[InstCombine] add tests to show pattern matching failures due to commutation

I was looking to fix a bug in getComplexity(), and these cases showed up as 
obvious failures. I'm not sure how to find these in general though.

llvm-svn: 281055

1 files changed, 55 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/or.ll b/llvm/test/Transforms/InstCombine/or.ll
index 4fb1978615d..38b8ebc5adf 100644
--- a/llvm/test/Transforms/InstCombine/or.ll
+++ b/llvm/test/Transforms/InstCombine/or.ll
@@ -555,6 +555,8 @@ define i32 @test41(i32 %a, i32 %b) {
   ret i32 %or
 }
 
+; (~A ^ B) | (A & B) -> (~A ^ B)
+
 define i32 @test42(i32 %a, i32 %b) {
 ; CHECK-LABEL: @test42(
 ; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 %a, -1
@@ -568,6 +570,42 @@ define i32 @test42(i32 %a, i32 %b) {
   ret i32 %or
 }
 
+; FIXME: We miss the fold because the pattern matching is inadequate.
+
+define i32 @test42_commuted_and(i32 %a, i32 %b) {
+; CHECK-LABEL: @test42_commuted_and(
+; CHECK-NEXT:    [[NEGA:%.*]] = xor i32 %a, -1
+; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[NEGA]], %b
+; CHECK-NEXT:    [[AND:%.*]] = and i32 %b, %a
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[XOR]], [[AND]]
+; CHECK-NEXT:    ret i32 [[OR]]
+;
+  %nega = xor i32 %a, -1
+  %xor = xor i32 %nega, %b
+  %and = and i32 %b, %a
+  %or = or i32 %xor, %and
+  ret i32 %or
+}
+
+; FIXME: We miss the fold because the pattern matching is inadequate.
+
+define i32 @test42_commuted_xor(i32 %a, i32 %b) {
+; CHECK-LABEL: @test42_commuted_xor(
+; CHECK-NEXT:    [[NEGA:%.*]] = xor i32 %a, -1
+; CHECK-NEXT:    [[XOR:%.*]] = xor i32 %b, [[NEGA]]
+; CHECK-NEXT:    [[AND:%.*]] = and i32 %a, %b
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[XOR]], [[AND]]
+; CHECK-NEXT:    ret i32 [[OR]]
+;
+  %nega = xor i32 %a, -1
+  %xor = xor i32 %b, %nega
+  %and = and i32 %a, %b
+  %or = or i32 %xor, %and
+  ret i32 %or
+}
+
+; Commute operands of the 'or'.
+
 define i32 @test43(i32 %a, i32 %b) {
 ; CHECK-LABEL: @test43(
 ; CHECK-NEXT:    [[OR:%.*]] = xor i32 %a, %b
@@ -580,6 +618,23 @@ define i32 @test43(i32 %a, i32 %b) {
   ret i32 %or
 }
 
+; FIXME: We miss the fold because the pattern matching is inadequate.
+
+define i32 @test43_commuted_and(i32 %a, i32 %b) {
+; CHECK-LABEL: @test43_commuted_and(
+; CHECK-NEXT:    [[NEG:%.*]] = xor i32 %b, -1
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[NEG]], %a
+; CHECK-NEXT:    [[XOR:%.*]] = xor i32 %a, %b
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[AND]], [[XOR]]
+; CHECK-NEXT:    ret i32 [[OR]]
+;
+  %neg = xor i32 %b, -1
+  %and = and i32 %neg, %a
+  %xor = xor i32 %a, %b
+  %or = or i32 %and, %xor
+  ret i32 %or
+}
+
 define i32 @test44(i32 %a, i32 %b) {
 ; CHECK-LABEL: @test44(
 ; CHECK-NEXT:    [[OR:%.*]] = xor i32 %a, %b