i386: Only enable small loop unrolling in backend [PR 107692]
Followed by the discussion in pr107692, -munroll-only-small-loops
Does not turns on/off -funroll-loops, and current check in
pass_rtl_unroll_loops::gate would cause -fno-unroll-loops do not take
effect. Revert the change about targetm.loop_unroll_adjust and apply
the backend option change to strictly follow the rule that
-funroll-loops takes full control of loop unrolling, and
munroll-only-small-loops just change its behavior to unroll small size
loops.
gcc/ChangeLog:
PR target/107692
* common/config/i386/i386-common.cc (ix86_optimization_table):
Enable loop unroll O2, disable -fweb and -frename-registers
by default.
* config/i386/i386-options.cc
(ix86_override_options_after_change):
Disable small loop unroll when funroll-loops enabled, reset
cunroll_grow_size when it is not explicitly enabled.
(ix86_option_override_internal): Call
ix86_override_options_after_change instead of calling
ix86_recompute_optlev_based_flags and ix86_default_align
separately.
* config/i386/i386.cc (ix86_loop_unroll_adjust): Adjust unroll
factor if -munroll-only-small-loops enabled.
* loop-init.cc (pass_rtl_unroll_loops::gate): Do not enable
loop unrolling for -O2-speed.
(pass_rtl_unroll_loops::execute): Rmove
targetm.loop_unroll_adjust check.
gcc/testsuite/ChangeLog:
PR target/107692
* gcc.dg/guality/loop-1.c: Remove additional option for ia32.
* gcc.target/i386/pr86270.c: Add -fno-unroll-loops.
* gcc.target/i386/pr93002.c: Likewise.
diff --git a/gcc/common/config/i386/i386-common.cc b/gcc/common/config/i386/i386-common.cc
index 6ce2a58..660a977 100644
--- a/gcc/common/config/i386/i386-common.cc
+++ b/gcc/common/config/i386/i386-common.cc
@@ -1808,7 +1808,15 @@
/* The STC algorithm produces the smallest code at -Os, for x86. */
{ OPT_LEVELS_2_PLUS, OPT_freorder_blocks_algorithm_, NULL,
REORDER_BLOCKS_ALGORITHM_STC },
+
+ /* Turn on -funroll-loops with -munroll-only-small-loops to enable small
+ loop unrolling at -O2. */
+ { OPT_LEVELS_2_PLUS_SPEED_ONLY, OPT_funroll_loops, NULL, 1 },
{ OPT_LEVELS_2_PLUS_SPEED_ONLY, OPT_munroll_only_small_loops, NULL, 1 },
+ /* Turns off -frename-registers and -fweb which are enabled by
+ funroll-loops. */
+ { OPT_LEVELS_ALL, OPT_frename_registers, NULL, 0 },
+ { OPT_LEVELS_ALL, OPT_fweb, NULL, 0 },
/* Turn off -fschedule-insns by default. It tends to make the
problem with not enough registers even worse. */
{ OPT_LEVELS_ALL, OPT_fschedule_insns, NULL, 0 },
diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc
index e5c77f3..bc1d36e 100644
--- a/gcc/config/i386/i386-options.cc
+++ b/gcc/config/i386/i386-options.cc
@@ -1838,8 +1838,37 @@
void
ix86_override_options_after_change (void)
{
+ /* Default align_* from the processor table. */
ix86_default_align (&global_options);
+
ix86_recompute_optlev_based_flags (&global_options, &global_options_set);
+
+ /* Disable unrolling small loops when there's explicit
+ -f{,no}unroll-loop. */
+ if ((OPTION_SET_P (flag_unroll_loops))
+ || (OPTION_SET_P (flag_unroll_all_loops)
+ && flag_unroll_all_loops))
+ {
+ if (!OPTION_SET_P (ix86_unroll_only_small_loops))
+ ix86_unroll_only_small_loops = 0;
+ /* Re-enable -frename-registers and -fweb if funroll-loops
+ enabled. */
+ if (!OPTION_SET_P (flag_web))
+ flag_web = flag_unroll_loops;
+ if (!OPTION_SET_P (flag_rename_registers))
+ flag_rename_registers = flag_unroll_loops;
+ /* -fcunroll-grow-size default follws -f[no]-unroll-loops. */
+ if (!OPTION_SET_P (flag_cunroll_grow_size))
+ flag_cunroll_grow_size = flag_unroll_loops
+ || flag_peel_loops
+ || optimize >= 3;
+ }
+ else
+ {
+ if (!OPTION_SET_P (flag_cunroll_grow_size))
+ flag_cunroll_grow_size = flag_peel_loops || optimize >= 3;
+ }
+
}
/* Clear stack slot assignments remembered from previous functions.
@@ -2351,7 +2380,7 @@
set_ix86_tune_features (opts, ix86_tune, opts->x_ix86_dump_tunes);
- ix86_recompute_optlev_based_flags (opts, opts_set);
+ ix86_override_options_after_change ();
ix86_tune_cost = processor_cost_table[ix86_tune];
/* TODO: ix86_cost should be chosen at instruction or function granuality
@@ -2382,9 +2411,6 @@
|| TARGET_64BIT_P (opts->x_ix86_isa_flags))
opts->x_ix86_regparm = REGPARM_MAX;
- /* Default align_* from the processor table. */
- ix86_default_align (opts);
-
/* Provide default for -mbranch-cost= value. */
SET_OPTION_IF_UNSET (opts, opts_set, ix86_branch_cost,
ix86_tune_cost->branch_cost);
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 14719d3..881cd9f 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -23828,20 +23828,12 @@
/* Unroll small size loop when unroll factor is not explicitly
specified. */
- if (!(flag_unroll_loops
- || flag_unroll_all_loops
- || loop->unroll))
+ if (ix86_unroll_only_small_loops && !loop->unroll)
{
- nunroll = 1;
-
- /* Any explicit -f{no-}unroll-{all-}loops turns off
- -munroll-only-small-loops. */
- if (ix86_unroll_only_small_loops
- && !OPTION_SET_P (flag_unroll_loops)
- && loop->ninsns <= ix86_cost->small_unroll_ninsns)
- nunroll = ix86_cost->small_unroll_factor;
-
- return nunroll;
+ if (loop->ninsns <= ix86_cost->small_unroll_ninsns)
+ return MIN (nunroll, ix86_cost->small_unroll_factor);
+ else
+ return 1;
}
if (!TARGET_ADJUST_UNROLL)
diff --git a/gcc/loop-init.cc b/gcc/loop-init.cc
index 9789efa..f03c077 100644
--- a/gcc/loop-init.cc
+++ b/gcc/loop-init.cc
@@ -565,12 +565,10 @@
{}
/* opt_pass methods: */
- bool gate (function *fun) final override
+ bool gate (function *) final override
{
- return (flag_unroll_loops || flag_unroll_all_loops || cfun->has_unroll
- || (targetm.loop_unroll_adjust
- && optimize >= 2
- && optimize_function_for_speed_p (fun)));
+ return (flag_unroll_loops || flag_unroll_all_loops
+ || cfun->has_unroll);
}
unsigned int execute (function *) final override;
@@ -586,8 +584,7 @@
if (dump_file)
df_dump (dump_file);
- if (flag_unroll_loops
- || targetm.loop_unroll_adjust)
+ if (flag_unroll_loops)
flags |= UAP_UNROLL;
if (flag_unroll_all_loops)
flags |= UAP_UNROLL_ALL;
diff --git a/gcc/testsuite/gcc.dg/guality/loop-1.c b/gcc/testsuite/gcc.dg/guality/loop-1.c
index a32ea44..1b1f6d3 100644
--- a/gcc/testsuite/gcc.dg/guality/loop-1.c
+++ b/gcc/testsuite/gcc.dg/guality/loop-1.c
@@ -1,7 +1,5 @@
/* { dg-do run } */
/* { dg-options "-fno-tree-scev-cprop -fno-tree-vectorize -g" } */
-/* { dg-additional-options "-mno-unroll-only-small-loops" { target ia32 } } */
-
#include "../nop.h"
diff --git a/gcc/testsuite/gcc.target/i386/pr86270.c b/gcc/testsuite/gcc.target/i386/pr86270.c
index cbc9fbb..98b012c 100644
--- a/gcc/testsuite/gcc.target/i386/pr86270.c
+++ b/gcc/testsuite/gcc.target/i386/pr86270.c
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O2 -mno-unroll-only-small-loops" } */
+/* { dg-options "-O2 -fno-unroll-loops" } */
int *a;
long len;
diff --git a/gcc/testsuite/gcc.target/i386/pr93002.c b/gcc/testsuite/gcc.target/i386/pr93002.c
index f75a847..7e2d869 100644
--- a/gcc/testsuite/gcc.target/i386/pr93002.c
+++ b/gcc/testsuite/gcc.target/i386/pr93002.c
@@ -1,6 +1,6 @@
/* PR target/93002 */
/* { dg-do compile } */
-/* { dg-options "-O2 -mno-unroll-only-small-loops" } */
+/* { dg-options "-O2 -fno-unroll-loops" } */
/* { dg-final { scan-assembler-not "cmp\[^\n\r]*-1" } } */
volatile int sink;
