1 files changed, 41 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/prevent-cmp-merge.ll b/llvm/test/Transforms/InstCombine/prevent-cmp-merge.ll
new file mode 100644
index 00000000000..ab37c7d5623
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/prevent-cmp-merge.ll
@@ -0,0 +1,41 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+;
+; This test makes sure that InstCombine does not replace the sequence of
+; xor/sub instruction followed by cmp instruction into a single cmp instruction
+; if there is more than one use of xor/sub.
+
+define zeroext i1 @test1(i32 %lhs, i32 %rhs) {
+; CHECK-LABEL: @test1(
+; CHECK-NEXT: %xor = xor i32 %lhs, 5
+; CHECK-NEXT: %cmp1 = icmp eq i32 %xor, 10
+
+  %xor = xor i32 %lhs, 5
+  %cmp1 = icmp eq i32 %xor, 10
+  %cmp2 = icmp eq i32 %xor, %rhs
+  %sel = or i1 %cmp1, %cmp2
+  ret i1 %sel
+}
+
+define zeroext i1 @test2(i32 %lhs, i32 %rhs) {
+; CHECK-LABEL: @test2(
+; CHECK-NEXT: %xor = xor i32 %lhs, %rhs
+; CHECK-NEXT: %cmp1 = icmp eq i32 %xor, 0
+
+  %xor = xor i32 %lhs, %rhs
+  %cmp1 = icmp eq i32 %xor, 0
+  %cmp2 = icmp eq i32 %xor, 32
+  %sel = xor i1 %cmp1, %cmp2
+  ret i1 %sel
+}
+
+define zeroext i1 @test3(i32 %lhs, i32 %rhs) {
+; CHECK-LABEL: @test3(
+; CHECK-NEXT: %sub = sub nsw i32 %lhs, %rhs
+; CHECK-NEXT: %cmp1 = icmp eq i32 %sub, 0
+
+  %sub = sub nsw i32 %lhs, %rhs
+  %cmp1 = icmp eq i32 %sub, 0
+  %cmp2 = icmp eq i32 %sub, 31
+  %sel = or i1 %cmp1, %cmp2
+  ret i1 %sel
+}