[clang] [ubsan] Connect -fsanitize-skip-hot-cutoff to LowerAllowCheckPass<cutoffs> (PR #124857)

[Thurston Dang via cfe-commits]

================
@@ -7,18 +10,26 @@
 // CHECK-LABEL: define dso_local noundef i32 @div(
 // CHECK-SAME: i32 noundef [[X:%.*]], i32 noundef [[Y:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
 // CHECK-NEXT:  [[ENTRY:.*:]]
-// CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i32 [[Y]], 0, !nosanitize [[META2:![0-9]+]]
-// CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[X]], -2147483648, !nosanitize [[META2]]
-// CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[Y]], -1, !nosanitize [[META2]]
-// CHECK-NEXT:    [[OR_NOT5:%.*]] = and i1 [[TMP1]], [[TMP2]]
-// CHECK-NEXT:    [[DOTNOT3:%.*]] = or i1 [[TMP0]], [[OR_NOT5]]
-// CHECK-NEXT:    [[TMP3:%.*]] = tail call i1 @llvm.allow.ubsan.check(i8 3), !nosanitize [[META2]]
-// CHECK-NEXT:    [[DOTNOT1:%.*]] = and i1 [[DOTNOT3]], [[TMP3]]
-// CHECK-NEXT:    br i1 [[DOTNOT1]], label %[[HANDLER_DIVREM_OVERFLOW:.*]], label %[[CONT:.*]], !prof [[PROF3:![0-9]+]], !nosanitize [[META2]]
+// CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i32 [[Y]], 0, !nosanitize [[META2:![0-9]+]]
+// CHECK-NEXT:    [[TMP1:%.*]] = icmp ne i32 [[X]], -2147483648, !nosanitize [[META2]]
+// CHECK-NEXT:    [[TMP2:%.*]] = icmp ne i32 [[Y]], -1, !nosanitize [[META2]]
+// CHECK-NEXT:    [[OR:%.*]] = or i1 [[TMP1]], [[TMP2]], !nosanitize [[META2]]
+//
+//                                                                       27 == SO_IntegerDivideByZero
+// CHECK-NEXT:    [[TMP3:%.*]] = tail call i1 @llvm.allow.ubsan.check(i8 27), !nosanitize [[META2]]
+// CHECK-NEXT:    [[TMP4:%.*]] = xor i1 [[TMP3]], true, !nosanitize [[META2]]
+// CHECK-NEXT:    [[TMP5:%.*]] = or i1 [[TMP0]], [[TMP4]], !nosanitize [[META2]]
+//
+//                                                                       41 == SO_SignedIntegerOverflow
+// CHECK-NEXT:    [[TMP6:%.*]] = tail call i1 @llvm.allow.ubsan.check(i8 41), !nosanitize [[META2]]
+// CHECK-NEXT:    [[TMP7:%.*]] = xor i1 [[TMP6]], true, !nosanitize [[META2]]
----------------
thurstond wrote:

The old instrumentation was:
```
 (Check1 && Check2 && ... && !allow_ubsan_check) 
```
The problem is each check might have a different SanitizerKind, but we can only specify one threshold for the lone allow_ubsan_check.

This patch changes the instrumentation to:
```
 (Check1 || !allow_ubsan_check) && (Check2 || !allow_ubsan_check) ...
```
hence we can have individual thresholds for each check. In this case I've annotated that the check parameters are `27 == SO_IntegerDivideByZero` and `41 == SO_SignedIntegerOverflow`.

https://github.com/llvm/llvm-project/pull/124857