On Tue, 6 Dec 2022 at 00:08, Richard Sandiford
<richard.sandiford@arm.com> wrote:
>
> Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org> writes:
> > Hi,
> > The following test:
> >
> > #include "arm_sve.h"
> >
> > svint8_t
> > test_s8(int8_t *x)
> > {
> >   return svld1rq_s8 (svptrue_b8 (), &x[0]);
> > }
> >
> > ICE's with -march=armv8.2-a+sve -O1 -fno-tree-ccp -fno-tree-forwprop:
> > during GIMPLE pass: fre
> > pr107920.c: In function ‘test_s8’:
> > pr107920.c:7:1: internal compiler error: in execute_todo, at passes.cc:2140
> >     7 | }
> >       | ^
> > 0x7b03d0 execute_todo
> >         ../../gcc/gcc/passes.cc:2140
> >
> > because of incorrect handling of virtual operands in svld1rq_impl::fold:
> >  # VUSE <.MEM>
> >   _5 = MEM <vector(16) signed char> [(signed char * {ref-all})x_3(D)];
> >   _4 = VEC_PERM_EXPR <_5, _5, { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
> > 12, 13, 14, 15, ... }>;
> >   # VUSE <.MEM_2(D)>
> >   return _4;
> >
> > The attached patch tries to fix the issue by building the replacement
> > statements in gimple_seq, and passing it to gsi_replace_with_seq_vops,
> > which resolves the ICE, and results in:
> >   <bb 2> :
> >   # VUSE <.MEM_2(D)>
> >   _5 = MEM <vector(16) signed char> [(signed char * {ref-all})x_3(D)];
> >   _4 = VEC_PERM_EXPR <_5, _5, { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
> > 12, 13, 14, 15, ... }>;
> >   # VUSE <.MEM_2(D)>
> >   return _4;
> >
> > Bootstrapped+tested on aarch64-linux-gnu.
> > OK to commit ?
>
> Looks good, but we also need to deal with the -fnon-call-exceptions
> point that Andrew made in the PR trail.  An easy way of testing
> would be to make sure that:
>
> #include "arm_sve.h"
>
> svint8_t
> test_s8(int8_t *x)
> {
>   try
>     {
>       return svld1rq_s8 (svptrue_b8 (), &x[0]);
>     }
>   catch (...)
>     {
>       return svdup_s8 (1);
>     }
> }
>
> compiled with -fnon-call-exceptions still has a call to __cxa_begin_catch.
>
> I don't think it's worth optimising this case.  Let's just add
> !flag_non_call_exceptions to the test.
>
> The patch is missing a changelog btw.
Thanks for the suggestions. Is the attached patch OK to commit after
bootstrap+test ?

Thanks,
Prathamesh
>
> Thanks,
> Richard
>
> > Thanks,
> > Prathamesh
> >
> > diff --git a/gcc/config/aarch64/aarch64-sve-builtins-base.cc b/gcc/config/aarch64/aarch64-sve-builtins-base.cc
> > index 6347407555f..f5546a65d22 100644
> > --- a/gcc/config/aarch64/aarch64-sve-builtins-base.cc
> > +++ b/gcc/config/aarch64/aarch64-sve-builtins-base.cc
> > @@ -45,6 +45,7 @@
> >  #include "aarch64-sve-builtins-base.h"
> >  #include "aarch64-sve-builtins-functions.h"
> >  #include "ssa.h"
> > +#include "gimple-fold.h"
> >
> >  using namespace aarch64_sve;
> >
> > @@ -1232,7 +1233,9 @@ public:
> >       tree mem_ref_op = fold_build2 (MEM_REF, access_type, arg1, zero);
> >       gimple *mem_ref_stmt
> >         = gimple_build_assign (mem_ref_lhs, mem_ref_op);
> > -     gsi_insert_before (f.gsi, mem_ref_stmt, GSI_SAME_STMT);
> > +
> > +     gimple_seq stmts = NULL;
> > +     gimple_seq_add_stmt_without_update (&stmts, mem_ref_stmt);
> >
> >       int source_nelts = TYPE_VECTOR_SUBPARTS (access_type).to_constant ();
> >       vec_perm_builder sel (lhs_len, source_nelts, 1);
> > @@ -1245,8 +1248,11 @@ public:
> >                                                  indices));
> >       tree mask_type = build_vector_type (ssizetype, lhs_len);
> >       tree mask = vec_perm_indices_to_tree (mask_type, indices);
> > -     return gimple_build_assign (lhs, VEC_PERM_EXPR,
> > -                                 mem_ref_lhs, mem_ref_lhs, mask);
> > +     gimple *g2 = gimple_build_assign (lhs, VEC_PERM_EXPR,
> > +                                       mem_ref_lhs, mem_ref_lhs, mask);
> > +     gimple_seq_add_stmt_without_update (&stmts, g2);
> > +     gsi_replace_with_seq_vops (f.gsi, stmts);
> > +     return g2;
> >        }
> >
> >      return NULL;
> > diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
> > index c2d9c806aee..03cdb2f9f49 100644
> > --- a/gcc/gimple-fold.cc
> > +++ b/gcc/gimple-fold.cc
> > @@ -591,7 +591,7 @@ fold_gimple_assign (gimple_stmt_iterator *si)
> >     If the statement has a lhs the last stmt in the sequence is expected
> >     to assign to that lhs.  */
> >
> > -static void
> > +void
> >  gsi_replace_with_seq_vops (gimple_stmt_iterator *si_p, gimple_seq stmts)
> >  {
> >    gimple *stmt = gsi_stmt (*si_p);
> > diff --git a/gcc/gimple-fold.h b/gcc/gimple-fold.h
> > index 7d29ee9a9a4..87ed4e56d25 100644
> > --- a/gcc/gimple-fold.h
> > +++ b/gcc/gimple-fold.h
> > @@ -63,6 +63,7 @@ extern bool arith_code_with_undefined_signed_overflow (tree_code);
> >  extern gimple_seq rewrite_to_defined_overflow (gimple *, bool = false);
> >  extern void replace_call_with_value (gimple_stmt_iterator *, tree);
> >  extern tree tree_vec_extract (gimple_stmt_iterator *, tree, tree, tree, tree);
> > +extern void gsi_replace_with_seq_vops (gimple_stmt_iterator *, gimple_seq);
> >
> >  /* gimple_build, functionally matching fold_buildN, outputs stmts
> >     int the provided sequence, matching and simplifying them on-the-fly.
> > diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general/pr107920.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/pr107920.c
> > new file mode 100644
> > index 00000000000..11448ed5e68
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/pr107920.c
> > @@ -0,0 +1,10 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O1 -fno-tree-ccp -fno-tree-forwprop" } */
> > +
> > +#include "arm_sve.h"
> > +
> > +svint8_t
> > +test_s8(int8_t *x)
> > +{
> > +  return svld1rq_s8 (svptrue_b8 (), &x[0]);
> > +}