[ExpandMemCmp] Correctly set alignment of generated loads
Summary:
This is a part of the series of efforts for correcting alignment of memory operations.
(Another related bugs: https://bugs.llvm.org/show_bug.cgi?id=44388 , https://bugs.llvm.org/show_bug.cgi?id=44543 )
This fixes https://bugs.llvm.org/show_bug.cgi?id=43880 by giving default alignment of loads to 1.
The test CodeGen/AArch64/bcmp-inline-small.ll should have been changed; it was introduced by https://reviews.llvm.org/D64805 . I talked with @evandro, and confirmed that the test is okay to be changed.
Other two tests from PowerPC needed changes as well, but fixes were straightforward.
Reviewers: courbet
Reviewed By: courbet
Subscribers: nlopes, gchatelet, wuzish, nemanjai, kristof.beyls, hiraditya, steven.zhang, danielkiss, llvm-commits, evandro
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76113
diff --git a/llvm/lib/CodeGen/ExpandMemCmp.cpp b/llvm/lib/CodeGen/ExpandMemCmp.cpp
index 213416d..7cf3f08 100644
--- a/llvm/lib/CodeGen/ExpandMemCmp.cpp
+++ b/llvm/lib/CodeGen/ExpandMemCmp.cpp
@@ -273,6 +273,8 @@
// Get the memory source at offset `OffsetBytes`.
Value *LhsSource = CI->getArgOperand(0);
Value *RhsSource = CI->getArgOperand(1);
+ Align LhsAlign = LhsSource->getPointerAlignment(DL).valueOrOne();
+ Align RhsAlign = RhsSource->getPointerAlignment(DL).valueOrOne();
if (OffsetBytes > 0) {
auto *ByteType = Type::getInt8Ty(CI->getContext());
LhsSource = Builder.CreateConstGEP1_64(
@@ -281,6 +283,8 @@
RhsSource = Builder.CreateConstGEP1_64(
ByteType, Builder.CreateBitCast(RhsSource, ByteType->getPointerTo()),
OffsetBytes);
+ LhsAlign = commonAlignment(LhsAlign, OffsetBytes);
+ RhsAlign = commonAlignment(RhsAlign, OffsetBytes);
}
LhsSource = Builder.CreateBitCast(LhsSource, LoadSizeType->getPointerTo());
RhsSource = Builder.CreateBitCast(RhsSource, LoadSizeType->getPointerTo());
@@ -290,13 +294,13 @@
if (auto *C = dyn_cast<Constant>(LhsSource))
Lhs = ConstantFoldLoadFromConstPtr(C, LoadSizeType, DL);
if (!Lhs)
- Lhs = Builder.CreateLoad(LoadSizeType, LhsSource);
+ Lhs = Builder.CreateAlignedLoad(LoadSizeType, LhsSource, LhsAlign);
Value *Rhs = nullptr;
if (auto *C = dyn_cast<Constant>(RhsSource))
Rhs = ConstantFoldLoadFromConstPtr(C, LoadSizeType, DL);
if (!Rhs)
- Rhs = Builder.CreateLoad(LoadSizeType, RhsSource);
+ Rhs = Builder.CreateAlignedLoad(LoadSizeType, RhsSource, RhsAlign);
// Swap bytes if required.
if (NeedsBSwap) {