[Reassociation] Fix miscompile for va_arg arguments.

[oota-llvm.git] / test / Transforms / Reassociate / vaarg_movable.ll

diff --git a/test/Transforms/Reassociate/vaarg_movable.ll b/test/Transforms/Reassociate/vaarg_movable.ll
new file mode 100644 (file)
index 0000000..4581bc1
--- /dev/null
+++ b/test/Transforms/Reassociate/vaarg_movable.ll
@@ -0,0 +1,28 @@
+; RUN: opt -S -reassociate -die < %s | FileCheck %s
+
+; The two va_arg instructions depend on the memory/context, are therfore not
+; identical and the sub should not be optimized to 0 by reassociate.
+;
+; CHECK-LABEL @func(
+; ...
+; CHECK: %v0 = va_arg i8** %varargs, i32
+; CHECK: %v1 = va_arg i8** %varargs, i32
+; CHECK: %v0.neg = sub i32 0, %v0
+; CHECK: %sub = add i32 %v0.neg, 1
+; CHECK: %add = add i32 %sub, %v1
+; ...
+; CHECK: ret i32 %add
+define i32 @func(i32 %dummy, ...) {
+  %varargs = alloca i8*, align 8
+  %varargs1 = bitcast i8** %varargs to i8*
+  call void @llvm.va_start(i8* %varargs1)
+  %v0 = va_arg i8** %varargs, i32
+  %v1 = va_arg i8** %varargs, i32
+  %sub = sub nsw i32 %v1, %v0
+  %add = add nsw i32 %sub, 1
+  call void @llvm.va_end(i8* %varargs1)
+  ret i32 %add
+}
+
+declare void @llvm.va_start(i8*)
+declare void @llvm.va_end(i8*)