On 2020-11-02 6:43 a.m., Segher Boessenkool wrote:
Hi!
On Sun, Nov 01, 2020 at 06:32:02PM -0500, Vladimir Makarov wrote:
On 2020-10-30 7:36 p.m., Segher Boessenkool wrote:
Thanks for the patch! But it has a problem:
diff --git a/gcc/config/rs6000/vsx.md b/gcc/config/rs6000/vsx.md
index 67e4f2fd037..78de85ccbbb 100644
--- a/gcc/config/rs6000/vsx.md
+++ b/gcc/config/rs6000/vsx.md
@@ -3717,7 +3717,7 @@
(vec_select:<VS_scalar>
(match_operand:VSX_EXTRACT_I 1 "gpc_reg_operand" "<VSX_EX>,v")
(parallel [(match_operand:QI 2 "const_int_operand" "n,n")])))
- (clobber (match_scratch:<VS_scalar> 3 "=<VSX_EX>,&r"))
+ (clobber (match_scratch:<VS_scalar> 3 "=*<VSX_EX>,&*r"))
(clobber (match_scratch:SI 4 "=X,&r"))]
"VECTOR_MEM_VSX_P (<MODE>mode) && TARGET_VEXTRACTUB"
"#"
You add * to both alternatives here? I would expect adding it to only
the second alternative, does it work better with both?
No. It works the same. When the both alternatives use the hint, the
scratch pseudo got the class ALL_REGS. When only the 2nd use the hint,
the class is VSX_REGS. As I understand now the preferable alternative
is the 1st one (with <VSX> for the scratch). In this case using the
hint only for the 2nd alternative has more sense.
That also avoids a different problem: *<VSX_EX> won't work as expected.
'*' in IRA skips one constraint character, but <VSX_EX> can be "wa", a
two-letter constraint (and we do have an "a" constraint as well,
something wholly different: "wa" means a VSX register, while "a" is an
indexed address).
case '*':
/* Ignore the next letter for this pass. */
c = *++p;
break;
I see. Thanks for pointing this out. Definitely it is better to use the
hint only for the second alternative ("&*r") then. Is this solution ok
for you?
Yes, certainly. And thanks!
I've just committed the following patch
commit 1c689b827c6a0a5e164f22865696a94e6d7ec308 (HEAD -> master,
origin/master, origin/HEAD)
Author: Vladimir N. Makarov <vmaka...@redhat.com>
Date: Mon Nov 2 11:03:54 2020 -0500
Add hint * too 2nd alternative of the 1st scratch in
*vsx_extract_<mode>_store_p9.
gcc/ChangeLog:
* config/rs6000/vsx.md (*vsx_extract_<mode>_store_p9): Add
hint *
to 2nd alternative of the 1st scratch.
diff --git a/gcc/config/rs6000/vsx.md b/gcc/config/rs6000/vsx.md
index 67e4f2fd037..947631d83ee 100644
--- a/gcc/config/rs6000/vsx.md
+++ b/gcc/config/rs6000/vsx.md
@@ -3717,7 +3717,7 @@
(vec_select:<VS_scalar>
(match_operand:VSX_EXTRACT_I 1 "gpc_reg_operand" "<VSX_EX>,v")
(parallel [(match_operand:QI 2 "const_int_operand" "n,n")])))
- (clobber (match_scratch:<VS_scalar> 3 "=<VSX_EX>,&r"))
+ (clobber (match_scratch:<VS_scalar> 3 "=<VSX_EX>,&*r"))
(clobber (match_scratch:SI 4 "=X,&r"))]
"VECTOR_MEM_VSX_P (<MODE>mode) && TARGET_VEXTRACTUB"
"#"
(Should "*" be changed so that it skips a whole constraint if it can,
instead of only a single char always?)
Yes, it should be changed. I believe this is a leftover from the time
when all constraints were just one character. All hints (modifiers)
should work on constraint base not the character one.
