https://bugs.llvm.org/show_bug.cgi?id=32450
Bug ID: 32450
Summary: CallGraph failed to identify some direct calls'
targets
Product: new-bugs
Version: 3.9
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: new bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Attached are LLVM assembly and bitcode files to reproduce the problem. I also
attached the callgraph retrieved from opt. They are compiled from musl libc
version 1.1.16 with LLVM LTO.
The callgraph generated by opt from this bitcode shows only 1 direct callee of
function __fwritex.
Call graph node for function: '__fwritex'<<0x6784590>> #uses=5
CS<0x61b65e0> calls external node
CS<0x61b7080> calls external node
CS<0x61b8260> calls external node
CS<0x61b8d20> calls function 'memcpy'
However, source code says there is another direct callsite to __towrite. This
is compiled into a direct call in the result binary as well.
size_t __fwritex(const unsigned char *restrict s, size_t l, FILE *restrict f)
{
size_t i=0;
if (!f->wend && __towrite(f)) return 0;
if (l > f->wend - f->wpos) return f->write(f, s, l);
if (f->lbf >= 0) {
/* Match /^(.*\n|)/ */
for (i=l; i && s[i-1] != '\n'; i--);
if (i) {
size_t n = f->write(f, s, i);
if (n < i) return n;
s += i;
l -= i;
}
}
memcpy(f->wpos, s, l);
f->wpos += l;
return l+i;
}
Another example is function _flushlbf where the direct call to fflush does not
show up in its callgraph. This also appears as a direct call in executable.
void _flushlbf(void)
{
fflush(0);
}
Call graph node for function: '_flushlbf'<<0x6782160>> #uses=1
CS<0x6151c40> calls external node
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