Changes in directory llvm/lib/Analysis:
ScalarEvolution.cpp updated: 1.105 -> 1.106
---
Log message:
Treat xor of signbit like an add.
---
Diffs of the changes: (+10 -1)
ScalarEvolution.cpp | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletion(-)
Index: llvm/lib/Analysis/ScalarEvolution.cpp
diff -u llvm/lib/Analysis/ScalarEvolution.cpp:1.105
llvm/lib/Analysis/ScalarEvolution.cpp:1.106
--- llvm/lib/Analysis/ScalarEvolution.cpp:1.105 Sat Mar 3 19:25:35 2007
+++ llvm/lib/Analysis/ScalarEvolution.cpp Mon Apr 2 00:41:38 2007
@@ -1427,7 +1427,16 @@
}
}
break;
-
+ case Instruction::Xor:
+ // If the RHS of the xor is a signbit, then this is just an add.
+ // Instcombine turns add of signbit into xor as a strength reduction
step.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ if (CI->getValue().isSignBit())
+ return SCEVAddExpr::get(getSCEV(I->getOperand(0)),
+ getSCEV(I->getOperand(1)));
+ }
+ break;
+
case Instruction::Shl:
// Turn shift left of a constant amount into a multiply.
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
_______________________________________________
llvm-commits mailing list
llvm-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
