Revision: 7809
Author: [email protected]
Date: Fri May 6 07:19:51 2011
Log: Extract common code in string compare loops.
Review URL: http://codereview.chromium.org/6927044
http://code.google.com/p/v8/source/detail?r=7809
Modified:
/branches/bleeding_edge/src/arm/code-stubs-arm.cc
/branches/bleeding_edge/src/arm/code-stubs-arm.h
/branches/bleeding_edge/src/ia32/code-stubs-ia32.cc
/branches/bleeding_edge/src/ia32/code-stubs-ia32.h
/branches/bleeding_edge/src/x64/code-stubs-x64.cc
/branches/bleeding_edge/src/x64/code-stubs-x64.h
=======================================
--- /branches/bleeding_edge/src/arm/code-stubs-arm.cc Thu May 5 05:30:57
2011
+++ /branches/bleeding_edge/src/arm/code-stubs-arm.cc Fri May 6 07:19:51
2011
@@ -5430,27 +5430,9 @@
// Compare characters.
__ bind(&compare_chars);
-
- // Change index to run from -length to -1 by adding length to string
- // start. This means that loop ends when index reaches zero, which
- // doesn't need an additional compare.
- __ SmiUntag(length);
- __ add(scratch2, length,
- Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
- __ add(left, left, Operand(scratch2));
- __ add(right, right, Operand(scratch2));
- __ rsb(length, length, Operand(0));
- Register index = length; // index = -length;
-
- // Compare loop.
- Label loop;
- __ bind(&loop);
- __ ldrb(scratch2, MemOperand(left, index));
- __ ldrb(scratch3, MemOperand(right, index));
- __ cmp(scratch2, scratch3);
- __ b(ne, &strings_not_equal);
- __ add(index, index, Operand(1), SetCC);
- __ b(ne, &loop);
+ GenerateAsciiCharsCompareLoop(masm,
+ left, right, length, scratch2, scratch3,
+ &strings_not_equal);
// Characters are equal.
__ mov(r0, Operand(Smi::FromInt(EQUAL)));
@@ -5465,7 +5447,7 @@
Register scratch2,
Register scratch3,
Register scratch4)
{
- Label compare_lengths;
+ Label result_not_equal, compare_lengths;
// Find minimum length and length difference.
__ ldr(scratch1, FieldMemOperand(left, String::kLengthOffset));
__ ldr(scratch2, FieldMemOperand(right, String::kLengthOffset));
@@ -5477,44 +5459,54 @@
__ tst(min_length, Operand(min_length));
__ b(eq, &compare_lengths);
- // Untag smi.
- __ mov(min_length, Operand(min_length, ASR, kSmiTagSize));
-
- // Setup registers so that we only need to increment one register
- // in the loop.
- __ add(scratch2, min_length,
- Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
- __ add(left, left, Operand(scratch2));
- __ add(right, right, Operand(scratch2));
- // Registers left and right points to the min_length character of
strings.
- __ rsb(min_length, min_length, Operand(-1));
- Register index = min_length;
- // Index starts at -min_length.
-
- {
- // Compare loop.
- Label loop;
- __ bind(&loop);
- // Compare characters.
- __ add(index, index, Operand(1), SetCC);
- __ ldrb(scratch2, MemOperand(left, index), ne);
- __ ldrb(scratch4, MemOperand(right, index), ne);
- // Skip to compare lengths with eq condition true.
- __ b(eq, &compare_lengths);
- __ cmp(scratch2, scratch4);
- __ b(eq, &loop);
- // Fallthrough with eq condition false.
- }
- // Compare lengths - strings up to min-length are equal.
+ // Compare loop.
+ GenerateAsciiCharsCompareLoop(masm,
+ left, right, min_length, scratch2,
scratch4,
+ &result_not_equal);
+
+ // Compare lengths - strings up to min-length are equal.
__ bind(&compare_lengths);
ASSERT(Smi::FromInt(EQUAL) == static_cast<Smi*>(0));
- // Use zero length_delta as result.
- __ mov(r0, Operand(length_delta), SetCC, eq);
- // Fall through to here if characters compare not-equal.
+ // Use length_delta as result if it's zero.
+ __ mov(r0, Operand(length_delta), SetCC);
+ __ bind(&result_not_equal);
+ // Conditionally update the result based either on length_delta or
+ // the last comparion performed in the loop above.
__ mov(r0, Operand(Smi::FromInt(GREATER)), LeaveCC, gt);
__ mov(r0, Operand(Smi::FromInt(LESS)), LeaveCC, lt);
__ Ret();
}
+
+
+void StringCompareStub::GenerateAsciiCharsCompareLoop(
+ MacroAssembler* masm,
+ Register left,
+ Register right,
+ Register length,
+ Register scratch1,
+ Register scratch2,
+ Label* chars_not_equal) {
+ // Change index to run from -length to -1 by adding length to string
+ // start. This means that loop ends when index reaches zero, which
+ // doesn't need an additional compare.
+ __ SmiUntag(length);
+ __ add(scratch1, length,
+ Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+ __ add(left, left, Operand(scratch1));
+ __ add(right, right, Operand(scratch1));
+ __ rsb(length, length, Operand(0));
+ Register index = length; // index = -length;
+
+ // Compare loop.
+ Label loop;
+ __ bind(&loop);
+ __ ldrb(scratch1, MemOperand(left, index));
+ __ ldrb(scratch2, MemOperand(right, index));
+ __ cmp(scratch1, scratch2);
+ __ b(ne, chars_not_equal);
+ __ add(index, index, Operand(1), SetCC);
+ __ b(ne, &loop);
+}
void StringCompareStub::Generate(MacroAssembler* masm) {
=======================================
--- /branches/bleeding_edge/src/arm/code-stubs-arm.h Thu May 5 05:30:57
2011
+++ /branches/bleeding_edge/src/arm/code-stubs-arm.h Fri May 6 07:19:51
2011
@@ -346,10 +346,17 @@
Register scratch3);
private:
- Major MajorKey() { return StringCompare; }
- int MinorKey() { return 0; }
-
- void Generate(MacroAssembler* masm);
+ virtual Major MajorKey() { return StringCompare; }
+ virtual int MinorKey() { return 0; }
+ virtual void Generate(MacroAssembler* masm);
+
+ static void GenerateAsciiCharsCompareLoop(MacroAssembler* masm,
+ Register left,
+ Register right,
+ Register length,
+ Register scratch1,
+ Register scratch2,
+ Label* chars_not_equal);
};
=======================================
--- /branches/bleeding_edge/src/ia32/code-stubs-ia32.cc Thu May 5 05:30:57
2011
+++ /branches/bleeding_edge/src/ia32/code-stubs-ia32.cc Fri May 6 07:19:51
2011
@@ -5637,26 +5637,8 @@
// Compare characters.
__ bind(&compare_chars);
-
- // Change index to run from -length to -1 by adding length to string
- // start. This means that loop ends when index reaches zero, which
- // doesn't need an additional compare.
- __ SmiUntag(length);
- __ lea(left,
- FieldOperand(left, length, times_1, SeqAsciiString::kHeaderSize));
- __ lea(right,
- FieldOperand(right, length, times_1,
SeqAsciiString::kHeaderSize));
- __ neg(length);
- Register index = length; // index = -length;
-
- // Compare loop.
- NearLabel loop;
- __ bind(&loop);
- __ mov_b(scratch2, Operand(left, index, times_1, 0));
- __ cmpb(scratch2, Operand(right, index, times_1, 0));
- __ j(not_equal, &strings_not_equal);
- __ add(Operand(index), Immediate(1));
- __ j(not_zero, &loop);
+ GenerateAsciiCharsCompareLoop(masm, left, right, length, scratch2,
+ &strings_not_equal);
// Characters are equal.
__ Set(eax, Immediate(Smi::FromInt(EQUAL)));
@@ -5670,10 +5652,6 @@
Register scratch1,
Register scratch2,
Register scratch3)
{
- Label result_not_equal;
- Label result_greater;
- Label compare_lengths;
-
Counters* counters = masm->isolate()->counters();
__ IncrementCounter(counters->string_compare_native(), 1);
@@ -5693,36 +5671,14 @@
Register min_length = scratch1;
// If either length is zero, just compare lengths.
+ NearLabel compare_lengths;
__ test(min_length, Operand(min_length));
__ j(zero, &compare_lengths);
- // Change index to run from -min_length to -1 by adding min_length
- // to string start. This means that loop ends when index reaches zero,
- // which doesn't need an additional compare.
- __ SmiUntag(min_length);
- __ lea(left,
- FieldOperand(left,
- min_length, times_1,
- SeqAsciiString::kHeaderSize));
- __ lea(right,
- FieldOperand(right,
- min_length, times_1,
- SeqAsciiString::kHeaderSize));
- __ neg(min_length);
-
- Register index = min_length; // index = -min_length;
-
- {
- // Compare loop.
- NearLabel loop;
- __ bind(&loop);
- // Compare characters.
- __ mov_b(scratch2, Operand(left, index, times_1, 0));
- __ cmpb(scratch2, Operand(right, index, times_1, 0));
- __ j(not_equal, &result_not_equal);
- __ add(Operand(index), Immediate(1));
- __ j(not_zero, &loop);
- }
+ // Compare characters.
+ NearLabel result_not_equal;
+ GenerateAsciiCharsCompareLoop(masm, left, right, min_length, scratch2,
+ &result_not_equal);
// Compare lengths - strings up to min-length are equal.
__ bind(&compare_lengths);
@@ -5735,6 +5691,7 @@
__ Set(eax, Immediate(Smi::FromInt(EQUAL)));
__ ret(0);
+ NearLabel result_greater;
__ bind(&result_not_equal);
__ j(greater, &result_greater);
@@ -5747,6 +5704,35 @@
__ Set(eax, Immediate(Smi::FromInt(GREATER)));
__ ret(0);
}
+
+
+void StringCompareStub::GenerateAsciiCharsCompareLoop(
+ MacroAssembler* masm,
+ Register left,
+ Register right,
+ Register length,
+ Register scratch,
+ NearLabel* chars_not_equal) {
+ // Change index to run from -length to -1 by adding length to string
+ // start. This means that loop ends when index reaches zero, which
+ // doesn't need an additional compare.
+ __ SmiUntag(length);
+ __ lea(left,
+ FieldOperand(left, length, times_1, SeqAsciiString::kHeaderSize));
+ __ lea(right,
+ FieldOperand(right, length, times_1,
SeqAsciiString::kHeaderSize));
+ __ neg(length);
+ Register index = length; // index = -length;
+
+ // Compare loop.
+ NearLabel loop;
+ __ bind(&loop);
+ __ mov_b(scratch, Operand(left, index, times_1, 0));
+ __ cmpb(scratch, Operand(right, index, times_1, 0));
+ __ j(not_equal, chars_not_equal);
+ __ add(Operand(index), Immediate(1));
+ __ j(not_zero, &loop);
+}
void StringCompareStub::Generate(MacroAssembler* masm) {
=======================================
--- /branches/bleeding_edge/src/ia32/code-stubs-ia32.h Thu May 5 05:30:57
2011
+++ /branches/bleeding_edge/src/ia32/code-stubs-ia32.h Fri May 6 07:19:51
2011
@@ -391,10 +391,16 @@
Register scratch2);
private:
- Major MajorKey() { return StringCompare; }
- int MinorKey() { return 0; }
-
- void Generate(MacroAssembler* masm);
+ virtual Major MajorKey() { return StringCompare; }
+ virtual int MinorKey() { return 0; }
+ virtual void Generate(MacroAssembler* masm);
+
+ static void GenerateAsciiCharsCompareLoop(MacroAssembler* masm,
+ Register left,
+ Register right,
+ Register length,
+ Register scratch,
+ NearLabel* chars_not_equal);
};
=======================================
--- /branches/bleeding_edge/src/x64/code-stubs-x64.cc Thu May 5 05:30:57
2011
+++ /branches/bleeding_edge/src/x64/code-stubs-x64.cc Fri May 6 07:19:51
2011
@@ -4523,26 +4523,9 @@
// Compare characters.
__ bind(&compare_chars);
-
- // Change index to run from -length to -1 by adding length to string
- // start. This means that loop ends when index reaches zero, which
- // doesn't need an additional compare.
- __ SmiToInteger32(length, length);
- __ lea(left,
- FieldOperand(left, length, times_1, SeqAsciiString::kHeaderSize));
- __ lea(right,
- FieldOperand(right, length, times_1,
SeqAsciiString::kHeaderSize));
- __ neg(length);
- Register index = length; // index = -length;
-
- // Compare loop.
- NearLabel strings_not_equal, loop;
- __ bind(&loop);
- __ movb(scratch2, Operand(left, index, times_1, 0));
- __ cmpb(scratch2, Operand(right, index, times_1, 0));
- __ j(not_equal, &strings_not_equal);
- __ addq(index, Immediate(1));
- __ j(not_zero, &loop);
+ NearLabel strings_not_equal;
+ GenerateAsciiCharsCompareLoop(masm, left, right, length, scratch2,
+ &strings_not_equal);
// Characters are equal.
__ Move(rax, Smi::FromInt(EQUAL));
@@ -4589,35 +4572,11 @@
__ SmiTest(min_length);
__ j(zero, &compare_lengths);
- __ SmiToInteger32(min_length, min_length);
-
- // Registers scratch2 and scratch3 are free.
+ // Compare loop.
NearLabel result_not_equal;
- Label loop;
- {
- // Check characters 0 .. min_length - 1 in a loop.
- // Use scratch3 as loop index, min_length as limit and scratch2
- // for computation.
- const Register index = scratch3;
- __ Set(index, 0); // Index into strings.
- __ bind(&loop);
- // Compare characters.
- // TODO(lrn): Could we load more than one character at a time?
- __ movb(scratch2, FieldOperand(left,
- index,
- times_1,
- SeqAsciiString::kHeaderSize));
- // Increment index and use -1 modifier on next load to give
- // the previous load extra time to complete.
- __ addl(index, Immediate(1));
- __ cmpb(scratch2, FieldOperand(right,
- index,
- times_1,
- SeqAsciiString::kHeaderSize - 1));
- __ j(not_equal, &result_not_equal);
- __ cmpl(index, min_length);
- __ j(not_equal, &loop);
- }
+ GenerateAsciiCharsCompareLoop(masm, left, right, min_length, scratch2,
+ &result_not_equal);
+
// Completed loop without finding different characters.
// Compare lengths (precomputed).
__ bind(&compare_lengths);
@@ -4642,6 +4601,35 @@
__ Move(rax, Smi::FromInt(GREATER));
__ ret(0);
}
+
+
+void StringCompareStub::GenerateAsciiCharsCompareLoop(
+ MacroAssembler* masm,
+ Register left,
+ Register right,
+ Register length,
+ Register scratch,
+ NearLabel* chars_not_equal) {
+ // Change index to run from -length to -1 by adding length to string
+ // start. This means that loop ends when index reaches zero, which
+ // doesn't need an additional compare.
+ __ SmiToInteger32(length, length);
+ __ lea(left,
+ FieldOperand(left, length, times_1, SeqAsciiString::kHeaderSize));
+ __ lea(right,
+ FieldOperand(right, length, times_1,
SeqAsciiString::kHeaderSize));
+ __ neg(length);
+ Register index = length; // index = -length;
+
+ // Compare loop.
+ NearLabel loop;
+ __ bind(&loop);
+ __ movb(scratch, Operand(left, index, times_1, 0));
+ __ cmpb(scratch, Operand(right, index, times_1, 0));
+ __ j(not_equal, chars_not_equal);
+ __ addq(index, Immediate(1));
+ __ j(not_zero, &loop);
+}
void StringCompareStub::Generate(MacroAssembler* masm) {
=======================================
--- /branches/bleeding_edge/src/x64/code-stubs-x64.h Thu May 5 05:30:57
2011
+++ /branches/bleeding_edge/src/x64/code-stubs-x64.h Fri May 6 07:19:51
2011
@@ -384,10 +384,16 @@
Register scratch2);
private:
- Major MajorKey() { return StringCompare; }
- int MinorKey() { return 0; }
-
- void Generate(MacroAssembler* masm);
+ virtual Major MajorKey() { return StringCompare; }
+ virtual int MinorKey() { return 0; }
+ virtual void Generate(MacroAssembler* masm);
+
+ static void GenerateAsciiCharsCompareLoop(MacroAssembler* masm,
+ Register left,
+ Register right,
+ Register length,
+ Register scratch,
+ NearLabel* chars_not_equal);
};
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