ABI handling: Fix nasty thinko where IRgen could generate an out-of-bounds read
when generating a coercion for ABI handling purposes.
- This may only manifest itself when building at -O0, but the practical effect
is that other arguments may get clobbered.
- <rdar://problem/6930451> [irgen] ABI coercion clobbers other arguments
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72932 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 954ac53..248619f 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -1638,13 +1638,7 @@
uint64_t DstSize = CGF.CGM.getTargetData().getTypeAllocSize(DstTy);
// If store is legal, just bitcast the src pointer.
- if (SrcSize >= DstSize) {
- // Generally SrcSize is never greater than DstSize, since this means we are
- // losing bits. However, this can happen in cases where the structure has
- // additional padding, for example due to a user specified alignment.
- //
- // FIXME: Assert that we aren't truncating non-padding bits when have access
- // to that information.
+ if (SrcSize <= DstSize) {
llvm::Value *Casted =
CGF.Builder.CreateBitCast(DstPtr, llvm::PointerType::getUnqual(SrcTy));
// FIXME: Use better alignment / avoid requiring aligned store.
@@ -1652,6 +1646,13 @@
} else {
// Otherwise do coercion through memory. This is stupid, but
// simple.
+
+ // Generally SrcSize is never greater than DstSize, since this means we are
+ // losing bits. However, this can happen in cases where the structure has
+ // additional padding, for example due to a user specified alignment.
+ //
+ // FIXME: Assert that we aren't truncating non-padding bits when have access
+ // to that information.
llvm::Value *Tmp = CGF.CreateTempAlloca(SrcTy);
CGF.Builder.CreateStore(Src, Tmp);
llvm::Value *Casted =