(instr->dividend());
+ Register divisor = ToRegister(instr->divisor());
+ Register remainder = ToRegister(instr->temp());
+ Register result = ToRegister(instr->result());
+ ASSERT(dividend.is(rax));
+ ASSERT(remainder.is(rdx));
+ ASSERT(result.is(rax));
+ ASSERT(!divisor.is(rax));
+ ASSERT(!divisor.is(rdx));
+
+ // Check for x / 0.
+ if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
+ __ testl(divisor, divisor);
+ DeoptimizeIf(zero, instr->environment());
+ }
+
+ // Check for (0 / -x) that will produce negative zero.
+ if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
+ Label dividend_not_zero;
+ __ testl(dividend, dividend);
+ __ j(not_zero, &dividend_not_zero, Label::kNear);
+ __ testl(divisor, divisor);
+ DeoptimizeIf(sign, instr->environment());
+ __ bind(&dividend_not_zero);
+ }
+
+ // Check for (kMinInt / -1).
+ if (hdiv->CheckFlag(HValue::kCanOverflow)) {
+ Label dividend_not_min_int;
+ __ cmpl(dividend, Immediate(kMinInt));
+ __ j(not_zero, &dividend_not_min_int, Label::kNear);
+ __ cmpl(divisor, Immediate(-1));
+ DeoptimizeIf(zero, instr->environment());
+ __ bind(&dividend_not_min_int);
+ }
+
+ // Sign extend to rdx (= remainder).
+ __ cdq();
+ __ idivl(divisor);
+
+ Label done;
+ __ testl(remainder, remainder);
+ __ j(zero, &done, Label::kNear);
+ __ xorl(remainder, divisor);
+ __ sarl(remainder, Immediate(31));
+ __ addl(result, remainder);
+ __ bind(&done);
+}
+
+
void LCodeGen::DoDivByPowerOf2I(LDivByPowerOf2I* instr) {
Register dividend = ToRegister(instr->dividend());
int32_t divisor = instr->divisor();
@@ -1272,10 +1325,11 @@ void LCodeGen::DoDivByConstI(LDivByConstI* instr) {
}
+// TODO(svenpanne) Refactor this to avoid code duplication with DoFlooringDivI.
void LCodeGen::DoDivI(LDivI* instr) {
HBinaryOperation* hdiv = instr->hydrogen();
- Register dividend = ToRegister(instr->left());
- Register divisor = ToRegister(instr->right());
+ Register dividend = ToRegister(instr->dividend());
+ Register divisor = ToRegister(instr->divisor());
Register remainder = ToRegister(instr->temp());
Register result = ToRegister(instr->result());
ASSERT(dividend.is(rax));
@@ -1314,15 +1368,7 @@ void LCodeGen::DoDivI(LDivI* instr) {
__ cdq();
__ idivl(divisor);
- if (hdiv->IsMathFloorOfDiv()) {
- Label done;
- __ testl(remainder, remainder);
- __ j(zero, &done, Label::kNear);
- __ xorl(remainder, divisor);
- __ sarl(remainder, Immediate(31));
- __ addl(result, remainder);
- __ bind(&done);
- } else if (!hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
+ if (!hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
// Deoptimize if remainder is not 0.
__ testl(remainder, remainder);
DeoptimizeIf(not_zero, instr->environment());
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