[ConstraintElim] Add pre-commit tests. NFC.

Author: dtcxzyw

llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll

@@ -0,0 +1,36 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -p constraint-elimination -S %s | FileCheck %s
+
+define void @f(i32 noundef %v0, i32 noundef %v1, i32 noundef %v2) {
+; CHECK-LABEL: define void @f(
+; CHECK-SAME: i32 noundef [[V0:%.*]], i32 noundef [[V1:%.*]], i32 noundef [[V2:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    [[CMP0:%.*]] = icmp sge i32 [[V0]], [[V1]]
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp sge i32 [[V1]], [[V2]]
+; CHECK-NEXT:    [[AND1:%.*]] = and i1 [[CMP0]], [[CMP1]]
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[V0]], [[V2]]
+; CHECK-NEXT:    [[AND2:%.*]] = and i1 [[CMP2]], [[AND1]]
+; CHECK-NEXT:    br i1 [[AND2]], label %[[IF_THEN:.*]], label %[[RETURN:.*]]
+; CHECK:       [[IF_THEN]]:
+; CHECK-NEXT:    call void @side_effect()
+; CHECK-NEXT:    br label %[[RETURN]]
+; CHECK:       [[RETURN]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cmp0 = icmp sge i32 %v0, %v1
+  %cmp1 = icmp sge i32 %v1, %v2
+  %and1 = and i1 %cmp0, %cmp1
+  %cmp2 = icmp slt i32 %v0, %v2
+  %and2 = and i1 %cmp2, %and1
+  br i1 %and2, label %if.then, label %return
+
+if.then:
+  call void @side_effect()
+  br label %return
+
+return:
+  ret void
+}
+
+declare void @side_effect()