diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp | 10 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/2012-09-17-ZeroSizedAlloca.ll | 24 |
2 files changed, 31 insertions, 3 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp index 6ecb4c52c4..5b6cf4a4a8 100644 --- a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp +++ b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp @@ -246,12 +246,16 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) { return &AI; } + // If the alignment of the entry block alloca is 0 (unspecified), + // assign it the preferred alignment. + if (EntryAI->getAlignment() == 0) + EntryAI->setAlignment( + TD->getPrefTypeAlignment(EntryAI->getAllocatedType())); // Replace this zero-sized alloca with the one at the start of the entry // block after ensuring that the address will be aligned enough for both // types. - unsigned MaxAlign = - std::max(TD->getPrefTypeAlignment(EntryAI->getAllocatedType()), - TD->getPrefTypeAlignment(AI.getAllocatedType())); + unsigned MaxAlign = std::max(EntryAI->getAlignment(), + AI.getAlignment()); EntryAI->setAlignment(MaxAlign); if (AI.getType() != EntryAI->getType()) return new BitCastInst(EntryAI, AI.getType()); diff --git a/test/Transforms/InstCombine/2012-09-17-ZeroSizedAlloca.ll b/test/Transforms/InstCombine/2012-09-17-ZeroSizedAlloca.ll new file mode 100644 index 0000000000..ba025e92b0 --- /dev/null +++ b/test/Transforms/InstCombine/2012-09-17-ZeroSizedAlloca.ll @@ -0,0 +1,24 @@ +; RUN: opt -S -instcombine < %s | FileCheck %s + +; When merging zero sized alloca check that requested alignments of the allocas +; are obeyed. + +@x = global i8* null, align 8 +@y = global i8* null, align 8 + +target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128" +target triple = "x86_64-apple-macosx10.8.0" + +; CHECK: @f +; CHECK-NEXT: alloca [0 x i8], align 1024 +; CHECK-NOT: alloca +; CHECK: ret void +define void @f() { + %1 = alloca [0 x i8], align 1 + %2 = alloca [0 x i8], align 1024 + %3 = getelementptr inbounds [0 x i8]* %1, i64 0, i64 0 + %4 = getelementptr inbounds [0 x i8]* %2, i64 0, i64 0 + store i8* %3, i8** @x, align 8 + store i8* %4, i8** @y, align 8 + ret void +} |