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

[Bill Wendling 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));
----------------
bwendling wrote:

I'm not super worried about that construction, and it can get into very tricky situations. For instance, only the final expression is the "result" of the comma operator, the preceding expressions could be arbitrarily complex, and they cannot have side-effects. This is a can of worms that I want to keep shut (as I hope such usage is extremely rare)... :-)

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