On 2021-07-14 12:40, guojiufu via Gcc-patches wrote:
Updated the patch as below:
Thanks for comments.
gcc/ChangeLog:
2021-07-13 Jiufu Guo <guoji...@linux.ibm.com>
PR target/61837
* config/rs6000/rs6000.c (TARGET_PREFERRED_DOLOOP_MODE): New hook.
(rs6000_preferred_doloop_mode): New hook.
* doc/tm.texi: Regenerate.
* doc/tm.texi.in: Add hook preferred_doloop_mode.
* target.def (preferred_doloop_mode): New hook.
* targhooks.c (default_preferred_doloop_mode): New hook.
* targhooks.h (default_preferred_doloop_mode): New hook.
* tree-ssa-loop-ivopts.c (compute_doloop_base_on_mode): New function.
(add_iv_candidate_for_doloop): Call targetm.preferred_doloop_mode
and compute_doloop_base_on_mode.
gcc/testsuite/ChangeLog:
2021-07-13 Jiufu Guo <guoji...@linux.ibm.com>
PR target/61837
* gcc.target/powerpc/pr61837.c: New test.
---
gcc/config/rs6000/rs6000.c | 11 ++++
gcc/doc/tm.texi | 10 ++++
gcc/doc/tm.texi.in | 2 +
gcc/target.def | 14 +++++
gcc/targhooks.c | 8 +++
gcc/targhooks.h | 1 +
gcc/testsuite/gcc.target/powerpc/pr61837.c | 20 +++++++
gcc/tree-ssa-loop-ivopts.c | 67 +++++++++++++++++++++-
8 files changed, 131 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/powerpc/pr61837.c
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 9a5db63d0ef..3bdf0cb97a3 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -1700,6 +1700,9 @@ static const struct attribute_spec
rs6000_attribute_table[] =
#undef TARGET_DOLOOP_COST_FOR_ADDRESS
#define TARGET_DOLOOP_COST_FOR_ADDRESS 1000000000
+#undef TARGET_PREFERRED_DOLOOP_MODE
+#define TARGET_PREFERRED_DOLOOP_MODE rs6000_preferred_doloop_mode
+
#undef TARGET_ATOMIC_ASSIGN_EXPAND_FENV
#define TARGET_ATOMIC_ASSIGN_EXPAND_FENV
rs6000_atomic_assign_expand_fenv
@@ -27867,6 +27870,14 @@ rs6000_predict_doloop_p (struct loop *loop)
return true;
}
+/* Implement TARGET_PREFERRED_DOLOOP_MODE. */
+
+static machine_mode
+rs6000_preferred_doloop_mode (machine_mode)
+{
+ return word_mode;
+}
+
/* Implement TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P. */
static bool
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 2a41ae5fba1..4fb516169dc 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -11984,6 +11984,16 @@ By default, the RTL loop optimizer does not use
a present doloop pattern for
loops containing function calls or branch on table instructions.
@end deftypefn
+@deftypefn {Target Hook} machine_mode TARGET_PREFERRED_DOLOOP_MODE
(machine_mode @var{mode})
+This hook takes a @var{mode} which is the original mode of doloop IV.
+And if the target prefers other mode for doloop IV, this hook returns
the
+preferred mode.
+For example, on 64bit target, DImode may be preferred than SImode.
+This hook could return the original mode itself if the target prefer to
+keep the original mode.
+The origianl mode and return mode should be MODE_INT.
+@end deftypefn
+
@deftypefn {Target Hook} bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn
*@var{insn})
Take an instruction in @var{insn} and return @code{false} if the
instruction
is not appropriate as a combination of two or more instructions. The
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index f881cdabe9e..38215149a92 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -7917,6 +7917,8 @@ to by @var{ce_info}.
@hook TARGET_INVALID_WITHIN_DOLOOP
+@hook TARGET_PREFERRED_DOLOOP_MODE
+
@hook TARGET_LEGITIMATE_COMBINED_INSN
@hook TARGET_CAN_FOLLOW_JUMP
diff --git a/gcc/target.def b/gcc/target.def
index c009671c583..1b6c9872807 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -4454,6 +4454,20 @@ loops containing function calls or branch on
table instructions.",
const char *, (const rtx_insn *insn),
default_invalid_within_doloop)
+/* Returns the machine mode which the target prefers for doloop IV. */
+DEFHOOK
+(preferred_doloop_mode,
+ "This hook takes a @var{mode} which is the original mode of doloop
IV.\n\
+And if the target prefers another mode for doloop IV, this hook returns
the\n\
+preferred mode.\n\
+For example, on 64bit target, DImode may be preferred than SImode.\n\
+This hook could return the original mode itself if the target prefer
to\n\
+keep the original mode.\n\
+The original mode and return mode should be MODE_INT.",
+ machine_mode,
+ (machine_mode mode),
+ default_preferred_doloop_mode)
+
/* Returns true for a legitimate combined insn. */
DEFHOOK
(legitimate_combined_insn,
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index 44a1facedcf..eb5190910dc 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -660,6 +660,14 @@ default_predict_doloop_p (class loop *loop
ATTRIBUTE_UNUSED)
return false;
}
+/* By default, just use the input MODE itself. */
+
+machine_mode
+default_preferred_doloop_mode (machine_mode mode)
+{
+ return mode;
+}
+
/* NULL if INSN insn is valid within a low-overhead loop, otherwise
returns
an error message.
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index f70a307d26c..f92e102c450 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -88,6 +88,7 @@ extern bool default_fixed_point_supported_p (void);
extern bool default_has_ifunc_p (void);
extern bool default_predict_doloop_p (class loop *);
+extern machine_mode default_preferred_doloop_mode (machine_mode);
extern const char * default_invalid_within_doloop (const rtx_insn *);
extern tree default_builtin_vectorized_function (unsigned int, tree,
tree);
diff --git a/gcc/testsuite/gcc.target/powerpc/pr61837.c
b/gcc/testsuite/gcc.target/powerpc/pr61837.c
new file mode 100644
index 00000000000..87b69888c7e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr61837.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-loop2_doloop -fno-unroll-loops" } */
+/* The inner loop would use the doloop IV in word_mode. And then
+ there is no need to access it though zero_extend on shorter mode.
*/
+void foo(int *p1, long *p2, int s)
+{
+ int n, v, i;
+
+ v = 0;
+ for (n = 0; n <= 100; n++) {
+ for (i = 0; i < s; i++)
+ if (p2[i] == n)
+ p1[i] = v;
+ v += 88;
+ }
+}
+
+/* { dg-final {scan-rtl-dump-not "zero_extend.*doloop" "loop2_doloop"}
} */
+/* { dg-final {scan-rtl-dump-not "reg:SI.*doloop" "loop2_doloop" {
target lp64 } } } */
+
diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c
index 12a8a49a307..33da3184d6f 100644
--- a/gcc/tree-ssa-loop-ivopts.c
+++ b/gcc/tree-ssa-loop-ivopts.c
@@ -5657,6 +5657,57 @@ relate_compare_use_with_all_cands (struct
ivopts_data *data)
}
}
+/* If PREFERRED_MODE is suitable and profitable, use the
+ PREFERRED_MODE to compute doloop iv base from niter: base = niter +
1. */
+
+static tree
+compute_doloop_base_on_mode (machine_mode preferred_mode, tree niter,
+ const widest_int &iterations_max)
+{
+ tree ntype = TREE_TYPE (niter);
+ gcc_assert (TYPE_UNSIGNED (ntype));
+
+ tree pref_type = lang_hooks.types.type_for_mode (preferred_mode, 1);
+ gcc_assert (pref_type && TREE_CODE (pref_type) == INTEGER_TYPE);
+
+ int prec = TYPE_PRECISION (ntype);
+ int pref_prec = TYPE_PRECISION (pref_type);
+
+ tree base;
+
+ /* Check if the PREFERRED_MODED is able to present niter. */
+ if (pref_prec > prec
+ || wi::ltu_p (iterations_max,
+ widest_int::from (wi::max_value (pref_prec, UNSIGNED),
+ UNSIGNED)))
+ {
+ /* No wrap, it is safe to use preferred type after niter + 1. */
+ if (wi::ltu_p (iterations_max,
+ widest_int::from (wi::max_value (prec, UNSIGNED),
+ UNSIGNED)))
+ {
+ /* This could help to optimize "-1 +1" pair when niter looks
+ like "n-1": n is in original mode. "base = (n - 1) + 1"
+ in PREFERRED_MODED: it could be base = (PREFERRED_TYPE)n. */
+ base = fold_build2 (PLUS_EXPR, ntype, unshare_expr (niter),
+ build_int_cst (ntype, 1));
+ base = fold_convert (pref_type, base);
+ }
+
+ /* To avoid wrap, need fold niter to preferred type before plus
1. */
+ else
+ {
+ niter = fold_convert (pref_type, niter);
+ base = fold_build2 (PLUS_EXPR, pref_type, unshare_expr (niter),
+ build_int_cst (pref_type, 1));
+ }
+ }
+ else
+ base = fold_build2 (PLUS_EXPR, ntype, unshare_expr (niter),
+ build_int_cst (ntype, 1));
+ return base;
+}
+
/* Add one doloop dedicated IV candidate:
- Base is (may_be_zero ? 1 : (niter + 1)).
- Step is -1. */
@@ -5688,8 +5739,20 @@ add_iv_candidate_for_doloop (struct ivopts_data
*data)
return;
}
- tree base = fold_build2 (PLUS_EXPR, ntype, unshare_expr (niter),
- build_int_cst (ntype, 1));
+ machine_mode mode = TYPE_MODE (ntype);
+ machine_mode pref_mode = targetm.preferred_doloop_mode (mode);
+
+ tree base;
+ if (mode != pref_mode)
+ {
+ base = compute_doloop_base_on_mode (pref_mode, niter,
niter_desc->max);
+ ntype = TREE_TYPE (base);
+ }
+ else
+ base = fold_build2 (PLUS_EXPR, ntype, unshare_expr (niter),
+ build_int_cst (ntype, 1));
+
+
add_candidate (data, base, build_int_cst (ntype, -1), true, NULL,
NULL, true);
}
--
2.17.1
On 2021-07-14 04:50, Segher Boessenkool wrote:
Hi!
On Tue, Jul 13, 2021 at 08:50:46PM +0800, Jiufu Guo wrote:
* doc/tm.texi: Regenerated.
Pet peeve: "Regenerate.", no "d".
Ok, yeap. While, 'Regenerate and Regenerated' were used by commits
somewhere :)
+DEFHOOK
+(preferred_doloop_mode,
+ "This hook returns a more preferred mode or the @var{mode}
itself.",
+ machine_mode,
+ (machine_mode mode),
+ default_preferred_doloop_mode)
You need a bit more description here. What does the value it returns
mean? If you want to say "a more preferred mode or the mode itself",
you should explain what the difference means, too.
Ok, thanks.
You also should say the hook does not need to test if things will fit,
since the generic code already does.
And say this should return a MODE_INT always -- you never test for
that
as far as I can see, but you don't need to, as long as everyone does
the
sane thing. So just state every hok implementation should :-)
Yes, the preferred 'doloop iv mode' from targets should be a MODE_INT.
I will add comments, and update the gcc_assert you mentioned below
for this.
Thanks a lot for your comments and suggestions!
When writing words, I was always from adding/deleting and still hard to
get
perfect ones -:(
+extern machine_mode
+default_preferred_doloop_mode (machine_mode);
One line please (this is a declaration).
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+void foo(int *p1, long *p2, int s)
+{
+ int n, v, i;
+
+ v = 0;
+ for (n = 0; n <= 100; n++) {
+ for (i = 0; i < s; i++)
+ if (p2[i] == n)
+ p1[i] = v;
+ v += 88;
+ }
+}
+
+/* { dg-final { scan-assembler-not {\mrldicl\M} } } */
That is a pretty fragile thing to test for. It also need a line or
two
of comment in the test case what this does, what kind of thing it does
not want to see.
Thanks! I will update accordingly. And I'm thinking to add tests to
check
doloop.xx type: no zero_extend to access subreg. This is the intention
of this patch.
+/* If PREFERRED_MODE is suitable and profitable, use the preferred
+ PREFERRED_MODE to compute doloop iv base from niter: base = niter
+ 1. */
+
+static tree
+compute_doloop_base_on_mode (machine_mode preferred_mode, tree
niter,
+ const widest_int &iterations_max)
+{
+ tree ntype = TREE_TYPE (niter);
+ tree pref_type = lang_hooks.types.type_for_mode (preferred_mode,
1);
+
+ gcc_assert (pref_type && TYPE_UNSIGNED (ntype));
Should that be pref_type instead of ntype? If not, write it as two
separate asserts please.
Ok, will separate as two asserts.
+static machine_mode
+rs6000_preferred_doloop_mode (machine_mode)
+{
+ return word_mode;
+}
This is fine if the generic code does the right thing if it passes say
TImode here, and if it never will pass some other mode class mode.
The generic code checks if the returned mode can works on doloop iv
correctly,
if the preferred mode is not suitable (e.g. preferred_doloop_mode
returns DI,
but niter is a large value in TI), then doloop.xx IV will use the
original mode.
When a target really prefer TImode, and TImode can represent number of
iterations,
This would still work. In current code, word_mode is SI/DI in most
targets, like Pmode.
On powerpc, they are DImode (for 64bit)/SImode(32bit)
Thanks again for your comments!
BR,
Jiufu
Segher
