Ping. thanks.
Qing > On Jan 28, 2022, at 12:03 PM, Qing Zhao via Gcc-patches > <gcc-patches@gcc.gnu.org> wrote: > > Hi, > > PR 100775 ( ICE: in df_exit_block_bitmap_verify, at df-scan.c:4164 with > -mthumb -fzero-call-used-regs=used) > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100775 > > Although the ICE only happens on arm, but this is a bug in the middle end. > So, I think this bug has higher priority, > Need to be included into gcc12, and also need to be back ported to gcc11. > > In the pass_zero_call_used_regs, when updating dataflow info after adding > the register zeroing sequence in the epilogue of the function, we should > call "df_update_exit_block_uses" to update the register use information in > the exit block to include all the registers that have been zeroed. > > The change has been bootstrapped and reg-tested on both x86 and aarch64 (with > -enable-checking=yes,rtl,df). > Since I cannot find an arm machine, no bootstrap and reg-tested on arm yet. > > For the arm failure, I just tested it with the cross build and it has no > issue withe the fix. > > (One question here: > Previously, I though “df_set_bb_dirty (EXIT_BLOCK_PTR_FOR_FN (cfun))” and a > later “df_analyze()” should rescan > the changed exit block of the function, and update all the df info > automatically, it apparently not the case, the register > use info at exit block is not automatically updated, we have to add an > explicitly call to “df_update_exit_block_uses”. > I checked the pass_thread_prologue_and_epilogue, looks like it also > explicitly calls “df_update_entry_exit_and_calls” > to update the register use info. > Shall the “df_set_bb_dirty” + “df_analyze” automatically update the reg use > info of the dirty block?). > > Let me know whether there is any issue with the fix? > > Thanks > > Qing > > =================================== > > From e1cca5659c85e7c536f5016a2c75c615e65dba75 Mon Sep 17 00:00:00 2001 > From: Qing Zhao <qing.z...@oracle.com> > Date: Fri, 28 Jan 2022 16:29:51 +0000 > Subject: [PATCH] middle-end: updating the reg use in exit block for > -fzero-call-used-regs [PR100775] > > In the pass_zero_call_used_regs, when updating dataflow info after adding > the register zeroing sequence in the epilogue of the function, we should > call "df_update_exit_block_uses" to update the register use information in > the exit block to include all the registers that have been zeroed. > > 2022-01-27 Qing Zhao <qing.z...@oracle.com> > > gcc/ChangeLog: > > * function.cc (gen_call_used_regs_seq): Call > df_update_exit_block_uses when updating df. > > gcc/testsuite/ChangeLog: > > * gcc.target/arm/pr100775.c: New test. > --- > gcc/function.cc | 1 + > gcc/testsuite/gcc.target/arm/pr100775.c | 8 ++++++++ > 2 files changed, 9 insertions(+) > create mode 100644 gcc/testsuite/gcc.target/arm/pr100775.c > > diff --git a/gcc/function.cc b/gcc/function.cc > index e1d2565f8d92..c8a77c9a6246 100644 > --- a/gcc/function.cc > +++ b/gcc/function.cc > @@ -5942,6 +5942,7 @@ gen_call_used_regs_seq (rtx_insn *ret, unsigned int > zero_regs_type) > /* Update the data flow information. */ > crtl->must_be_zero_on_return |= zeroed_hardregs; > df_set_bb_dirty (EXIT_BLOCK_PTR_FOR_FN (cfun)); > + df_update_exit_block_uses (); > } > } > > diff --git a/gcc/testsuite/gcc.target/arm/pr100775.c > b/gcc/testsuite/gcc.target/arm/pr100775.c > new file mode 100644 > index 000000000000..dd2255a95492 > --- /dev/null > +++ b/gcc/testsuite/gcc.target/arm/pr100775.c > @@ -0,0 +1,8 @@ > +/* { dg-do compile } */ > +/* { dg-options "-mthumb -fzero-call-used-regs=used" } */ > + > +int > +foo (int x) > +{ > + return x; > +} > -- > 2.27.0 > > > > >
