================
@@ -194,3 +194,34 @@ char test_comparison_with_extent_symbol(struct incomplete
*p) {
return ((char *)p)[-1]; // no-warning
}
+int table[256], small_table[128];
+int test_cast_to_unsigned(signed char x) {
+ unsigned char y = x;
+ if (x >= 0)
+ return x;
+ // FIXME: Here the analyzer ignores the signed -> unsigned cast, and manages
to
+ // load a negative value from an unsigned variable. This causes an underflow
+ // report, which is an ugly false positive.
+ // The underlying issue is tracked by Github ticket #39492.
+ return table[y]; // expected-warning {{Out of bound access to memory
preceding}}
----------------
NagyDonat wrote:
Yep, that seems to be useful, I added the value dumps to the two testcases
where they are relevant. (The third testcase is not buggy, I just created it to
highlight potential drawbacks of naive solutions for silencing the bug.)
https://github.com/llvm/llvm-project/pull/127062
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