[PATCH] D115888: [Attributor][Fix] Add default alignment to HeapToStack

[Joseph Huber via Phabricator via llvm-commits]

jhuber6 created this revision.
jhuber6 added reviewers: jdoerfert, tianshilei1992.
Herald added subscribers: ormris, okura, kuter, uenoku, hiraditya.
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This patch adds the default alignment of `16` to the alloca instruction
replacing a dynamic memory allocation. Clang typically assumed `malloc`
will return an address aligned to a 16 byte boundary, so we copy that
assumption here when we replace a memory allocation instruction. This
previously caused errors in cases where the replaced alloca had a
smaller alignment than would have been provided by the malloc call.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D115888

Files:
  llvm/lib/Transforms/IPO/AttributorAttributes.cpp


Index: llvm/lib/Transforms/IPO/AttributorAttributes.cpp
===================================================================
--- llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -5928,7 +5928,7 @@
         Size = AI.CB->getOperand(0);
       }
 
-      Align Alignment(1);
+      Align Alignment(16);
       if (AI.Kind == AllocationInfo::AllocationKind::ALIGNED_ALLOC) {
         Optional<APInt> AlignmentAPI =
             getAPInt(A, *this, *AI.CB->getArgOperand(0));


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