[DeadArgElim] Strip allocsize attributes when deleting an argument.

Since allocsize refers to the argument number it gets invalidated when
an argument is removed and the numbers shift.

llvm-svn: 328481

2 files changed, 19 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp b/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
index 78a2227cde9..3a86c88c98f 100644
--- a/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
+++ b/llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp
@@ -837,10 +837,14 @@ bool DeadArgumentEliminationPass::RemoveDeadStuffFromFunction(Function *F) {
 
   AttributeSet RetAttrs = AttributeSet::get(F->getContext(), RAttrs);
 
+  // Strip allocsize attributes. They might refer to the deleted arguments.
+  AttributeSet FnAttrs = PAL.getFnAttributes().removeAttribute(
+      F->getContext(), Attribute::AllocSize);
+
   // Reconstruct the AttributesList based on the vector we constructed.
   assert(ArgAttrVec.size() == Params.size());
-  AttributeList NewPAL = AttributeList::get(
-      F->getContext(), PAL.getFnAttributes(), RetAttrs, ArgAttrVec);
+  AttributeList NewPAL =
+      AttributeList::get(F->getContext(), FnAttrs, RetAttrs, ArgAttrVec);
 
   // Create the new function type based on the recomputed parameters.
   FunctionType *NFTy = FunctionType::get(NRetTy, Params, FTy->isVarArg());
diff --git a/llvm/test/Transforms/DeadArgElim/allocsize.ll b/llvm/test/Transforms/DeadArgElim/allocsize.ll
new file mode 100644
index 00000000000..eee55f09dc7
--- /dev/null
+++ b/llvm/test/Transforms/DeadArgElim/allocsize.ll
@@ -0,0 +1,13 @@
+; RUN: opt < %s -deadargelim -S | FileCheck %s
+; PR36867
+
+; CHECK-LABEL: @MagickMallocAligned
+; CHECK-NOT: allocsize
+define internal i64 @MagickMallocAligned(i64 %DEADARG1, i64 %s) allocsize(1) {
+        ret i64 %s
+}
+
+define i64 @NeedsArg(i64 %s) {
+	%c = call i64 @MagickMallocAligned(i64 0, i64 %s)
+	ret i64 %c
+}