On Wed, Nov 18, 2015 at 11:06 AM, Eric Botcazou <ebotca...@adacore.com> wrote: > Hi, > > this is the underlying issue of PR middle-end/65958: the compiler generates > wrong code when alloca is used in conjunction with a VLA since the latter > causes the stack space allocated to the former to be wrongly reclaimed. > So the proposed fix is not to reclaim any stack space in this case. > > Bootstrapped/regtested on x86_64-suse-linux, OK for mainline and 5.x branch?
Ok. I wonder if we document GCCs VLA implementation somewhere so we can add a note on the interaction with alloca. Thanks, Richard. > > 2015-11-18 Eric Botcazou <ebotca...@adacore.com> > > PR middle-end/65958 > * gimplify.c (struct gimplify_ctx): Turn boolean fields into 1-bit > fields, add keep_stack and reorder them. > (gimplify_bind_expr): Save gimplify_ctxp->keep_stack on entry then > set it to false. Do not insert a stack save/restore pair if it has > been set to true by the gimplification of the statements. > Restore it to the saved value on exit if it is still false. > (gimplify_vla_decl): Do not set gimplify_ctxp->save_stack here. > (gimplify_call_expr) <BUILT_IN_ALLOCA[_WITH_ALIGN]>: New case. Set > either save_stack or keep_stack depending on CALL_ALLOCA_FOR_VAR_P. > > > 2015-11-18 Eric Botcazou <ebotca...@adacore.com> > > * gcc.dg/vla-24.c: New test. > > -- > Eric Botcazou
