[Test] Add test for PR60234

#60234 explains how widening
of a branch by loop-invariant condition is causing a miscompile.

llvm/test/Transforms/GuardWidening/pr60234.ll

@@ -0,0 +1,76 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes=indvars,guard-widening -S < %s | FileCheck %s
+
+declare i32 @llvm.experimental.deoptimize.i32(...)
+
+; FIXME: Make sure that guard widening does not turn loop-invariant condition
+;        (that then gets optimized basing on this fact) into non-invariant.
+;        https://github.com/llvm/llvm-project/issues/60234 explains how it causes
+;        a miscompile.
+define i32 @test(i32 %start) {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[WC1:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[START:%.*]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT:    [[START_PLUS_1:%.*]] = add i32 [[START]], 1
+; CHECK-NEXT:    [[COND:%.*]] = icmp ne i32 [[START_PLUS_1]], [[IV]]
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = and i1 true, [[COND]]
+; CHECK-NEXT:    [[TMP0:%.*]] = and i1 [[WIDE_CHK]], [[WC1]]
+; CHECK-NEXT:    br i1 [[TMP0]], label [[GUARD_BLOCK:%.*]], label [[EXIT_BY_WC:%.*]]
+; CHECK:       exit_by_wc:
+; CHECK-NEXT:    [[IV_LCSSA:%.*]] = phi i32 [ [[START]], [[LOOP]] ]
+; CHECK-NEXT:    [[RVAL1:%.*]] = call i32 (...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 [[IV_LCSSA]]) ]
+; CHECK-NEXT:    ret i32 [[RVAL1]]
+; CHECK:       guard_block:
+; CHECK-NEXT:    [[WC2:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[GUARD:%.*]] = and i1 [[COND]], [[WC2]]
+; CHECK-NEXT:    br i1 true, label [[BACKEDGE]], label [[FAILURE:%.*]]
+; CHECK:       backedge:
+; CHECK-NEXT:    call void @side_effect()
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
+; CHECK-NEXT:    br label [[LOOP]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i32 -1
+; CHECK:       failure:
+; CHECK-NEXT:    [[IV_LCSSA1:%.*]] = phi i32 [ [[IV]], [[GUARD_BLOCK]] ]
+; CHECK-NEXT:    [[RVAL2:%.*]] = call i32 (...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 [[IV_LCSSA1]]) ]
+; CHECK-NEXT:    ret i32 [[RVAL2]]
+;
+entry:
+  %wc1 = call i1 @llvm.experimental.widenable.condition()
+  br label %loop
+
+loop:
+  %iv = phi i32 [ %start, %entry ], [ %iv.next, %backedge ]
+  br i1 %wc1, label %guard_block, label %exit_by_wc
+
+exit_by_wc:
+  %rval1 = call i32(...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 %iv) ]
+  ret i32 %rval1
+
+guard_block:
+  %start_plus_1 = add i32 %start, 1
+  %cond = icmp ne i32 %start_plus_1, %iv
+  %wc2 = call i1 @llvm.experimental.widenable.condition()
+  %guard = and i1 %cond, %wc2
+  br i1 %guard, label %backedge, label %failure
+
+backedge:
+  call void @side_effect()
+  %iv.next = add i32 %iv, 1
+  br label %loop
+
+exit:
+  ret i32 -1
+
+failure:
+  %rval2 = call i32(...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 %iv) ]
+  ret i32 %rval2
+}
+
+; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(inaccessiblemem: readwrite)
+declare i1 @llvm.experimental.widenable.condition()
+
+declare void @side_effect()