[InstSimplify] vector div/rem with any zero element in divisor is undef
This was suggested as a DAG simplification in the review for rL297026 :
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170306/435253.html
...but let's start with IR since we have actual docs for IR (LangRef).
Differential Revision:
https://reviews.llvm.org/D30665
llvm-svn: 297390
diff --git a/llvm/test/Transforms/InstSimplify/div.ll b/llvm/test/Transforms/InstSimplify/div.ll
index 3136f02..f0d6fbb 100644
--- a/llvm/test/Transforms/InstSimplify/div.ll
+++ b/llvm/test/Transforms/InstSimplify/div.ll
@@ -1,11 +1,10 @@
; RUN: opt < %s -instsimplify -S | FileCheck %s
-; FIXME: Division-by-zero is undef. UB in any vector lane means the whole op is undef.
+; Division-by-zero is undef. UB in any vector lane means the whole op is undef.
define <2 x i8> @sdiv_zero_elt_vec(<2 x i8> %x) {
; CHECK-LABEL: @sdiv_zero_elt_vec(
-; CHECK-NEXT: [[DIV:%.*]] = sdiv <2 x i8> %x, <i8 -42, i8 0>
-; CHECK-NEXT: ret <2 x i8> [[DIV]]
+; CHECK-NEXT: ret <2 x i8> undef
;
%div = sdiv <2 x i8> %x, <i8 -42, i8 0>
ret <2 x i8> %div
@@ -13,8 +12,7 @@
define <2 x i8> @udiv_zero_elt_vec(<2 x i8> %x) {
; CHECK-LABEL: @udiv_zero_elt_vec(
-; CHECK-NEXT: [[DIV:%.*]] = udiv <2 x i8> %x, <i8 0, i8 42>
-; CHECK-NEXT: ret <2 x i8> [[DIV]]
+; CHECK-NEXT: ret <2 x i8> undef
;
%div = udiv <2 x i8> %x, <i8 0, i8 42>
ret <2 x i8> %div