https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81877
--- Comment #8 from rguenther at suse dot de <rguenther at suse dot de> --- On Thu, 17 Aug 2017, amonakov at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81877 > > Alexander Monakov <amonakov at gcc dot gnu.org> changed: > > What |Removed |Added > ---------------------------------------------------------------------------- > CC| |amonakov at gcc dot gnu.org > > --- Comment #7 from Alexander Monakov <amonakov at gcc dot gnu.org> --- > Small C testcase demonstrating the issue with -O2 -fno-tree-sra: > > void g(int *out) > { > struct s {int x;} s; > #pragma GCC ivdep > for (int i = 0; i < 100; i++) > { > int *x = &s.x; > asm("" : "+r"(x)); > *x = 42; > out[i] = s.x; > } > } > > I think the main question is how safelen introduced via pragma-ivdep or > do-concurrent is supposed to interact with addressable vars written in the > loop > body? It doesn't seem well-defined?.. I think this one is simply undefined given the must-alias dependency isn't "obvious" (aka literal). The fortran case would be similar (it has a function call). But of course GCC itself could introduce above obfuscation.
