[InstSimplify] fold srem with sext bool divisor
llvm-svn: 335616
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 4f5bed9..4a80558 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -1099,6 +1099,12 @@
/// If not, this returns null.
static Value *SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
unsigned MaxRecurse) {
+ // If the divisor is 0, the result is undefined, so assume the divisor is -1.
+ // srem Op0, (sext i1 X) --> srem Op0, -1 --> 0
+ Value *X;
+ if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))
+ return ConstantInt::getNullValue(Op0->getType());
+
return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse);
}
diff --git a/llvm/test/Transforms/InstSimplify/rem.ll b/llvm/test/Transforms/InstSimplify/rem.ll
index 54a7b5b..e18ff56 100644
--- a/llvm/test/Transforms/InstSimplify/rem.ll
+++ b/llvm/test/Transforms/InstSimplify/rem.ll
@@ -309,9 +309,7 @@
define i32 @srem_with_sext_bool_divisor(i1 %x, i32 %y) {
; CHECK-LABEL: @srem_with_sext_bool_divisor(
-; CHECK-NEXT: [[S:%.*]] = sext i1 [[X:%.*]] to i32
-; CHECK-NEXT: [[R:%.*]] = srem i32 [[Y:%.*]], [[S]]
-; CHECK-NEXT: ret i32 [[R]]
+; CHECK-NEXT: ret i32 0
;
%s = sext i1 %x to i32
%r = srem i32 %y, %s
@@ -320,9 +318,7 @@
define <2 x i32> @srem_with_sext_bool_divisor_vec(<2 x i1> %x, <2 x i32> %y) {
; CHECK-LABEL: @srem_with_sext_bool_divisor_vec(
-; CHECK-NEXT: [[S:%.*]] = sext <2 x i1> [[X:%.*]] to <2 x i32>
-; CHECK-NEXT: [[R:%.*]] = srem <2 x i32> [[Y:%.*]], [[S]]
-; CHECK-NEXT: ret <2 x i32> [[R]]
+; CHECK-NEXT: ret <2 x i32> zeroinitializer
;
%s = sext <2 x i1> %x to <2 x i32>
%r = srem <2 x i32> %y, %s