[InstCombine] Add tests for `(icmp eq/ne bitreverse(x), C)`; NFC

[nikic]

Could you please add a negative test with a non-equality predicate? (We should not fold e.g. icmp ult.)

[goldstein.w.n]

Add negative test

[goldstein.w.n]

In D145338#4170793, @nikic wrote:

Could you please add a negative test with a non-equality predicate? (We should not fold e.g. icmp ult.)

Done.

[nikic]

LGTM

llvm/test/Transforms/InstCombine/cmp-intrinsic.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -passes=instcombine -S | FileCheck %s
 
 declare i16 @llvm.bswap.i16(i16)
 declare i32 @llvm.bswap.i32(i32)
 declare <2 x i64> @llvm.bswap.v2i64(<2 x i64>)
 declare i32 @llvm.cttz.i32(i32, i1)
 declare i33 @llvm.cttz.i33(i33, i1)
 declare i32 @llvm.ctlz.i32(i32, i1)
 declare i33 @llvm.ctlz.i33(i33, i1)
 declare i8 @llvm.ctpop.i8(i8)
 declare i11 @llvm.ctpop.i11(i11)
 declare <2 x i32> @llvm.cttz.v2i32(<2 x i32>, i1)
 declare <2 x i32> @llvm.ctlz.v2i32(<2 x i32>, i1)
 declare <2 x i32> @llvm.ctpop.v2i32(<2 x i32>)
+declare i8 @llvm.bitreverse.i8(i8)
+declare <2 x i8> @llvm.bitreverse.v2i8(<2 x i8>)
 declare void @use6(i6)
 
 define i1 @bswap_eq_i16(i16 %x) {
 ; CHECK-LABEL: @bswap_eq_i16(
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i16 [[X:%.*]], 256
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %bs = call i16 @llvm.bswap.i16(i16 %x)

 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i4 [[TRUNC]], 7
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %tz = tail call i33 @llvm.cttz.i33(i33 %x, i1 false)
   %trunc = trunc i33 %tz to i4
   %cmp = icmp ult i4 %trunc, 7
   ret i1 %cmp
 }
+
+define i1 @bitreverse_ne_22(i8 %x) {
+; CHECK-LABEL: @bitreverse_ne_22(
+; CHECK-NEXT:    [[Y:%.*]] = call i8 @llvm.bitreverse.i8(i8 [[X:%.*]])
+; CHECK-NEXT:    [[Z:%.*]] = icmp ne i8 [[Y]], 22
+; CHECK-NEXT:    ret i1 [[Z]]
+;
+  %y = call i8 @llvm.bitreverse.i8(i8 %x)
+  %z = icmp ne i8 %y, 22
+  ret i1 %z
+}
+
+define <2 x i1> @bitreverse_vec_eq_2_2(<2 x i8> %x) {
+; CHECK-LABEL: @bitreverse_vec_eq_2_2(
+; CHECK-NEXT:    [[Y:%.*]] = call <2 x i8> @llvm.bitreverse.v2i8(<2 x i8> [[X:%.*]])
+; CHECK-NEXT:    [[Z:%.*]] = icmp eq <2 x i8> [[Y]], <i8 2, i8 2>
+; CHECK-NEXT:    ret <2 x i1> [[Z]]
+;
+  %y = call <2 x i8> @llvm.bitreverse.v2i8(<2 x i8> %x)
+  %z = icmp eq <2 x i8> %y, <i8 2, i8 2>
+  ret <2 x i1> %z
+}
+
+define <2 x i1> @bitreverse_vec_eq_1_2_todo_no_splat(<2 x i8> %x) {
+; CHECK-LABEL: @bitreverse_vec_eq_1_2_todo_no_splat(
+; CHECK-NEXT:    [[Y:%.*]] = call <2 x i8> @llvm.bitreverse.v2i8(<2 x i8> [[X:%.*]])
+; CHECK-NEXT:    [[Z:%.*]] = icmp eq <2 x i8> [[Y]], <i8 1, i8 2>
+; CHECK-NEXT:    ret <2 x i1> [[Z]]
+;
+  %y = call <2 x i8> @llvm.bitreverse.v2i8(<2 x i8> %x)
+  %z = icmp eq <2 x i8> %y, <i8 1, i8 2>
+  ret <2 x i1> %z
+}