Author: jyknight
Date: Tue Dec 29 21:58:33 2015
New Revision: 256619
URL: http://llvm.org/viewvc/llvm-project?rev=256619&view=rev
Log:
Fix alignment issue in CodeGenFunction::PopCleanupBlock.
It was copying an EHCleanupStack::Cleanup object into a
SmallVector<char>, with a comment saying that SmallVector's alignment is
always large enough. Unfortunately, that isn't actually true after
r162331 in 2012.
Expand the code (somewhat distastefully) to get a stack allocation with
a correct alignment.
Modified:
cfe/trunk/lib/CodeGen/CGCleanup.cpp
Modified: cfe/trunk/lib/CodeGen/CGCleanup.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCleanup.cpp?rev=256619&r1=256618&r2=256619&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGCleanup.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGCleanup.cpp Tue Dec 29 21:58:33 2015
@@ -676,13 +676,25 @@ void CodeGenFunction::PopCleanupBlock(bo
return;
}
- // Copy the cleanup emission data out. Note that SmallVector
- // guarantees maximal alignment for its buffer regardless of its
- // type parameter.
+ // Copy the cleanup emission data out. This uses either a stack
+ // array or malloc'd memory, depending on the size, which is
+ // behavior that SmallVector would provide, if we could use it
+ // here. Unfortunately, if you ask for a SmallVector<char>, the
+ // alignment isn't sufficient.
auto *CleanupSource = reinterpret_cast<char *>(Scope.getCleanupBuffer());
- SmallVector<char, 8 * sizeof(void *)> CleanupBuffer(
- CleanupSource, CleanupSource + Scope.getCleanupSize());
- auto *Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBuffer.data());
+ llvm::AlignedCharArray<EHScopeStack::ScopeStackAlignment, 8 * sizeof(void
*)> CleanupBufferStack;
+ std::unique_ptr<char[]> CleanupBufferHeap;
+ size_t CleanupSize = Scope.getCleanupSize();
+ EHScopeStack::Cleanup *Fn;
+
+ if (CleanupSize <= sizeof(CleanupBufferStack)) {
+ memcpy(CleanupBufferStack.buffer, CleanupSource, CleanupSize);
+ Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferStack.buffer);
+ } else {
+ CleanupBufferHeap.reset(new char[CleanupSize]);
+ memcpy(CleanupBufferHeap.get(), CleanupSource, CleanupSize);
+ Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferHeap.get());
+ }
EHScopeStack::Cleanup::Flags cleanupFlags;
if (Scope.isNormalCleanup())
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