[InstCombine] Provide more test cases for cast-folding [NFC]

[mreisinger]

Summary

In r275989 we enabled the folding of logic(cast(icmp), cast(icmp)) to cast(logic(icmp, icmp)). Here we add more test cases to assure this folding works for all logical operations and/or/xor.

[grosser]

Committed in https://llvm.org/svn/llvm-project/llvm/trunk@276105

test/Transforms/InstCombine/zext.ll

 ; CHECK-NEXT:    ret <2 x i64> [[XOR]]
 ;
   %zext1 = zext <2 x i1> %a to <2 x i32>
   %xor = xor <2 x i32> %zext1, <i32 1, i32 1>
   %zext2 = zext <2 x i32> %xor to <2 x i64>
   ret <2 x i64> %zext2
 }
 
-; Assert that zexts in logic(zext(icmp), zext(icmp)) can be folded
-; CHECK-LABEL: @fold_logic_zext_icmp(
+; Assert that zexts in and(zext(icmp), zext(icmp)) can be folded
+; CHECK-LABEL: @fold_and_zext_icmp(
 ; CHECK-NEXT:    [[ICMP1:%.*]] = icmp sgt i64 %a, %b
 ; CHECK-NEXT:    [[ICMP2:%.*]] = icmp slt i64 %a, %c
 ; CHECK-NEXT:    [[AND:%.*]] = and i1 [[ICMP1]], [[ICMP2]]
 ; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[AND]] to i8
 ; CHECK-NEXT:    ret i8 [[ZEXT]]
-define i8 @fold_logic_zext_icmp(i64 %a, i64 %b, i64 %c) {
+define i8 @fold_and_zext_icmp(i64 %a, i64 %b, i64 %c) {
   %1 = icmp sgt i64 %a, %b
   %2 = zext i1 %1 to i8
   %3 = icmp slt i64 %a, %c
   %4 = zext i1 %3 to i8
   %5 = and i8 %2, %4
   ret i8 %5
 }
 
+; Assert that zexts in or(zext(icmp), zext(icmp)) can be folded
+; CHECK-LABEL: @fold_or_zext_icmp(
+; CHECK-NEXT:    [[ICMP1:%.*]] = icmp sgt i64 %a, %b
+; CHECK-NEXT:    [[ICMP2:%.*]] = icmp slt i64 %a, %c
+; CHECK-NEXT:    [[OR:%.*]] = or i1 [[ICMP1]], [[ICMP2]]
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[OR]] to i8
+; CHECK-NEXT:    ret i8 [[ZEXT]]
+define i8 @fold_or_zext_icmp(i64 %a, i64 %b, i64 %c) {
+  %1 = icmp sgt i64 %a, %b
+  %2 = zext i1 %1 to i8
+  %3 = icmp slt i64 %a, %c
+  %4 = zext i1 %3 to i8
+  %5 = or i8 %2, %4
+  ret i8 %5
+}
+
+; Assert that zexts in xor(zext(icmp), zext(icmp)) can be folded
+; CHECK-LABEL: @fold_xor_zext_icmp(
+; CHECK-NEXT:    [[ICMP1:%.*]] = icmp sgt i64 %a, %b
+; CHECK-NEXT:    [[ICMP2:%.*]] = icmp slt i64 %a, %c
+; CHECK-NEXT:    [[XOR:%.*]] = xor i1 [[ICMP1]], [[ICMP2]]
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[XOR]] to i8
+; CHECK-NEXT:    ret i8 [[ZEXT]]
+define i8 @fold_xor_zext_icmp(i64 %a, i64 %b, i64 %c) {
+  %1 = icmp sgt i64 %a, %b
+  %2 = zext i1 %1 to i8
+  %3 = icmp slt i64 %a, %c
+  %4 = zext i1 %3 to i8
+  %5 = xor i8 %2, %4
+  ret i8 %5
+}
+
 ; Assert that zexts in logic(zext(icmp), zext(icmp)) are also folded accross
 ; nested logical operators.
 ; CHECK-LABEL: @fold_nested_logic_zext_icmp(
 ; CHECK-NEXT:    [[ICMP1:%.*]] = icmp sgt i64 %a, %b
 ; CHECK-NEXT:    [[ICMP2:%.*]] = icmp slt i64 %a, %c
 ; CHECK-NEXT:    [[AND:%.*]] = and i1 [[ICMP1]], [[ICMP2]]
 ; CHECK-NEXT:    [[ICMP3:%.*]] = icmp eq i64 %a, %d
 ; CHECK-NEXT:    [[OR:%.*]] = or i1 [[AND]], [[ICMP3]]