Changes in directory llvm/lib/Transforms/Scalar:
InstructionCombining.cpp updated: 1.431 -> 1.432
---
Log message:
remove some more dead special case code
---
Diffs of the changes: (+8 -35)
InstructionCombining.cpp | 43 ++++++++-----------------------------------
1 files changed, 8 insertions(+), 35 deletions(-)
Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.431
llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.432
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.431 Sun Feb 12
02:02:11 2006
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp Sun Feb 12 02:07:37 2006
@@ -3940,7 +3940,7 @@
if (Op1 == Constant::getNullValue(Type::UByteTy) ||
Op0 == Constant::getNullValue(Op0->getType()))
return ReplaceInstUsesWith(I, Op0);
-
+
if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
if (!isLeftShift && I.getType()->isSigned())
return ReplaceInstUsesWith(I, Op0);
@@ -3989,6 +3989,13 @@
bool isSignedShift = Op0->getType()->isSigned();
bool isUnsignedShift = !isSignedShift;
+ // See if we can simplify any instructions used by the instruction whose
sole
+ // purpose is to compute bits we don't care about.
+ uint64_t KnownZero, KnownOne;
+ if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(),
+ KnownZero, KnownOne))
+ return &I;
+
// shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
// of a signed value.
//
@@ -4018,40 +4025,6 @@
return NV;
if (Op0->hasOneUse()) {
- // If this is a SHL of a sign-extending cast, see if we can turn the input
- // into a zero extending cast (a simple strength reduction).
- if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
- const Type *SrcTy = CI->getOperand(0)->getType();
- if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
- SrcTy->getPrimitiveSizeInBits() <
- CI->getType()->getPrimitiveSizeInBits()) {
- // We can change it to a zero extension if we are shifting out all of
- // the sign extended bits. To check this, form a mask of all of the
- // sign extend bits, then shift them left and see if we have anything
- // left.
- Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
- Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
- Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
- if (ConstantExpr::getShl(Mask, Op1)->isNullValue()) {
- // If the shift is nuking all of the sign bits, change this to a
- // zero extension cast. To do this, cast the cast input to
- // unsigned, then to the requested size.
- Value *CastOp = CI->getOperand(0);
- Instruction *NC =
- new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
- CI->getName()+".uns");
- NC = InsertNewInstBefore(NC, I);
- // Finally, insert a replacement for CI.
- NC = new CastInst(NC, CI->getType(), CI->getName());
- CI->setName("");
- NC = InsertNewInstBefore(NC, I);
- WorkList.push_back(CI); // Delete CI later.
- I.setOperand(0, NC);
- return &I; // The SHL operand was modified.
- }
- }
- }
-
if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
// Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
Value *V1, *V2;
_______________________________________________
llvm-commits mailing list
llvm-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
