[v8-dev] Inline inequality compares of strings into CompareICStub. (issue 9649027)

[yangguo]

Reviewers: rossberg,

Message:
PTAL.
Description:
Inline inequality compares of strings into CompareICStub instead of jumping  
into
the CompareStub that handles the generic case.

BUG=
TEST=

Please review this at http://codereview.chromium.org/9649027/

SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge

Affected files:
  M src/ia32/code-stubs-ia32.cc
  M src/ic.cc


Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index  
54a1a348a93f4a1cb306ebeedaf3555ce0c9d93d..d3e2a919cad26ad0d6f3fc36fbec19888be8fee1  
100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -6462,7 +6462,7 @@ void StringCompareStub::GenerateAsciiCharsCompareLoop(
   __ mov_b(scratch, Operand(left, index, times_1, 0));
   __ cmpb(scratch, Operand(right, index, times_1, 0));
   __ j(not_equal, chars_not_equal, chars_not_equal_near);
-  __ add(index, Immediate(1));
+  __ inc(index);
   __ j(not_zero, &loop);
 }

@@ -6645,9 +6645,10 @@ void ICCompareStub::GenerateSymbols(MacroAssembler*  
masm) {

 void ICCompareStub::GenerateStrings(MacroAssembler* masm) {
   ASSERT(state_ == CompareIC::STRINGS);
-  ASSERT(GetCondition() == equal);
   Label miss;

+  bool equality = Token::IsEqualityOp(op_);
+
   // Registers containing left and right operands respectively.
   Register left = edx;
   Register right = eax;
@@ -6686,25 +6687,33 @@ void ICCompareStub::GenerateStrings(MacroAssembler*  
masm) {
   __ bind(&not_same);

   // Check that both strings are symbols. If they are, we're done
-  // because we already know they are not identical.
-  Label do_compare;
-  STATIC_ASSERT(kSymbolTag != 0);
-  __ and_(tmp1, tmp2);
-  __ test(tmp1, Immediate(kIsSymbolMask));
-  __ j(zero, &do_compare, Label::kNear);
-  // Make sure eax is non-zero. At this point input operands are
-  // guaranteed to be non-zero.
-  ASSERT(right.is(eax));
-  __ ret(0);
+  // because we already know they are not identical.  But in the case of
+  // non-equality compare, we still need to determine the order.
+  if (equality) {
+    Label do_compare;
+    STATIC_ASSERT(kSymbolTag != 0);
+    __ and_(tmp1, tmp2);
+    __ test(tmp1, Immediate(kIsSymbolMask));
+    __ j(zero, &do_compare, Label::kNear);
+    // Make sure eax is non-zero. At this point input operands are
+    // guaranteed to be non-zero.
+    ASSERT(right.is(eax));
+    __ ret(0);
+    __ bind(&do_compare);
+  }

   // Check that both strings are sequential ASCII.
   Label runtime;
-  __ bind(&do_compare);
   __ JumpIfNotBothSequentialAsciiStrings(left, right, tmp1, tmp2,  
&runtime);

   // Compare flat ASCII strings. Returns when done.
-  StringCompareStub::GenerateFlatAsciiStringEquals(
-      masm, left, right, tmp1, tmp2);
+  if (equality) {
+    StringCompareStub::GenerateFlatAsciiStringEquals(
+        masm, left, right, tmp1, tmp2);
+  } else {
+    StringCompareStub::GenerateCompareFlatAsciiStrings(
+        masm, left, right, tmp1, tmp2, tmp3);
+  }

   // Handle more complex cases in runtime.
   __ bind(&runtime);
@@ -6712,7 +6721,11 @@ void ICCompareStub::GenerateStrings(MacroAssembler*  
masm) {
   __ push(left);
   __ push(right);
   __ push(tmp1);
-  __ TailCallRuntime(Runtime::kStringEquals, 2, 1);
+  if (equality) {
+    __ TailCallRuntime(Runtime::kStringEquals, 2, 1);
+  } else {
+    __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
+  }

   __ bind(&miss);
   GenerateMiss(masm);
Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index  
88d8a84536c3c08fc3d4d1ea501b9fb00f7968ed..c2ee45ec1e5d6843f40254844b1f82d3994582c1  
100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -2490,9 +2490,13 @@ CompareIC::State CompareIC::TargetState(State state,
           return HEAP_NUMBERS;
         }
       }
-      if (!Token::IsEqualityOp(op_)) return GENERIC;
-      if (x->IsSymbol() && y->IsSymbol()) return SYMBOLS;
+      if (x->IsSymbol() && y->IsSymbol()) {
+        // We compare symbols as strings if we need to determine
+        // the order in a non-equality compare.
+        return Token::IsEqualityOp(op_) ? SYMBOLS : STRINGS;
+      }
       if (x->IsString() && y->IsString()) return STRINGS;
+      if (!Token::IsEqualityOp(op_)) return GENERIC;
       if (x->IsJSObject() && y->IsJSObject()) {
         if (Handle<JSObject>::cast(x)->map() ==
             Handle<JSObject>::cast(y)->map() &&


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