Make SelectionDAG::InferPtrAlignment use llvm::ComputeMaskedBits instead of duplicating the logic for globals. Make llvm::ComputeMaskedBits handle GlobalVariables slightly more aggressively, to match what InferPtrAlignment knew how to do.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145304 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 024a163..aa06955 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -6553,24 +6553,15 @@
const GlobalValue *GV;
int64_t GVOffset = 0;
if (TLI.isGAPlusOffset(Ptr.getNode(), GV, GVOffset)) {
- // If GV has specified alignment, then use it. Otherwise, use the preferred
- // alignment.
- unsigned Align = GV->getAlignment();
- if (!Align) {
- if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
- if (GVar->hasInitializer()) {
- const TargetData *TD = TLI.getTargetData();
- Align = TD->getPreferredAlignment(GVar);
- }
- }
- if (!Align)
- // Conservatively returns zero here instead of using ABI alignment for
- // type of the GV. If the type is a "packed" type, then the under-
- // specified alignments is attached to the load / store instructions.
- // In that case, the alignment of the type cannot be trusted.
- return 0;
- }
- return MinAlign(Align, GVOffset);
+ unsigned PtrWidth = TLI.getPointerTy().getSizeInBits();
+ APInt AllOnes = APInt::getAllOnesValue(PtrWidth);
+ APInt KnownZero(PtrWidth, 0), KnownOne(PtrWidth, 0);
+ llvm::ComputeMaskedBits(const_cast<GlobalValue*>(GV), AllOnes,
+ KnownZero, KnownOne, TLI.getTargetData());
+ unsigned AlignBits = KnownZero.countTrailingOnes();
+ unsigned Align = AlignBits ? 1 << std::min(31U, AlignBits) : 0;
+ if (Align)
+ return MinAlign(Align, GVOffset);
}
// If this is a direct reference to a stack slot, use information about the