[llvm] [ConstantRange] Improve ConstantRange::binaryXor (PR #80146)

[via llvm-commits]

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@@ -0,0 +1,55 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt < %s -passes=ipsccp -S | FileCheck %s
+
+; Tests from PR79696
+
+define i1 @constant_range_xor(i64 %a) {
+; CHECK-LABEL: define i1 @constant_range_xor(
+; CHECK-SAME: i64 [[A:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i64 [[A]], 8192
+; CHECK-NEXT:    br i1 [[CMP]], label [[THEN:%.*]], label [[ELSE:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    [[CTLZ:%.*]] = call i64 @llvm.ctlz.i64(i64 [[A]], i1 true)
+; CHECK-NEXT:    [[CONV:%.*]] = xor i64 [[CTLZ]], 63
+; CHECK-NEXT:    ret i1 false
+; CHECK:       else:
+; CHECK-NEXT:    ret i1 false
+;
+entry:
+  %cmp = icmp ugt i64 %a, 8192
+  br i1 %cmp, label %then, label %else
+then:
+  %ctlz = call i64 @llvm.ctlz.i64(i64 %a, i1 true) ;[0, 50]
+  %conv = xor i64 %ctlz, 63                        ;[13, 63]
+  %cmp1 = icmp ult i64 %conv, 13
+  ret i1 %cmp1
+else:
+  ret i1 false
+}
+
+define i1 @constant_range_xor_negative(i64 %a) {
+; CHECK-LABEL: define i1 @constant_range_xor_negative(
+; CHECK-SAME: i64 [[A:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i64 [[A]], 8192
+; CHECK-NEXT:    br i1 [[CMP]], label [[THEN:%.*]], label [[ELSE:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    [[CTLZ:%.*]] = call i64 @llvm.ctlz.i64(i64 [[A]], i1 true)
+; CHECK-NEXT:    [[CONV:%.*]] = xor i64 [[CTLZ]], 62
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i64 [[CONV]], 13
+; CHECK-NEXT:    ret i1 [[CMP1]]
+; CHECK:       else:
+; CHECK-NEXT:    ret i1 false
+;
+entry:
+  %cmp = icmp ugt i64 %a, 8192
+  br i1 %cmp, label %then, label %else
+then:
+  %ctlz = call i64 @llvm.ctlz.i64(i64 %a, i1 true) ;[0, 50]
+  %conv = xor i64 %ctlz, 62                        ;[12, 63]
+  %cmp1 = icmp ult i64 %conv, 13
+  ret i1 %cmp1
+else:
+  ret i1 false
+}
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XChy wrote:

Apart from the test in original issue, I'm happy with more tests involving more variables. You can use `or` or `and` to generate some positive/negative tests as [this one](https://alive2.llvm.org/ce/z/BUgpqP) does.

https://github.com/llvm/llvm-project/pull/80146