* [PATCH] Restore RTL alias analysis for hard frame pointer
@ 2022-10-28 9:10 Eric Botcazou
2022-10-28 12:27 ` Richard Biener
0 siblings, 1 reply; 7+ messages in thread
From: Eric Botcazou @ 2022-10-28 9:10 UTC (permalink / raw)
To: gcc-patches
[-- Attachment #1: Type: text/plain, Size: 1171 bytes --]
Hi,
the following change:
2021-07-28 Bin Cheng <bin.cheng@linux.alibaba.com>
* alias.c (init_alias_analysis): Don't skip prologue/epilogue.
broke the alias analysis for the hard frame pointer (when it is used as a
frame pointer, i.e. when the frame pointer is not eliminated) described in the
large comment at the top of the file, because static_reg_base_value is set for
it and, consequently, new_reg_base_value too. So when the instruction saving
the stack pointer into the hard frame pointer in the prologue is processed, it
is viewed as a second set of the hard frame pointer and to a different value
by record_set, which then resets new_reg_base_value to 0 and the game is over.
This e.g. hampers the performance of the var-tracking RTL pass for parameters
passed on the stack like on x86, leading to regressions when debugging, but
code generation is very likely affected too.
Bootstrapped/regtested on x86-64/Linux, OK for mainline and 12 branch?
2022-10-28 Eric Botcazou <ebotcazou@adacore.com>
* alias.cc (init_alias_analysis): Do not record sets to the hard
frame pointer if the frame pointer has not been eliminated.
--
Eric Botcazou
[-- Attachment #2: p.diff --]
[-- Type: text/x-patch, Size: 1803 bytes --]
diff --git a/gcc/alias.cc b/gcc/alias.cc
index d54feb15268..c62837dd854 100644
--- a/gcc/alias.cc
+++ b/gcc/alias.cc
@@ -3369,6 +3369,10 @@ memory_modified_in_insn_p (const_rtx mem, const_rtx insn)
void
init_alias_analysis (void)
{
+ const bool frame_pointer_eliminated
+ = reload_completed
+ && !frame_pointer_needed
+ && targetm.can_eliminate (FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM);
unsigned int maxreg = max_reg_num ();
int changed, pass;
int i;
@@ -3446,12 +3450,8 @@ init_alias_analysis (void)
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (static_reg_base_value[i]
/* Don't treat the hard frame pointer as special if we
- eliminated the frame pointer to the stack pointer instead. */
- && !(i == HARD_FRAME_POINTER_REGNUM
- && reload_completed
- && !frame_pointer_needed
- && targetm.can_eliminate (FRAME_POINTER_REGNUM,
- STACK_POINTER_REGNUM)))
+ eliminated the frame pointer to the stack pointer. */
+ && !(i == HARD_FRAME_POINTER_REGNUM && frame_pointer_eliminated))
{
new_reg_base_value[i] = static_reg_base_value[i];
bitmap_set_bit (reg_seen, i);
@@ -3467,10 +3467,15 @@ init_alias_analysis (void)
{
rtx note, set;
+ /* Treat the hard frame pointer as special unless we
+ eliminated the frame pointer to the stack pointer. */
+ if (!frame_pointer_eliminated
+ && modified_in_p (hard_frame_pointer_rtx, insn))
+ continue;
+
/* If this insn has a noalias note, process it, Otherwise,
scan for sets. A simple set will have no side effects
which could change the base value of any other register. */
-
if (GET_CODE (PATTERN (insn)) == SET
&& REG_NOTES (insn) != 0
&& find_reg_note (insn, REG_NOALIAS, NULL_RTX))
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] Restore RTL alias analysis for hard frame pointer
2022-10-28 9:10 [PATCH] Restore RTL alias analysis for hard frame pointer Eric Botcazou
@ 2022-10-28 12:27 ` Richard Biener
2022-10-28 12:27 ` Richard Biener
0 siblings, 1 reply; 7+ messages in thread
From: Richard Biener @ 2022-10-28 12:27 UTC (permalink / raw)
To: Eric Botcazou; +Cc: gcc-patches
On Fri, Oct 28, 2022 at 11:11 AM Eric Botcazou via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hi,
>
> the following change:
>
> 2021-07-28 Bin Cheng <bin.cheng@linux.alibaba.com>
>
> * alias.c (init_alias_analysis): Don't skip prologue/epilogue.
>
> broke the alias analysis for the hard frame pointer (when it is used as a
> frame pointer, i.e. when the frame pointer is not eliminated) described in the
> large comment at the top of the file, because static_reg_base_value is set for
> it and, consequently, new_reg_base_value too. So when the instruction saving
> the stack pointer into the hard frame pointer in the prologue is processed, it
> is viewed as a second set of the hard frame pointer and to a different value
> by record_set, which then resets new_reg_base_value to 0 and the game is over.
>
> This e.g. hampers the performance of the var-tracking RTL pass for parameters
> passed on the stack like on x86, leading to regressions when debugging, but
> code generation is very likely affected too.
>
> Bootstrapped/regtested on x86-64/Linux, OK for mainline and 12 branch?
OK for trunk and 12 after a while of burn-in.
Thanks,
Richard.
>
> 2022-10-28 Eric Botcazou <ebotcazou@adacore.com>
>
> * alias.cc (init_alias_analysis): Do not record sets to the hard
> frame pointer if the frame pointer has not been eliminated.
>
> --
> Eric Botcazou
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] Restore RTL alias analysis for hard frame pointer
2022-10-28 12:27 ` Richard Biener
@ 2022-10-28 12:27 ` Richard Biener
2022-10-29 8:19 ` Eric Botcazou
2022-11-09 9:47 ` Eric Botcazou
0 siblings, 2 replies; 7+ messages in thread
From: Richard Biener @ 2022-10-28 12:27 UTC (permalink / raw)
To: Eric Botcazou; +Cc: gcc-patches
On Fri, Oct 28, 2022 at 2:27 PM Richard Biener
<richard.guenther@gmail.com> wrote:
>
> On Fri, Oct 28, 2022 at 11:11 AM Eric Botcazou via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > Hi,
> >
> > the following change:
> >
> > 2021-07-28 Bin Cheng <bin.cheng@linux.alibaba.com>
> >
> > * alias.c (init_alias_analysis): Don't skip prologue/epilogue.
> >
> > broke the alias analysis for the hard frame pointer (when it is used as a
> > frame pointer, i.e. when the frame pointer is not eliminated) described in the
> > large comment at the top of the file, because static_reg_base_value is set for
> > it and, consequently, new_reg_base_value too. So when the instruction saving
> > the stack pointer into the hard frame pointer in the prologue is processed, it
> > is viewed as a second set of the hard frame pointer and to a different value
> > by record_set, which then resets new_reg_base_value to 0 and the game is over.
> >
> > This e.g. hampers the performance of the var-tracking RTL pass for parameters
> > passed on the stack like on x86, leading to regressions when debugging, but
> > code generation is very likely affected too.
> >
> > Bootstrapped/regtested on x86-64/Linux, OK for mainline and 12 branch?
>
> OK for trunk and 12 after a while of burn-in.
Oh, do you have a testcase suitable for the testsuite?
> Thanks,
> Richard.
>
> >
> > 2022-10-28 Eric Botcazou <ebotcazou@adacore.com>
> >
> > * alias.cc (init_alias_analysis): Do not record sets to the hard
> > frame pointer if the frame pointer has not been eliminated.
> >
> > --
> > Eric Botcazou
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] Restore RTL alias analysis for hard frame pointer
2022-10-28 12:27 ` Richard Biener
@ 2022-10-29 8:19 ` Eric Botcazou
2022-10-29 11:03 ` Richard Biener
2022-11-09 9:47 ` Eric Botcazou
1 sibling, 1 reply; 7+ messages in thread
From: Eric Botcazou @ 2022-10-29 8:19 UTC (permalink / raw)
To: Richard Biener; +Cc: gcc-patches
> OK for trunk and 12 after a while of burn-in.
Thanks!
> Oh, do you have a testcase suitable for the testsuite?
I only have an Ada testcase for GDB, let me try to find something more usable.
--
Eric Botcazou
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] Restore RTL alias analysis for hard frame pointer
2022-10-29 8:19 ` Eric Botcazou
@ 2022-10-29 11:03 ` Richard Biener
0 siblings, 0 replies; 7+ messages in thread
From: Richard Biener @ 2022-10-29 11:03 UTC (permalink / raw)
To: Eric Botcazou; +Cc: gcc-patches
> Am 29.10.2022 um 10:19 schrieb Eric Botcazou <botcazou@adacore.com>:
>
>
>>
>> OK for trunk and 12 after a while of burn-in.
>
> Thanks!
>
>> Oh, do you have a testcase suitable for the testsuite?
>
> I only have an Ada testcase for GDB, let me try to find something more usable.
Not too bad if it works to scan-assembler for the DWARF?
> --
> Eric Botcazou
>
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] Restore RTL alias analysis for hard frame pointer
2022-10-28 12:27 ` Richard Biener
2022-10-29 8:19 ` Eric Botcazou
@ 2022-11-09 9:47 ` Eric Botcazou
2022-11-09 10:44 ` Richard Biener
1 sibling, 1 reply; 7+ messages in thread
From: Eric Botcazou @ 2022-11-09 9:47 UTC (permalink / raw)
To: Richard Biener; +Cc: gcc-patches
[-- Attachment #1: Type: text/plain, Size: 3888 bytes --]
> Oh, do you have a testcase suitable for the testsuite?
C guality testcase attached, it fails on x86/Linux with -m32 on the gcc-12
branch (which does not have the fix):
FAIL: gcc.dg/guality/param-6.c -O1 -DPREVENT_OPTIMIZATION line 15 i == 5
FAIL: gcc.dg/guality/param-6.c -O2 -DPREVENT_OPTIMIZATION line 15 i == 5
FAIL: gcc.dg/guality/param-6.c -O3 -g -DPREVENT_OPTIMIZATION line 15 i ==
5
FAIL: gcc.dg/guality/param-6.c -Os -DPREVENT_OPTIMIZATION line 15 i == 5
FAIL: gcc.dg/guality/param-6.c -O2 -flto -fno-use-linker-plugin -flto-
partition=none -DPREVENT_OPTIMIZATION line 15 i == 5
FAIL: gcc.dg/guality/param-6.c -O2 -flto -fuse-linker-plugin -fno-fat-lto-
objects -DPREVENT_OPTIMIZATION line 15 i == 5
but passes on the mainline (which has the fix) and on the gcc-11 branch (which
does not have the issue). The fix also eliminates other regressions:
-FAIL: gcc.dg/guality/drap.c -Os -DPREVENT_OPTIMIZATION line 21 a == 5
-FAIL: gcc.dg/guality/drap.c -Os -DPREVENT_OPTIMIZATION line 22 b == 6
-FAIL: gcc.dg/guality/pr43051-1.c -Os -DPREVENT_OPTIMIZATION line 35 v ==
1
-FAIL: gcc.dg/guality/pr43051-1.c -Os -DPREVENT_OPTIMIZATION line 36 e ==
&a[1]
-FAIL: gcc.dg/guality/pr43051-1.c -Os -DPREVENT_OPTIMIZATION line 40 v ==
1
-FAIL: gcc.dg/guality/pr43051-1.c -Os -DPREVENT_OPTIMIZATION line 41 e ==
&a[1]
-FAIL: gcc.dg/guality/pr43177.c -Os -DPREVENT_OPTIMIZATION line 15 x == 7
-FAIL: gcc.dg/guality/pr54519-3.c -Os -DPREVENT_OPTIMIZATION line 20 y ==
25
-FAIL: gcc.dg/guality/pr54519-3.c -Os -DPREVENT_OPTIMIZATION line 20 z ==
6
-FAIL: gcc.dg/guality/pr54519-3.c -Os -DPREVENT_OPTIMIZATION line 23 y ==
117
-FAIL: gcc.dg/guality/pr54519-3.c -Os -DPREVENT_OPTIMIZATION line 23 z ==
8
-FAIL: gcc.dg/guality/pr54519-4.c -Os -DPREVENT_OPTIMIZATION line 17 y ==
25
-FAIL: gcc.dg/guality/pr54796.c -O1 -DPREVENT_OPTIMIZATION line 17 a == 5
-FAIL: gcc.dg/guality/pr54796.c -O1 -DPREVENT_OPTIMIZATION line 17 b == 6
-FAIL: gcc.dg/guality/pr54796.c -O1 -DPREVENT_OPTIMIZATION line 17 c == 5
-FAIL: gcc.dg/guality/pr54796.c -O2 -DPREVENT_OPTIMIZATION line 17 a == 5
-FAIL: gcc.dg/guality/pr54796.c -O2 -DPREVENT_OPTIMIZATION line 17 b == 6
-FAIL: gcc.dg/guality/pr54796.c -O2 -DPREVENT_OPTIMIZATION line 17 c == 5
-FAIL: gcc.dg/guality/pr54796.c -O3 -g -DPREVENT_OPTIMIZATION line 17 a ==
5
-FAIL: gcc.dg/guality/pr54796.c -O3 -g -DPREVENT_OPTIMIZATION line 17 b ==
6
-FAIL: gcc.dg/guality/pr54796.c -O3 -g -DPREVENT_OPTIMIZATION line 17 c ==
5
-FAIL: gcc.dg/guality/pr54796.c -Os -DPREVENT_OPTIMIZATION line 17 a == 5
-FAIL: gcc.dg/guality/pr54796.c -Os -DPREVENT_OPTIMIZATION line 17 b == 6
-FAIL: gcc.dg/guality/pr54796.c -Os -DPREVENT_OPTIMIZATION line 17 c == 5
-FAIL: gcc.dg/guality/pr54796.c -O2 -flto -fno-use-linker-plugin -flto-
partition=none -DPREVENT_OPTIMIZATION line 17 a == 5
-FAIL: gcc.dg/guality/pr54796.c -O2 -flto -fno-use-linker-plugin -flto-
partition=none -DPREVENT_OPTIMIZATION line 17 b == 6
-FAIL: gcc.dg/guality/pr54796.c -O2 -flto -fno-use-linker-plugin -flto-
partition=none -DPREVENT_OPTIMIZATION line 17 c == 5
-FAIL: gcc.dg/guality/sra-1.c -Os -DPREVENT_OPTIMIZATION line 43 a.j == 14
-FAIL: gcc.dg/guality/vla-1.c -O1 -DPREVENT_OPTIMIZATION line 24 i == 5
-FAIL: gcc.dg/guality/vla-1.c -O2 -DPREVENT_OPTIMIZATION line 24 i == 5
-FAIL: gcc.dg/guality/vla-1.c -O3 -g -DPREVENT_OPTIMIZATION line 24 i == 5
-FAIL: gcc.dg/guality/vla-1.c -Os -DPREVENT_OPTIMIZATION line 24 i == 5
-FAIL: gcc.dg/guality/vla-1.c -O2 -flto -fno-use-linker-plugin -flto-
partition=none -DPREVENT_OPTIMIZATION line 24 i == 5
present on the gcc-12 branch wrt the gcc-11 branch (apparently nobody really
cares about the guality testsuite on x86/Linux).
* gcc.dg/guality/param-6.c: New test.
--
Eric Botcazou
[-- Attachment #2: param-6.c --]
[-- Type: text/x-csrc, Size: 334 bytes --]
/* { dg-do run { target i?86-*-* x86_64-*-* } } */
/* { dg-options "-g" } */
void __attribute__((noipa)) bar (void *p)
{}
void __attribute__((noipa)) foo (int i)
{
void *p = __builtin_alloca (i);
asm volatile ("" : : : "ebx");
bar (p); /* { dg-final { gdb-test . "i" "5" } } */
}
int main (void)
{
foo (5);
return 0;
}
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] Restore RTL alias analysis for hard frame pointer
2022-11-09 9:47 ` Eric Botcazou
@ 2022-11-09 10:44 ` Richard Biener
0 siblings, 0 replies; 7+ messages in thread
From: Richard Biener @ 2022-11-09 10:44 UTC (permalink / raw)
To: Eric Botcazou; +Cc: gcc-patches
> Am 09.11.2022 um 10:49 schrieb Eric Botcazou <botcazou@adacore.com>:
>
>
>>
>> Oh, do you have a testcase suitable for the testsuite?
>
> C guality testcase attached, it fails on x86/Linux with -m32 on the gcc-12
> branch (which does not have the fix):
>
> FAIL: gcc.dg/guality/param-6.c -O1 -DPREVENT_OPTIMIZATION line 15 i == 5
> FAIL: gcc.dg/guality/param-6.c -O2 -DPREVENT_OPTIMIZATION line 15 i == 5
> FAIL: gcc.dg/guality/param-6.c -O3 -g -DPREVENT_OPTIMIZATION line 15 i ==
> 5
> FAIL: gcc.dg/guality/param-6.c -Os -DPREVENT_OPTIMIZATION line 15 i == 5
> FAIL: gcc.dg/guality/param-6.c -O2 -flto -fno-use-linker-plugin -flto-
> partition=none -DPREVENT_OPTIMIZATION line 15 i == 5
> FAIL: gcc.dg/guality/param-6.c -O2 -flto -fuse-linker-plugin -fno-fat-lto-
> objects -DPREVENT_OPTIMIZATION line 15 i == 5
>
> but passes on the mainline (which has the fix) and on the gcc-11 branch (which
> does not have the issue). The fix also eliminates other regressions:
>
> -FAIL: gcc.dg/guality/drap.c -Os -DPREVENT_OPTIMIZATION line 21 a == 5
> -FAIL: gcc.dg/guality/drap.c -Os -DPREVENT_OPTIMIZATION line 22 b == 6
> -FAIL: gcc.dg/guality/pr43051-1.c -Os -DPREVENT_OPTIMIZATION line 35 v ==
> 1
> -FAIL: gcc.dg/guality/pr43051-1.c -Os -DPREVENT_OPTIMIZATION line 36 e ==
> &a[1]
> -FAIL: gcc.dg/guality/pr43051-1.c -Os -DPREVENT_OPTIMIZATION line 40 v ==
> 1
> -FAIL: gcc.dg/guality/pr43051-1.c -Os -DPREVENT_OPTIMIZATION line 41 e ==
> &a[1]
> -FAIL: gcc.dg/guality/pr43177.c -Os -DPREVENT_OPTIMIZATION line 15 x == 7
> -FAIL: gcc.dg/guality/pr54519-3.c -Os -DPREVENT_OPTIMIZATION line 20 y ==
> 25
> -FAIL: gcc.dg/guality/pr54519-3.c -Os -DPREVENT_OPTIMIZATION line 20 z ==
> 6
> -FAIL: gcc.dg/guality/pr54519-3.c -Os -DPREVENT_OPTIMIZATION line 23 y ==
> 117
> -FAIL: gcc.dg/guality/pr54519-3.c -Os -DPREVENT_OPTIMIZATION line 23 z ==
> 8
> -FAIL: gcc.dg/guality/pr54519-4.c -Os -DPREVENT_OPTIMIZATION line 17 y ==
> 25
> -FAIL: gcc.dg/guality/pr54796.c -O1 -DPREVENT_OPTIMIZATION line 17 a == 5
> -FAIL: gcc.dg/guality/pr54796.c -O1 -DPREVENT_OPTIMIZATION line 17 b == 6
> -FAIL: gcc.dg/guality/pr54796.c -O1 -DPREVENT_OPTIMIZATION line 17 c == 5
> -FAIL: gcc.dg/guality/pr54796.c -O2 -DPREVENT_OPTIMIZATION line 17 a == 5
> -FAIL: gcc.dg/guality/pr54796.c -O2 -DPREVENT_OPTIMIZATION line 17 b == 6
> -FAIL: gcc.dg/guality/pr54796.c -O2 -DPREVENT_OPTIMIZATION line 17 c == 5
> -FAIL: gcc.dg/guality/pr54796.c -O3 -g -DPREVENT_OPTIMIZATION line 17 a ==
> 5
> -FAIL: gcc.dg/guality/pr54796.c -O3 -g -DPREVENT_OPTIMIZATION line 17 b ==
> 6
> -FAIL: gcc.dg/guality/pr54796.c -O3 -g -DPREVENT_OPTIMIZATION line 17 c ==
> 5
> -FAIL: gcc.dg/guality/pr54796.c -Os -DPREVENT_OPTIMIZATION line 17 a == 5
> -FAIL: gcc.dg/guality/pr54796.c -Os -DPREVENT_OPTIMIZATION line 17 b == 6
> -FAIL: gcc.dg/guality/pr54796.c -Os -DPREVENT_OPTIMIZATION line 17 c == 5
> -FAIL: gcc.dg/guality/pr54796.c -O2 -flto -fno-use-linker-plugin -flto-
> partition=none -DPREVENT_OPTIMIZATION line 17 a == 5
> -FAIL: gcc.dg/guality/pr54796.c -O2 -flto -fno-use-linker-plugin -flto-
> partition=none -DPREVENT_OPTIMIZATION line 17 b == 6
> -FAIL: gcc.dg/guality/pr54796.c -O2 -flto -fno-use-linker-plugin -flto-
> partition=none -DPREVENT_OPTIMIZATION line 17 c == 5
> -FAIL: gcc.dg/guality/sra-1.c -Os -DPREVENT_OPTIMIZATION line 43 a.j == 14
> -FAIL: gcc.dg/guality/vla-1.c -O1 -DPREVENT_OPTIMIZATION line 24 i == 5
> -FAIL: gcc.dg/guality/vla-1.c -O2 -DPREVENT_OPTIMIZATION line 24 i == 5
> -FAIL: gcc.dg/guality/vla-1.c -O3 -g -DPREVENT_OPTIMIZATION line 24 i == 5
> -FAIL: gcc.dg/guality/vla-1.c -Os -DPREVENT_OPTIMIZATION line 24 i == 5
> -FAIL: gcc.dg/guality/vla-1.c -O2 -flto -fno-use-linker-plugin -flto-
> partition=none -DPREVENT_OPTIMIZATION line 24 i == 5
>
> present on the gcc-12 branch wrt the gcc-11 branch (apparently nobody really
> cares about the guality testsuite on x86/Linux).
Thanks a lot, OK.
Richard
>
>
> * gcc.dg/guality/param-6.c: New test.
>
> --
> Eric Botcazou
> <param-6.c>
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-11-09 10:44 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-10-28 9:10 [PATCH] Restore RTL alias analysis for hard frame pointer Eric Botcazou
2022-10-28 12:27 ` Richard Biener
2022-10-28 12:27 ` Richard Biener
2022-10-29 8:19 ` Eric Botcazou
2022-10-29 11:03 ` Richard Biener
2022-11-09 9:47 ` Eric Botcazou
2022-11-09 10:44 ` Richard Biener
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