Revision: 20417
Author: [email protected]
Date: Tue Apr 1 23:43:47 2014 UTC
Log: MIPS: Consistently use a separate Lithium instruction for
flooring division.
Port r20395 (5b802048)
Original commit message:
Previously we tried to share some code on by a slightly confusing re-use
of LDivI for a (general) flooring division. Now we cleanly separate
concerns, just like for the rest of the division-like operations. Note
that ARM64 already did it this way.
If we really want to save some code, we can introduce some macro
assembler instructions and/or helper functions in the code generator in
a future CL, but we should really try to avoid being "clever" to save
just a few lines of trivial code. Effort != complexity. :-)
Renamed some related Lithium operands on the way for more consistency.
BUG=
[email protected]
Review URL: https://codereview.chromium.org/220403009
http://code.google.com/p/v8/source/detail?r=20417
Modified:
/branches/bleeding_edge/src/mips/lithium-codegen-mips.cc
/branches/bleeding_edge/src/mips/lithium-mips.cc
/branches/bleeding_edge/src/mips/lithium-mips.h
=======================================
--- /branches/bleeding_edge/src/mips/lithium-codegen-mips.cc Tue Apr 1
09:20:28 2014 UTC
+++ /branches/bleeding_edge/src/mips/lithium-codegen-mips.cc Tue Apr 1
23:43:47 2014 UTC
@@ -1242,26 +1242,27 @@
}
+// TODO(svenpanne) Refactor this to avoid code duplication with
DoFlooringDivI.
void LCodeGen::DoDivI(LDivI* instr) {
HBinaryOperation* hdiv = instr->hydrogen();
- const Register left = ToRegister(instr->left());
- const Register right = ToRegister(instr->right());
+ Register dividend = ToRegister(instr->dividend());
+ Register divisor = ToRegister(instr->divisor());
const Register result = ToRegister(instr->result());
// On MIPS div is asynchronous - it will run in the background while we
// check for special cases.
- __ div(left, right);
+ __ div(dividend, divisor);
// Check for x / 0.
if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
- DeoptimizeIf(eq, instr->environment(), right, Operand(zero_reg));
+ DeoptimizeIf(eq, instr->environment(), divisor, Operand(zero_reg));
}
// Check for (0 / -x) that will produce negative zero.
if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
Label left_not_zero;
- __ Branch(&left_not_zero, ne, left, Operand(zero_reg));
- DeoptimizeIf(lt, instr->environment(), right, Operand(zero_reg));
+ __ Branch(&left_not_zero, ne, dividend, Operand(zero_reg));
+ DeoptimizeIf(lt, instr->environment(), divisor, Operand(zero_reg));
__ bind(&left_not_zero);
}
@@ -1269,23 +1270,12 @@
if (hdiv->CheckFlag(HValue::kCanOverflow) &&
!hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
Label left_not_min_int;
- __ Branch(&left_not_min_int, ne, left, Operand(kMinInt));
- DeoptimizeIf(eq, instr->environment(), right, Operand(-1));
+ __ Branch(&left_not_min_int, ne, dividend, Operand(kMinInt));
+ DeoptimizeIf(eq, instr->environment(), divisor, Operand(-1));
__ bind(&left_not_min_int);
}
- if (hdiv->IsMathFloorOfDiv()) {
- // We performed a truncating division. Correct the result if necessary.
- Label done;
- Register remainder = scratch0();
- __ mfhi(remainder);
- __ mflo(result);
- __ Branch(&done, eq, remainder, Operand(zero_reg), USE_DELAY_SLOT);
- __ Xor(remainder, remainder, Operand(right));
- __ Branch(&done, ge, remainder, Operand(zero_reg));
- __ Subu(result, result, Operand(1));
- __ bind(&done);
- } else if (!hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
+ if (!hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
__ mfhi(result);
DeoptimizeIf(ne, instr->environment(), result, Operand(zero_reg));
__ mflo(result);
@@ -1396,6 +1386,52 @@
__ Subu(result, result, Operand(1));
__ bind(&done);
}
+
+
+// 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());
+ const Register result = ToRegister(instr->result());
+
+ // On MIPS div is asynchronous - it will run in the background while we
+ // check for special cases.
+ __ div(dividend, divisor);
+
+ // Check for x / 0.
+ if (hdiv->CheckFlag(HValue::kCanBeDivByZero)) {
+ DeoptimizeIf(eq, instr->environment(), divisor, Operand(zero_reg));
+ }
+
+ // Check for (0 / -x) that will produce negative zero.
+ if (hdiv->CheckFlag(HValue::kBailoutOnMinusZero)) {
+ Label left_not_zero;
+ __ Branch(&left_not_zero, ne, dividend, Operand(zero_reg));
+ DeoptimizeIf(lt, instr->environment(), divisor, Operand(zero_reg));
+ __ bind(&left_not_zero);
+ }
+
+ // Check for (kMinInt / -1).
+ if (hdiv->CheckFlag(HValue::kCanOverflow) &&
+ !hdiv->CheckFlag(HValue::kAllUsesTruncatingToInt32)) {
+ Label left_not_min_int;
+ __ Branch(&left_not_min_int, ne, dividend, Operand(kMinInt));
+ DeoptimizeIf(eq, instr->environment(), divisor, Operand(-1));
+ __ bind(&left_not_min_int);
+ }
+
+ // We performed a truncating division. Correct the result if necessary.
+ Label done;
+ Register remainder = scratch0();
+ __ mfhi(remainder);
+ __ mflo(result);
+ __ Branch(&done, eq, remainder, Operand(zero_reg), USE_DELAY_SLOT);
+ __ Xor(remainder, remainder, Operand(divisor));
+ __ Branch(&done, ge, remainder, Operand(zero_reg));
+ __ Subu(result, result, Operand(1));
+ __ bind(&done);
+}
void LCodeGen::DoMulI(LMulI* instr) {
=======================================
--- /branches/bleeding_edge/src/mips/lithium-mips.cc Tue Apr 1 23:42:55
2014 UTC
+++ /branches/bleeding_edge/src/mips/lithium-mips.cc Tue Apr 1 23:43:47
2014 UTC
@@ -1295,7 +1295,7 @@
}
-LInstruction* LChunkBuilder::DoDivI(HBinaryOperation* instr) {
+LInstruction* LChunkBuilder::DoDivI(HDiv* instr) {
ASSERT(instr->representation().IsSmiOrInteger32());
ASSERT(instr->left()->representation().Equals(instr->representation()));
ASSERT(instr->right()->representation().Equals(instr->representation()));
@@ -1363,6 +1363,17 @@
}
return result;
}
+
+
+LInstruction* LChunkBuilder::DoFlooringDivI(HMathFloorOfDiv* instr) {
+ ASSERT(instr->representation().IsSmiOrInteger32());
+ ASSERT(instr->left()->representation().Equals(instr->representation()));
+ ASSERT(instr->right()->representation().Equals(instr->representation()));
+ LOperand* dividend = UseRegister(instr->left());
+ LOperand* divisor = UseRegister(instr->right());
+ LFlooringDivI* div = new(zone()) LFlooringDivI(dividend, divisor);
+ return AssignEnvironment(DefineAsRegister(div));
+}
LInstruction* LChunkBuilder::DoMathFloorOfDiv(HMathFloorOfDiv* instr) {
@@ -1371,7 +1382,7 @@
} else if (instr->right()->IsConstant()) {
return DoFlooringDivByConstI(instr);
} else {
- return DoDivI(instr);
+ return DoFlooringDivI(instr);
}
}
=======================================
--- /branches/bleeding_edge/src/mips/lithium-mips.h Thu Mar 20 16:04:51
2014 UTC
+++ /branches/bleeding_edge/src/mips/lithium-mips.h Tue Apr 1 23:43:47
2014 UTC
@@ -97,6 +97,7 @@
V(DummyUse) \
V(FlooringDivByConstI) \
V(FlooringDivByPowerOf2I) \
+ V(FlooringDivI) \
V(ForInCacheArray) \
V(ForInPrepareMap) \
V(FunctionLiteral) \
@@ -709,13 +710,13 @@
class LDivI V8_FINAL : public LTemplateInstruction<1, 2, 0> {
public:
- LDivI(LOperand* left, LOperand* right) {
- inputs_[0] = left;
- inputs_[1] = right;
+ LDivI(LOperand* dividend, LOperand* divisor) {
+ inputs_[0] = dividend;
+ inputs_[1] = divisor;
}
- LOperand* left() { return inputs_[0]; }
- LOperand* right() { return inputs_[1]; }
+ LOperand* dividend() { return inputs_[0]; }
+ LOperand* divisor() { return inputs_[1]; }
DECLARE_CONCRETE_INSTRUCTION(DivI, "div-i")
DECLARE_HYDROGEN_ACCESSOR(BinaryOperation)
@@ -761,6 +762,21 @@
};
+class LFlooringDivI V8_FINAL : public LTemplateInstruction<1, 2, 0> {
+ public:
+ LFlooringDivI(LOperand* dividend, LOperand* divisor) {
+ inputs_[0] = dividend;
+ inputs_[1] = divisor;
+ }
+
+ LOperand* dividend() { return inputs_[0]; }
+ LOperand* divisor() { return inputs_[1]; }
+
+ DECLARE_CONCRETE_INSTRUCTION(FlooringDivI, "flooring-div-i")
+ DECLARE_HYDROGEN_ACCESSOR(MathFloorOfDiv)
+};
+
+
class LMulI V8_FINAL : public LTemplateInstruction<1, 2, 0> {
public:
LMulI(LOperand* left, LOperand* right) {
@@ -2679,12 +2695,13 @@
LInstruction* DoMathClz32(HUnaryMathOperation* instr);
LInstruction* DoDivByPowerOf2I(HDiv* instr);
LInstruction* DoDivByConstI(HDiv* instr);
- LInstruction* DoDivI(HBinaryOperation* instr);
+ LInstruction* DoDivI(HDiv* instr);
LInstruction* DoModByPowerOf2I(HMod* instr);
LInstruction* DoModByConstI(HMod* instr);
LInstruction* DoModI(HMod* instr);
LInstruction* DoFlooringDivByPowerOf2I(HMathFloorOfDiv* instr);
LInstruction* DoFlooringDivByConstI(HMathFloorOfDiv* instr);
+ LInstruction* DoFlooringDivI(HMathFloorOfDiv* instr);
private:
enum Status {
--
--
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