RFC: Add ADDR_EXPR lowering (PR tree-optimization/66718)
Richard Biener
rguenther@suse.de
Thu Jul 9 08:53:00 GMT 2015
On Wed, 8 Jul 2015, Marek Polacek wrote:
> On Fri, Jul 03, 2015 at 03:41:29PM +0200, Richard Biener wrote:
> > On Fri, 3 Jul 2015, Marek Polacek wrote:
> >
> > > This patch implements a new pass, called laddress, which deals with
> > > lowering ADDR_EXPR assignments. Such lowering ought to help the
> > > vectorizer, but it also could expose more CSE opportunities, maybe
> > > help reassoc, etc. It's only active when optimize != 0.
> > >
> > > So e.g.
> > > _1 = (sizetype) i_9;
> > > _7 = _1 * 4;
> > > _4 = &b + _7;
> > > instead of
> > > _4 = &b[i_9];
> > >
> > > This triggered 14105 times during the regtest and 6392 times during
> > > the bootstrap.
> > >
> > > The fallout (at least on x86_64) is surprisingly small, i.e. none, just
> > > gcc.dg/vect/pr59984.c test (using -fopenmp-simd) ICEs, but that is due
> > > to a bug in the vectorizer. Jakub has a patch and knows the details.
> > > As the test shows, we're now able to vectorize ADDR_EXPR of non-invariants
> > > (that was the motivation of this pass).
> > >
> > > This doesn't introduce any kind of verification nor PROP_laddress.
> > > Don't know if we want that, but hopefully it can be done as a follow-up
> > > if we do.
> >
> > Yes. At the moment nothing requires lowered address form so this is
> > merely an optimization (and not a bug for some later pass to
> > re-introduce un-lowered non-invariant addresses). I can imagine
> > that for example IVOPTs could be simplified if we didn't have this
> > kind of addresses in the IL.
> >
> > > Do we want to move some optimizations into this new pass, e.g.
> > > from fwprop?
> >
> > I think we might want to re-try forwprop_into_addr_expr before lowering
> > the address. Well, but that's maybe just over-cautionous.
> >
> > > Thoughts?
> >
> > Please move the pass before crited, crited and pre are supposed to
> > go together.
>
> Done.
>
> > Otherwise looks ok to me.
>
> I renamed the file to gimple-laddress.c then and adjusted the timevar.
> Another change is that for x86_64 we don't need -mavx at all, so I dropped
> that. The test is now restricted to x86_64/i?86; on aarch64/ppc64 we aren't
> able to vectorize all the functions.
>
> Bootstrapped/regtested on x86_64-linux + ppc64-linux, ok for trunk?
Ok.
Thanks,
Richard.
> 2015-07-08 Marek Polacek <polacek@redhat.com>
>
> PR tree-optimization/66718
> * Makefile.in (OBJS): Add gimple-laddress.o.
> * passes.def: Schedule pass_laddress.
> * timevar.def (DEFTIMEVAR): Add TV_GIMPLE_LADDRESS.
> * tree-pass.h (make_pass_laddress): Declare.
> * gimple-laddress.c: New file.
>
> * gcc.dg/vect/vect-126.c: New test.
>
> diff --git gcc/Makefile.in gcc/Makefile.in
> index 89eda96..1817025 100644
> --- gcc/Makefile.in
> +++ gcc/Makefile.in
> @@ -1255,6 +1255,7 @@ OBJS = \
> gimple-expr.o \
> gimple-iterator.o \
> gimple-fold.o \
> + gimple-laddress.o \
> gimple-low.o \
> gimple-match.o \
> generic-match.o \
> diff --git gcc/gimple-laddress.c gcc/gimple-laddress.c
> index e69de29..c8036b9 100644
> --- gcc/gimple-laddress.c
> +++ gcc/gimple-laddress.c
> @@ -0,0 +1,137 @@
> +/* Lower and optimize address expressions.
> + Copyright (C) 2015 Free Software Foundation, Inc.
> + Contributed by Marek Polacek <polacek@redhat.com>
> +
> +This file is part of GCC.
> +
> +GCC is free software; you can redistribute it and/or modify it under
> +the terms of the GNU General Public License as published by the Free
> +Software Foundation; either version 3, or (at your option) any later
> +version.
> +
> +GCC is distributed in the hope that it will be useful, but WITHOUT ANY
> +WARRANTY; without even the implied warranty of MERCHANTABILITY or
> +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
> +for more details.
> +
> +You should have received a copy of the GNU General Public License
> +along with GCC; see the file COPYING3. If not see
> +<http://www.gnu.org/licenses/>. */
> +
> +#include "config.h"
> +#include "system.h"
> +#include "coretypes.h"
> +#include "alias.h"
> +#include "predict.h"
> +#include "tm.h"
> +#include "function.h"
> +#include "dominance.h"
> +#include "cfg.h"
> +#include "basic-block.h"
> +#include "tree-ssa-alias.h"
> +#include "symtab.h"
> +#include "tree.h"
> +#include "stringpool.h"
> +#include "tree-ssanames.h"
> +#include "fold-const.h"
> +#include "gimple-expr.h"
> +#include "gimple.h"
> +#include "gimplify.h"
> +#include "gimple-iterator.h"
> +#include "gimplify-me.h"
> +#include "tree-pass.h"
> +
> +
> +namespace {
> +
> +const pass_data pass_data_laddress =
> +{
> + GIMPLE_PASS, /* type */
> + "laddress", /* name */
> + OPTGROUP_NONE, /* optinfo_flags */
> + TV_GIMPLE_LADDRESS, /* tv_id */
> + ( PROP_cfg | PROP_ssa ), /* properties_required */
> + 0, /* properties_provided */
> + 0, /* properties_destroyed */
> + 0, /* todo_flags_start */
> + 0, /* todo_flags_finish */
> +};
> +
> +class pass_laddress : public gimple_opt_pass
> +{
> +public:
> + pass_laddress (gcc::context *ctxt)
> + : gimple_opt_pass (pass_data_laddress, ctxt)
> + {}
> +
> + /* opt_pass methods: */
> + opt_pass * clone () { return new pass_laddress (m_ctxt); }
> + virtual bool gate (function *) { return optimize != 0; }
> + virtual unsigned int execute (function *);
> +
> +}; // class pass_laddress
> +
> +unsigned int
> +pass_laddress::execute (function *fun)
> +{
> + basic_block bb;
> +
> + FOR_EACH_BB_FN (bb, fun)
> + {
> + for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
> + {
> + gimple stmt = gsi_stmt (gsi);
> + if (!is_gimple_assign (stmt)
> + || gimple_assign_rhs_code (stmt) != ADDR_EXPR
> + || is_gimple_invariant_address (gimple_assign_rhs1 (stmt)))
> + {
> + gsi_next (&gsi);
> + continue;
> + }
> +
> + /* Lower ADDR_EXPR assignments:
> + _4 = &b[i_9];
> + into
> + _1 = (sizetype) i_9;
> + _7 = _1 * 4;
> + _4 = &b + _7;
> + This ought to aid the vectorizer and expose CSE opportunities.
> + */
> +
> + tree expr = gimple_assign_rhs1 (stmt);
> + HOST_WIDE_INT bitsize, bitpos;
> + tree base, offset;
> + machine_mode mode;
> + int volatilep = 0, unsignedp = 0;
> + base = get_inner_reference (TREE_OPERAND (expr, 0), &bitsize,
> + &bitpos, &offset, &mode, &unsignedp,
> + &volatilep, false);
> + gcc_assert (base != NULL_TREE && (bitpos % BITS_PER_UNIT) == 0);
> + if (offset != NULL_TREE)
> + {
> + if (bitpos != 0)
> + offset = size_binop (PLUS_EXPR, offset,
> + size_int (bitpos / BITS_PER_UNIT));
> + offset = force_gimple_operand_gsi (&gsi, offset, true, NULL,
> + true, GSI_SAME_STMT);
> + base = build_fold_addr_expr (base);
> + base = force_gimple_operand_gsi (&gsi, base, true, NULL,
> + true, GSI_SAME_STMT);
> + gimple g = gimple_build_assign (gimple_assign_lhs (stmt),
> + POINTER_PLUS_EXPR, base, offset);
> + gsi_replace (&gsi, g, false);
> + }
> + gsi_next (&gsi);
> + }
> + }
> +
> + return 0;
> +}
> +
> +} // anon namespace
> +
> +gimple_opt_pass *
> +make_pass_laddress (gcc::context *ctxt)
> +{
> + return new pass_laddress (ctxt);
> +}
> diff --git gcc/passes.def gcc/passes.def
> index 0d8356b..5cd07ae 100644
> --- gcc/passes.def
> +++ gcc/passes.def
> @@ -213,6 +213,7 @@ along with GCC; see the file COPYING3. If not see
> form if possible. */
> NEXT_PASS (pass_cse_sincos);
> NEXT_PASS (pass_optimize_bswap);
> + NEXT_PASS (pass_laddress);
> NEXT_PASS (pass_split_crit_edges);
> NEXT_PASS (pass_pre);
> NEXT_PASS (pass_sink_code);
> diff --git gcc/testsuite/gcc.dg/vect/vect-126.c gcc/testsuite/gcc.dg/vect/vect-126.c
> index e69de29..e269ad3 100644
> --- gcc/testsuite/gcc.dg/vect/vect-126.c
> +++ gcc/testsuite/gcc.dg/vect/vect-126.c
> @@ -0,0 +1,63 @@
> +/* PR tree-optimization/66718 */
> +/* { dg-do compile } */
> +
> +int *a[1024], b[1024];
> +struct S { int u, v, w, x; };
> +struct S c[1024];
> +int d[1024][10];
> +
> +void
> +f0 (void)
> +{
> + for (int i = 0; i < 1024; i++)
> + a[i] = &b[0];
> +}
> +
> +void
> +f1 (void)
> +{
> + for (int i = 0; i < 1024; i++)
> + {
> + int *p = &b[0];
> + a[i] = p + i;
> + }
> +}
> +
> +void
> +f2 (int *p)
> +{
> + for (int i = 0; i < 1024; i++)
> + a[i] = &p[i];
> +}
> +
> +void
> +f3 (void)
> +{
> + for (int i = 0; i < 1024; i++)
> + a[i] = &b[i];
> +}
> +
> +void
> +f4 (void)
> +{
> + int *p = &c[0].v;
> + for (int i = 0; i < 1024; i++)
> + a[i] = &p[4 * i];
> +}
> +
> +void
> +f5 (void)
> +{
> + for (int i = 0; i < 1024; i++)
> + a[i] = &c[i].v;
> +}
> +
> +void
> +f6 (void)
> +{
> + for (int i = 0; i < 1024; i++)
> + for (unsigned int j = 0; j < 10; j++)
> + a[i] = &d[i][j];
> +}
> +
> +/* { dg-final { scan-tree-dump-times "vectorized 1 loops in function" 7 "vect" { target { i?86-*-* x86_64-*-* } } } } */
> diff --git gcc/timevar.def gcc/timevar.def
> index efac4b7..ff22909 100644
> --- gcc/timevar.def
> +++ gcc/timevar.def
> @@ -275,6 +275,7 @@ DEFTIMEVAR (TV_GIMPLE_SLSR , "straight-line strength reduction")
> DEFTIMEVAR (TV_VTABLE_VERIFICATION , "vtable verification")
> DEFTIMEVAR (TV_TREE_UBSAN , "tree ubsan")
> DEFTIMEVAR (TV_INITIALIZE_RTL , "initialize rtl")
> +DEFTIMEVAR (TV_GIMPLE_LADDRESS , "address lowering")
>
> /* Everything else in rest_of_compilation not included above. */
> DEFTIMEVAR (TV_EARLY_LOCAL , "early local passes")
> diff --git gcc/tree-pass.h gcc/tree-pass.h
> index 2808dad..c47b22e 100644
> --- gcc/tree-pass.h
> +++ gcc/tree-pass.h
> @@ -393,6 +393,7 @@ extern gimple_opt_pass *make_pass_cd_dce (gcc::context *ctxt);
> extern gimple_opt_pass *make_pass_call_cdce (gcc::context *ctxt);
> extern gimple_opt_pass *make_pass_merge_phi (gcc::context *ctxt);
> extern gimple_opt_pass *make_pass_split_crit_edges (gcc::context *ctxt);
> +extern gimple_opt_pass *make_pass_laddress (gcc::context *ctxt);
> extern gimple_opt_pass *make_pass_pre (gcc::context *ctxt);
> extern unsigned int tail_merge_optimize (unsigned int);
> extern gimple_opt_pass *make_pass_profile (gcc::context *ctxt);
>
> Marek
>
>
--
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Dilip Upmanyu, Graham Norton, HRB 21284 (AG Nuernberg)
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