https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88936
--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> --- Created attachment 45605 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45605&action=edit prototype conservative fix So this is a very conservative fix computing what automatic variables "escape" and duplicating those with (a single) shadow variable. It FAILs at least the following test (though IPA PTA has low testsuite coverage) FAIL: gcc.dg/ipa/ipa-pta-3.c scan-tree-dump fre3 "Replaced \\*p_2\\(D\\) with 1" The testcase tests optimization on static int __attribute__((noinline,noclone)) foo (int *p, int *q) { *p = 1; *q = 0; return *p; } extern void abort (void); int main() { int a, b; if (foo (&a, &b) != 1) abort (); return 0; } where you see we now compute a and b as escaping and thus add SHADOW to the points-to sets of both p and q making them appear aliasing. Missed optimizations of the patch are a) main isn't reached recursively so we never need shadow vars for a or b b) we could have used separate shadow vars for a and b The patch has the opportunity to provide the missing local escaped solution. In practice the opportunity to cut non-recursively reached functions is probably low - I've yet have to identify a conservative way to compute this.
