Author: [email protected]
Date: Wed Mar 4 00:50:38 2009
New Revision: 1410
Modified:
branches/bleeding_edge/src/codegen-ia32.cc
Log:
Streamline CodeGenerator::Comparison in the IA32 code generator. When
doing constant folding, handle only the cases that actually arise.
This avoids some complicated logic, some extra comparisons, and fixes
issue 247:
http://code.google.com/p/v8/issues/detail?id=247
Review URL: http://codereview.chromium.org/40023
Modified: branches/bleeding_edge/src/codegen-ia32.cc
==============================================================================
--- branches/bleeding_edge/src/codegen-ia32.cc (original)
+++ branches/bleeding_edge/src/codegen-ia32.cc Wed Mar 4 00:50:38 2009
@@ -1306,6 +1306,8 @@
right_side = frame_->Pop();
left_side = frame_->Pop();
}
+ ASSERT(cc == less || cc == equal || cc == greater_equal);
+
// If either side is a constant smi, optimize the comparison.
bool left_side_constant_smi =
left_side.is_constant() && left_side.handle()->IsSmi();
@@ -1321,17 +1323,18 @@
// Trivial case, comparing two constants.
int left_value = Smi::cast(*left_side.handle())->value();
int right_value = Smi::cast(*right_side.handle())->value();
- if (left_value < right_value &&
- (cc == less || cc == less_equal || cc == not_equal) ||
- left_value == right_value &&
- (cc == less_equal || cc == equal || cc == greater_equal) ||
- left_value > right_value &&
- (cc == greater || cc == greater_equal || cc == not_equal)) {
- // The comparison is unconditionally true.
- dest->Goto(true);
- } else {
- // The comparison is unconditionally false.
- dest->Goto(false);
+ switch (cc) {
+ case less:
+ dest->Goto(left_value < right_value);
+ break;
+ case equal:
+ dest->Goto(left_value == right_value);
+ break;
+ case greater_equal:
+ dest->Goto(left_value >= right_value);
+ break;
+ default:
+ UNREACHABLE();
}
} else { // Only one side is a constant Smi.
// If left side is a constant Smi, reverse the operands.
@@ -1417,8 +1420,8 @@
} else { // Neither side is a constant Smi or null.
// If either side is a non-smi constant, skip the smi check.
bool known_non_smi =
- left_side.is_constant() && !left_side.handle()->IsSmi() ||
- right_side.is_constant() && !right_side.handle()->IsSmi();
+ (left_side.is_constant() && !left_side.handle()->IsSmi()) ||
+ (right_side.is_constant() && !right_side.handle()->IsSmi());
left_side.ToRegister();
right_side.ToRegister();
JumpTarget is_smi(this);
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