[clang] [CodeGen][counted_by] See past parentheses and no-op casts (PR #151266)

[Shafik Yaghmour via cfe-commits]

================
@@ -471,3 +471,80 @@ size_t test9(struct annotated_sized_ptr *p, int index) {
 size_t test10(struct annotated_sized_ptr *p, int index) {
   return __bdos(&((unsigned int *) p->buf)[index]);
 }
+
+struct pr151236_struct {
+        int *a __counted_by(a_count);
+        short a_count;
+};
+
+// SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 -262144, 262137) i64 @test11(
+// SANITIZE-WITH-ATTR-SAME: ptr noundef [[P:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// SANITIZE-WITH-ATTR-NEXT:  entry:
+// SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_GEP:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_LOAD:%.*]] = load i16, ptr [[COUNTED_BY_GEP]], align 4
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = icmp sgt i16 [[COUNTED_BY_LOAD]], -1
+// SANITIZE-WITH-ATTR-NEXT:    [[COUNT:%.*]] = sext i16 [[COUNTED_BY_LOAD]] to i64
+// SANITIZE-WITH-ATTR-NEXT:    [[ARRAY_SIZE:%.*]] = shl nsw i64 [[COUNT]], 3
+// SANITIZE-WITH-ATTR-NEXT:    [[TMP1:%.*]] = select i1 [[TMP0]], i64 [[ARRAY_SIZE]], i64 0
+// SANITIZE-WITH-ATTR-NEXT:    ret i64 [[TMP1]]
+//
+// NO-SANITIZE-WITH-ATTR-LABEL: define dso_local range(i64 -262144, 262137) i64 @test11(
+// NO-SANITIZE-WITH-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]]) local_unnamed_addr #[[ATTR1]] {
+// NO-SANITIZE-WITH-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_GEP:%.*]] = getelementptr inbounds nuw i8, ptr [[P]], i64 8
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[COUNTED_BY_LOAD:%.*]] = load i16, ptr [[COUNTED_BY_GEP]], align 4
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[COUNT:%.*]] = sext i16 [[COUNTED_BY_LOAD]] to i64
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[ARRAY_SIZE:%.*]] = shl nsw i64 [[COUNT]], 3
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP0:%.*]] = icmp sgt i16 [[COUNTED_BY_LOAD]], -1
+// NO-SANITIZE-WITH-ATTR-NEXT:    [[TMP1:%.*]] = select i1 [[TMP0]], i64 [[ARRAY_SIZE]], i64 0
+// NO-SANITIZE-WITH-ATTR-NEXT:    ret i64 [[TMP1]]
+//
+// SANITIZE-WITHOUT-ATTR-LABEL: define dso_local range(i64 0, -1) i64 @test11(
+// SANITIZE-WITHOUT-ATTR-SAME: ptr noundef [[P:%.*]]) local_unnamed_addr #[[ATTR0]] {
+// SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// SANITIZE-WITHOUT-ATTR-NEXT:    ret i64 -2
+//
+// NO-SANITIZE-WITHOUT-ATTR-LABEL: define dso_local range(i64 0, -1) i64 @test11(
+// NO-SANITIZE-WITHOUT-ATTR-SAME: ptr noundef readonly captures(none) [[P:%.*]]) local_unnamed_addr #[[ATTR1]] {
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:  entry:
+// NO-SANITIZE-WITHOUT-ATTR-NEXT:    ret i64 -2
+//
+size_t test11(struct pr151236_struct *p) {
+  return __bdos(p->a) + __bdos((p->a));
----------------
shafik wrote:

So there are two concerns here 1) What is the behavior we expect and documenting that, via tests one way of doing that 2) Making sure we don't crash or some other bad behavior.

I spend a lot of time triaging and folks do plenty of stuff we don't expect and or discourage and if we can predict some of them in advance that saves us time later on.

https://github.com/llvm/llvm-project/pull/151266