diff options
| author | Rafael Espindola <rafael.espindola@gmail.com> | 2012-04-04 12:51:34 +0000 |
|---|---|---|
| committer | Rafael Espindola <rafael.espindola@gmail.com> | 2012-04-04 12:51:34 +0000 |
| commit | 26c8dcc692fb2addd475446cfff24d6a4e958bca (patch) | |
| tree | b71cb0d781e2735397c728f276f14ea63780d04c /lib/Transforms/InstCombine/InstCombineAddSub.cpp | |
| parent | 00b73a5e443d49d68f59a5fb517e940842423ae6 (diff) | |
Always compute all the bits in ComputeMaskedBits.
This allows us to keep passing reduced masks to SimplifyDemandedBits, but
know about all the bits if SimplifyDemandedBits fails. This allows instcombine
to simplify cases like the one in the included testcase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154011 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms/InstCombine/InstCombineAddSub.cpp')
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineAddSub.cpp | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp index 908038b35e..05e702fa43 100644 --- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -141,10 +141,9 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { // a sub and fuse this add with it. if (LHS->hasOneUse() && (XorRHS->getValue()+1).isPowerOf2()) { IntegerType *IT = cast<IntegerType>(I.getType()); - APInt Mask = APInt::getAllOnesValue(IT->getBitWidth()); APInt LHSKnownOne(IT->getBitWidth(), 0); APInt LHSKnownZero(IT->getBitWidth(), 0); - ComputeMaskedBits(XorLHS, Mask, LHSKnownZero, LHSKnownOne); + ComputeMaskedBits(XorLHS, LHSKnownZero, LHSKnownOne); if ((XorRHS->getValue() | LHSKnownZero).isAllOnesValue()) return BinaryOperator::CreateSub(ConstantExpr::getAdd(XorRHS, CI), XorLHS); @@ -202,14 +201,13 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { // A+B --> A|B iff A and B have no bits set in common. if (IntegerType *IT = dyn_cast<IntegerType>(I.getType())) { - APInt Mask = APInt::getAllOnesValue(IT->getBitWidth()); APInt LHSKnownOne(IT->getBitWidth(), 0); APInt LHSKnownZero(IT->getBitWidth(), 0); - ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne); + ComputeMaskedBits(LHS, LHSKnownZero, LHSKnownOne); if (LHSKnownZero != 0) { APInt RHSKnownOne(IT->getBitWidth(), 0); APInt RHSKnownZero(IT->getBitWidth(), 0); - ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne); + ComputeMaskedBits(RHS, RHSKnownZero, RHSKnownOne); // No bits in common -> bitwise or. if ((LHSKnownZero|RHSKnownZero).isAllOnesValue()) |