| Message ID | 20180209054247.GG3846@bubble.grove.modra.org |
|---|---|
| State | New |
| Headers | show |
| Series | PR84300, ICE in dwarf2cfi on ppc64le | expand |
On Fri, Feb 09, 2018 at 04:12:47PM +1030, Alan Modra wrote: > This PR is one of those with a really obvious cause, and fix. There's > nothing in the unspec rtl to say the insn needs lr! > Bootstrapped and regression tested powerpc64le-linux. OK? > > PR target/84300 > gcc/ > * config/rs6000/rs6000.md (split_stack_return): Use LR. > gcc/testsuite/ > * gcc.dg/pr84300.c: New. > > diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md > index 33f0d95..287461f 100644 > --- a/gcc/config/rs6000/rs6000.md > +++ b/gcc/config/rs6000/rs6000.md > @@ -13359,7 +13359,8 @@ (define_insn "load_split_stack_limit_si" > ;; Use r0 to stop regrename twiddling with lr restore insns emitted > ;; after the call to __morestack. > (define_insn "split_stack_return" > - [(unspec_volatile [(use (reg:SI 0))] UNSPECV_SPLIT_STACK_RETURN)] > + [(unspec_volatile [(use (reg:SI 0)) (use (reg:SI LR_REGNO))] > + UNSPECV_SPLIT_STACK_RETURN)] I'm not sure what a USE as input of an UNSPEC means -- it should work without the USEs? So please try without; otherwise okay of course. Thanks! Segher
On Fri, Feb 09, 2018 at 08:11:44AM -0600, Segher Boessenkool wrote: > On Fri, Feb 09, 2018 at 04:12:47PM +1030, Alan Modra wrote: > > ;; Use r0 to stop regrename twiddling with lr restore insns emitted > > ;; after the call to __morestack. > > (define_insn "split_stack_return" > > - [(unspec_volatile [(use (reg:SI 0))] UNSPECV_SPLIT_STACK_RETURN)] > > + [(unspec_volatile [(use (reg:SI 0)) (use (reg:SI LR_REGNO))] > > + UNSPECV_SPLIT_STACK_RETURN)] > > I'm not sure what a USE as input of an UNSPEC means -- it should work > without the USEs? Hmm, yes, plain [(reg:SI 0) (reg:SI LR_REGNO)] ought to work. A sniff test says it's OK but I'll do the whole bootstrap/regtest cycle before committing. I'm not sure why I put the USE there for r0, probably because I had the r0 dependency outside the unspec initially then decided it could replace (const_int 0) inside the unspec vector to save on useless RTL. I didn't go far enough in trimming the RTL..
On Sat, Feb 10, 2018 at 02:09:57PM +1030, Alan Modra wrote: > On Fri, Feb 09, 2018 at 08:11:44AM -0600, Segher Boessenkool wrote: > > On Fri, Feb 09, 2018 at 04:12:47PM +1030, Alan Modra wrote: > > > ;; Use r0 to stop regrename twiddling with lr restore insns emitted > > > ;; after the call to __morestack. > > > (define_insn "split_stack_return" > > > - [(unspec_volatile [(use (reg:SI 0))] UNSPECV_SPLIT_STACK_RETURN)] > > > + [(unspec_volatile [(use (reg:SI 0)) (use (reg:SI LR_REGNO))] > > > + UNSPECV_SPLIT_STACK_RETURN)] > > > > I'm not sure what a USE as input of an UNSPEC means -- it should work > > without the USEs? > > Hmm, yes, plain [(reg:SI 0) (reg:SI LR_REGNO)] ought to work. A sniff > test says it's OK but I'll do the whole bootstrap/regtest cycle before > committing. I'm not sure why I put the USE there for r0, probably > because I had the r0 dependency outside the unspec initially then > decided it could replace (const_int 0) inside the unspec vector to > save on useless RTL. I didn't go far enough in trimming the RTL.. For R0 you can use a USE I think, but it should be in a parallel with the unspec then. But LR more appropriately is an input to the unspec, it's not just there to keep the register alive for <some reason>. Having both as inputs works of course. Segher
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md index 33f0d95..287461f 100644 --- a/gcc/config/rs6000/rs6000.md +++ b/gcc/config/rs6000/rs6000.md @@ -13359,7 +13359,8 @@ (define_insn "load_split_stack_limit_si" ;; Use r0 to stop regrename twiddling with lr restore insns emitted ;; after the call to __morestack. (define_insn "split_stack_return" - [(unspec_volatile [(use (reg:SI 0))] UNSPECV_SPLIT_STACK_RETURN)] + [(unspec_volatile [(use (reg:SI 0)) (use (reg:SI LR_REGNO))] + UNSPECV_SPLIT_STACK_RETURN)] "" "blr" [(set_attr "type" "jmpreg")]) diff --git a/gcc/testsuite/gcc.dg/pr84300.c b/gcc/testsuite/gcc.dg/pr84300.c new file mode 100644 index 0000000..6016799 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr84300.c @@ -0,0 +1,5 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target split_stack } */ +/* { dg-options "-g -O2 -fsplit-stack -fno-omit-frame-pointer" } */ + +void trap () { __builtin_trap (); }