[InstCombine] Don't DSE across readnone functions that may throw
Summary: Depends on D28740
Reviewers: dberlin, chandlerc, hfinkel, majnemer
Subscribers: mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D28742
llvm-svn: 292197
diff --git a/llvm/test/Transforms/InstCombine/readnone-maythrow.ll b/llvm/test/Transforms/InstCombine/readnone-maythrow.ll
new file mode 100644
index 0000000..f01e902
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/readnone-maythrow.ll
@@ -0,0 +1,34 @@
+; RUN: opt -S -instcombine < %s | FileCheck %s
+
+declare void @readnone_but_may_throw() readnone
+
+define void @f_0(i32* %ptr) {
+; CHECK-LABEL: @f_0(
+entry:
+; CHECK: store i32 10, i32* %ptr
+; CHECK-NEXT: call void @readnone_but_may_throw()
+; CHECK-NEXT: store i32 20, i32* %ptr, align 4
+; CHECK: ret void
+
+ store i32 10, i32* %ptr
+ call void @readnone_but_may_throw()
+ store i32 20, i32* %ptr
+ ret void
+}
+
+define void @f_1(i1 %cond, i32* %ptr) {
+; CHECK-LABEL: @f_1(
+; CHECK: store i32 10, i32* %ptr
+; CHECK-NEXT: call void @readnone_but_may_throw()
+
+ store i32 10, i32* %ptr
+ call void @readnone_but_may_throw()
+ br i1 %cond, label %left, label %merge
+
+left:
+ store i32 20, i32* %ptr
+ br label %merge
+
+merge:
+ ret void
+}