[llvm] r335616 - [InstSimplify] fold srem with sext bool divisor
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Tue Jun 26 08:32:54 PDT 2018
Author: spatel
Date: Tue Jun 26 08:32:54 2018
New Revision: 335616
URL: http://llvm.org/viewvc/llvm-project?rev=335616&view=rev
Log:
[InstSimplify] fold srem with sext bool divisor
Modified:
llvm/trunk/lib/Analysis/InstructionSimplify.cpp
llvm/trunk/test/Transforms/InstSimplify/rem.ll
Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=335616&r1=335615&r2=335616&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Tue Jun 26 08:32:54 2018
@@ -1099,6 +1099,12 @@ Value *llvm::SimplifyUDivInst(Value *Op0
/// 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);
}
Modified: llvm/trunk/test/Transforms/InstSimplify/rem.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/rem.ll?rev=335616&r1=335615&r2=335616&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/rem.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/rem.ll Tue Jun 26 08:32:54 2018
@@ -309,9 +309,7 @@ define i32 @rem10(i32 %x, i32 %y) {
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 i32 @srem_with_sext_bool_divisor(
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
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