testcase for PR3381.

Also it was an empty struct, not a void after all.

llvm-svn: 62920

2 files changed, 19 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
index aed08670932..40289eaf6bf 100644
--- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -11170,7 +11170,7 @@ static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
     
     while (1) {
       if (const StructType *STy = dyn_cast<StructType>(SrcPTy)) {
-        if (!STy->getNumElements()) /* Void is represented as {} */
+        if (!STy->getNumElements()) /* Struct can be empty {} */
           break;
         NewGEPIndices.push_back(Zero);
         SrcPTy = STy->getElementType(0);
diff --git a/llvm/test/Transforms/InstCombine/2009-01-24-EmptyStruct.ll b/llvm/test/Transforms/InstCombine/2009-01-24-EmptyStruct.ll
new file mode 100644
index 00000000000..313e76d028d
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/2009-01-24-EmptyStruct.ll
@@ -0,0 +1,18 @@
+; RUN: llvm-as < %s | opt -instcombine
+; PR3381
+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"
+target triple = "x86_64-unknown-linux-gnu"
+	%struct.atomic_t = type { i32 }
+	%struct.inode = type { i32, %struct.mutex }
+	%struct.list_head = type { %struct.list_head*, %struct.list_head* }
+	%struct.lock_class_key = type {  }
+	%struct.mutex = type { %struct.atomic_t, %struct.rwlock_t, %struct.list_head }
+	%struct.rwlock_t = type { %struct.lock_class_key }
+
+define void @handle_event(%struct.inode* %bar) nounwind {
+entry:
+	%0 = getelementptr %struct.inode* %bar, i64 -1, i32 1, i32 1		; <%struct.rwlock_t*> [#uses=1]
+	%1 = bitcast %struct.rwlock_t* %0 to i32*		; <i32*> [#uses=1]
+	store i32 1, i32* %1, align 4
+	ret void
+}