| Message ID | CAFULd4asYbD30GODKEYOUyoCH3mKRtm+zbXEW0+nK8O=6wZ7hw@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On Sun, Jan 06, 2013 at 04:48:03PM +0100, Uros Bizjak wrote: > --- df-problems.c (revision 194945) > +++ df-problems.c (working copy) > @@ -3916,6 +3916,10 @@ can_move_insns_across (rtx from, rtx to, rtx acros > break; > if (NONDEBUG_INSN_P (insn)) > { > + /* Do not move unspec_volatile insns. */ > + if (GET_CODE (PATTERN (insn)) == UNSPEC_VOLATILE) > + break; > + Shouldn't UNSPEC_VOLATILE be handled similarly in the across_from .. across_to loop? Both UNSPEC_VOLATILE and volatile asm are handled there just with trapping_insns_in_across |= may_trap_p (PATTERN (insn)); but your new change doesn't prevent moving just trapping insns across UNSPEC_VOLATILE, but any insns whatsoever. So supposedly for UNSPEC_VOLATILE the first loop should just return false; (or fail = 1; ?). For asm volatile I guess the code is fine as is, it must always describe what exactly it modifies, so supposedly non-trapping insns can be moved across asm volatile. > if (may_trap_or_fault_p (PATTERN (insn)) > && (trapping_insns_in_across || other_branch_live != NULL)) > break; You could do the check only for may_trap_or_fault_p, all UNSPEC_VOLATILE may trap. BTW, can't UNSPEC_VOLATILE be embedded deeply in the pattern? So volatile_insn_p (insn) && asm_noperands (PATTERN (insn)) == -1? But perhaps you want to treat that way only UNSPEC_VOLATILE directly in the pattern and all other UNSPEC_VOLATILE insns must describe in detail what exactly they are changing? This really needs to be better documented. Jakub
On Sun, Jan 6, 2013 at 5:22 PM, Jakub Jelinek <jakub@redhat.com> wrote: >> --- df-problems.c (revision 194945) >> +++ df-problems.c (working copy) >> @@ -3916,6 +3916,10 @@ can_move_insns_across (rtx from, rtx to, rtx acros >> break; >> if (NONDEBUG_INSN_P (insn)) >> { >> + /* Do not move unspec_volatile insns. */ >> + if (GET_CODE (PATTERN (insn)) == UNSPEC_VOLATILE) >> + break; >> + > > Shouldn't UNSPEC_VOLATILE be handled similarly in the across_from .. > across_to loop? Both UNSPEC_VOLATILE and volatile asm are handled there > just with > trapping_insns_in_across |= may_trap_p (PATTERN (insn)); > but your new change doesn't prevent moving just trapping insns across > UNSPEC_VOLATILE, but any insns whatsoever. So supposedly for UNSPEC_VOLATILE > the first loop should just return false; (or fail = 1; ?). > For asm volatile I guess the code is fine as is, it must always describe > what exactly it modifies, so supposedly non-trapping insns can be moved > across asm volatile. > >> if (may_trap_or_fault_p (PATTERN (insn)) >> && (trapping_insns_in_across || other_branch_live != NULL)) >> break; > > You could do the check only for may_trap_or_fault_p, all UNSPEC_VOLATILE > may trap. > > BTW, can't UNSPEC_VOLATILE be embedded deeply in the pattern? > So volatile_insn_p (insn) && asm_noperands (PATTERN (insn)) == -1? > But perhaps you want to treat that way only UNSPEC_VOLATILE directly in the > pattern and all other UNSPEC_VOLATILE insns must describe in detail what > exactly they are changing? This really needs to be better documented. TBH, I'm not that familiar with the RTL infrastructure enough to answer these questions. While I can spend some time on this problem, and probably waste quite some reviewer's time, the problem is not that trivial as I hoped to be, so I would kindly ask someone with better understanding of this part of the compiler for the proper solution. Uros.
Index: df-problems.c =================================================================== --- df-problems.c (revision 194945) +++ df-problems.c (working copy) @@ -3916,6 +3916,10 @@ can_move_insns_across (rtx from, rtx to, rtx acros break; if (NONDEBUG_INSN_P (insn)) { + /* Do not move unspec_volatile insns. */ + if (GET_CODE (PATTERN (insn)) == UNSPEC_VOLATILE) + break; + if (may_trap_or_fault_p (PATTERN (insn)) && (trapping_insns_in_across || other_branch_live != NULL)) break; Index: testsuite/gcc.target/i386/pr55845.c =================================================================== --- testsuite/gcc.target/i386/pr55845.c (revision 0) +++ testsuite/gcc.target/i386/pr55845.c (working copy) @@ -0,0 +1,39 @@ +/* { dg-do run } */ +/* { dg-require-effective-target avx } */ +/* { dg-options "-O3 -ffast-math -fschedule-insns -mavx -mvzeroupper" } */ + +#include "avx-check.h" + +#define N 100 + +double +__attribute__((noinline)) +foo (int size, double y[], double x[]) +{ + double sum = 0.0; + int i; + for (i = 0, sum = 0.; i < size; i++) + sum += y[i] * x[i]; + return (sum); +} + +static void +__attribute__ ((noinline)) +avx_test () +{ + double x[N]; + double y[N]; + double s; + int i; + + for (i = 0; i < N; i++) + { + x[i] = i; + y[i] = i; + } + + s = foo (N, y, x); + + if (s != 328350.0) + abort (); +}
Hello! Attached patch fixes runtime comparison failure of 454.calculix due to wrong movement of vzeroupper in jump2 pass. It turns out, that can_move_insns_accross function does not special-case unspec_volatiles, so vzeroupper is allowed to pass various 256bit avx instructions. The patch rejects moves of unspec_volatile insns in can_move_insn_accross. 2012-01-06 Uros Bizjak <ubizjak@gmail.com> PR rtl-optimization/55845 * df-problems.c (can_move_insns_across): Stop scanning at unspec_volatile source instruction. 2012-01-06 Uros Bizjak <ubizjak@gmail.com> Vladimir Yakovlev <vladimir.b.yakovlev@intel.com> PR rtl-optimization/55845 * gcc.target/i386/pr55845.c: New test. Bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32} AVX target. OK for mainline and 4.7 branch? Uros.