Reviewers: danno,
Message:
PTAL.
Description:
Tweak SmiSub for X64
Please review this at https://codereview.chromium.org/24965002/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+53, -44 lines):
M src/x64/macro-assembler-x64.h
M src/x64/macro-assembler-x64.cc
Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index
96fa4fc49630424093eaa29874c118e95c34a115..6a7ca602a3e8d24f5e9eacbf9a74b705dd2c8f95
100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -1699,34 +1699,37 @@ void MacroAssembler::SmiAdd(Register dst,
}
-void MacroAssembler::SmiSub(Register dst,
- Register src1,
- Register src2,
- Label* on_not_smi_result,
- Label::Distance near_jump) {
- ASSERT_NOT_NULL(on_not_smi_result);
- ASSERT(!dst.is(src2));
+template<class T>
+static void SmiSubHelper(MacroAssembler* masm,
+ Register dst,
+ Register src1,
+ T src2,
+ Label* on_not_smi_result,
+ Label::Distance near_jump) {
if (dst.is(src1)) {
- cmpq(dst, src2);
- j(overflow, on_not_smi_result, near_jump);
- subq(dst, src2);
+ Label done;
+ masm->subq(dst, src2);
+ masm->j(no_overflow, &done, Label::kNear);
+ // Restore src1.
+ masm->addq(dst, src2);
+ masm->jmp(on_not_smi_result, near_jump);
+ masm->bind(&done);
} else {
- movq(dst, src1);
- subq(dst, src2);
- j(overflow, on_not_smi_result, near_jump);
+ masm->movq(dst, src1);
+ masm->subq(dst, src2);
+ masm->j(overflow, on_not_smi_result, near_jump);
}
}
-void MacroAssembler::SmiSub(Register dst, Register src1, Register src2) {
- // No overflow checking. Use only when it's known that
- // overflowing is impossible (e.g., subtracting two positive smis).
+void MacroAssembler::SmiSub(Register dst,
+ Register src1,
+ Register src2,
+ Label* on_not_smi_result,
+ Label::Distance near_jump) {
+ ASSERT_NOT_NULL(on_not_smi_result);
ASSERT(!dst.is(src2));
- if (!dst.is(src1)) {
- movq(dst, src1);
- }
- subq(dst, src2);
- Assert(no_overflow, kSmiSubtractionOverflow);
+ SmiSubHelper<Register>(this, dst, src1, src2, on_not_smi_result,
near_jump);
}
@@ -1736,29 +1739,36 @@ void MacroAssembler::SmiSub(Register dst,
Label* on_not_smi_result,
Label::Distance near_jump) {
ASSERT_NOT_NULL(on_not_smi_result);
- if (dst.is(src1)) {
- movq(kScratchRegister, src2);
- cmpq(src1, kScratchRegister);
- j(overflow, on_not_smi_result, near_jump);
- subq(src1, kScratchRegister);
- } else {
- movq(dst, src1);
- subq(dst, src2);
- j(overflow, on_not_smi_result, near_jump);
- }
+ ASSERT(!src2.AddressUsesRegister(dst));
+ SmiSubHelper<Operand>(this, dst, src1, src2, on_not_smi_result,
near_jump);
}
-void MacroAssembler::SmiSub(Register dst,
- Register src1,
- const Operand& src2) {
+template<class T>
+static void SmiSubNoOverflowHelper(MacroAssembler* masm,
+ Register dst,
+ Register src1,
+ T src2) {
// No overflow checking. Use only when it's known that
// overflowing is impossible (e.g., subtracting two positive smis).
if (!dst.is(src1)) {
- movq(dst, src1);
+ masm->movq(dst, src1);
}
- subq(dst, src2);
- Assert(no_overflow, kSmiSubtractionOverflow);
+ masm->subq(dst, src2);
+ masm->Assert(no_overflow, kSmiSubtractionOverflow);
+}
+
+
+void MacroAssembler::SmiSub(Register dst, Register src1, Register src2) {
+ ASSERT(!dst.is(src2));
+ SmiSubNoOverflowHelper<Register>(this, dst, src1, src2);
+}
+
+
+void MacroAssembler::SmiSub(Register dst,
+ Register src1,
+ const Operand& src2) {
+ SmiSubNoOverflowHelper<Operand>(this, dst, src1, src2);
}
Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index
09dae3e09608b248886bd0a7b47a783a9171d25b..646d7fafc0a575f81ef93f42741512883893de91
100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -596,18 +596,13 @@ class MacroAssembler: public Assembler {
Register src2);
// Subtracts smi values and return the result as a smi.
- // If dst is src1, then src1 will be destroyed, even if
- // the operation is unsuccessful.
+ // If dst is src1, then src1 will be destroyed if the operation is
+ // successful, otherwise kept intact.
void SmiSub(Register dst,
Register src1,
Register src2,
Label* on_not_smi_result,
Label::Distance near_jump = Label::kFar);
-
- void SmiSub(Register dst,
- Register src1,
- Register src2);
-
void SmiSub(Register dst,
Register src1,
const Operand& src2,
@@ -616,6 +611,10 @@ class MacroAssembler: public Assembler {
void SmiSub(Register dst,
Register src1,
+ Register src2);
+
+ void SmiSub(Register dst,
+ Register src1,
const Operand& src2);
// Multiplies smi values and return the result as a smi,
--
--
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