Add a microoptimization for urem.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186235 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index e94f719..eac24c6 100644
--- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -1125,6 +1125,13 @@
return BinaryOperator::CreateAnd(Op0, Add);
}
+ // 1 urem X -> zext(X != 1)
+ if (match(Op0, m_One())) {
+ Value *Cmp = Builder->CreateICmpNE(Op1, Op0);
+ Value *Ext = Builder->CreateZExt(Cmp, I.getType());
+ return ReplaceInstUsesWith(I, Ext);
+ }
+
return 0;
}
diff --git a/test/Transforms/InstCombine/rem.ll b/test/Transforms/InstCombine/rem.ll
index 808d51e..c6fd721 100644
--- a/test/Transforms/InstCombine/rem.ll
+++ b/test/Transforms/InstCombine/rem.ll
@@ -163,3 +163,12 @@
%rem = urem i32 %x, %add
ret i32 %rem
}
+
+define i32 @test17(i32 %X) {
+; CHECK: @test17
+; CHECK-NEXT: icmp ne i32 %X, 1
+; CHECK-NEXT: zext i1
+; CHECK-NEXT: ret
+ %A = urem i32 1, %X
+ ret i32 %A
+}