* [PATCH] x86: Save callee-saved registers in noreturn functions for -O0/-Og
@ 2024-01-27 13:52 H.J. Lu
2024-01-27 14:09 ` Jakub Jelinek
0 siblings, 1 reply; 5+ messages in thread
From: H.J. Lu @ 2024-01-27 13:52 UTC (permalink / raw)
To: gcc-patches
Save callee-saved registers in noreturn functions for -O0/-Og so that
debugger can restore callee-saved registers in caller's frame.
gcc/
PR target/38534
* config/i386/i386-options.cc (ix86_set_func_type): Save
callee-saved registers in noreturn functions for -O0/-Og.
gcc/testsuite/
PR target/38534
* gcc.target/i386/pr38534-5.c: New file.
* gcc.target/i386/pr38534-6.c: Likewise.
---
gcc/config/i386/i386-options.cc | 7 ++++--
gcc/testsuite/gcc.target/i386/pr38534-5.c | 26 +++++++++++++++++++++++
gcc/testsuite/gcc.target/i386/pr38534-6.c | 26 +++++++++++++++++++++++
3 files changed, 57 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/pr38534-5.c
create mode 100644 gcc/testsuite/gcc.target/i386/pr38534-6.c
diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc
index 473f5359fc9..5ff5560df7a 100644
--- a/gcc/config/i386/i386-options.cc
+++ b/gcc/config/i386/i386-options.cc
@@ -3381,7 +3381,8 @@ static void
ix86_set_func_type (tree fndecl)
{
/* No need to save and restore callee-saved registers for a noreturn
- function with nothrow or compiled with -fno-exceptions.
+ function with nothrow or compiled with -fno-exceptions unless when
+ compiling with -O0 or -Og.
NB: Don't use TREE_THIS_VOLATILE to check if this is a noreturn
function. The local-pure-const pass turns an interrupt function
@@ -3391,7 +3392,9 @@ ix86_set_func_type (tree fndecl)
function is marked as noreturn in the IR output, which leads the
incompatible attribute error in LTO1. */
bool has_no_callee_saved_registers
- = (((TREE_NOTHROW (fndecl) || !flag_exceptions)
+ = ((optimize
+ && !optimize_debug
+ && (TREE_NOTHROW (fndecl) || !flag_exceptions)
&& lookup_attribute ("noreturn", DECL_ATTRIBUTES (fndecl)))
|| lookup_attribute ("no_callee_saved_registers",
TYPE_ATTRIBUTES (TREE_TYPE (fndecl))));
diff --git a/gcc/testsuite/gcc.target/i386/pr38534-5.c b/gcc/testsuite/gcc.target/i386/pr38534-5.c
new file mode 100644
index 00000000000..91c0c0f8c59
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr38534-5.c
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-O0 -mtune-ctrl=^prologue_using_move,^epilogue_using_move" } */
+
+#define ARRAY_SIZE 256
+
+extern int array[ARRAY_SIZE][ARRAY_SIZE][ARRAY_SIZE];
+extern int value (int, int, int)
+#ifndef __x86_64__
+__attribute__ ((regparm(3)))
+#endif
+;
+
+void
+__attribute__((noreturn))
+no_return_to_caller (void)
+{
+ unsigned i, j, k;
+ for (i = ARRAY_SIZE; i > 0; --i)
+ for (j = ARRAY_SIZE; j > 0; --j)
+ for (k = ARRAY_SIZE; k > 0; --k)
+ array[i - 1][j - 1][k - 1] = value (i, j, k);
+ while (1);
+}
+
+/* { dg-final { scan-assembler "push" } } */
+/* { dg-final { scan-assembler-not "pop" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr38534-6.c b/gcc/testsuite/gcc.target/i386/pr38534-6.c
new file mode 100644
index 00000000000..756e1ec81f5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr38534-6.c
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-Og -mtune-ctrl=^prologue_using_move,^epilogue_using_move" } */
+
+#define ARRAY_SIZE 256
+
+extern int array[ARRAY_SIZE][ARRAY_SIZE][ARRAY_SIZE];
+extern int value (int, int, int)
+#ifndef __x86_64__
+__attribute__ ((regparm(3)))
+#endif
+;
+
+void
+__attribute__((noreturn))
+no_return_to_caller (void)
+{
+ unsigned i, j, k;
+ for (i = ARRAY_SIZE; i > 0; --i)
+ for (j = ARRAY_SIZE; j > 0; --j)
+ for (k = ARRAY_SIZE; k > 0; --k)
+ array[i - 1][j - 1][k - 1] = value (i, j, k);
+ while (1);
+}
+
+/* { dg-final { scan-assembler "push" } } */
+/* { dg-final { scan-assembler-not "pop" } } */
--
2.43.0
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] x86: Save callee-saved registers in noreturn functions for -O0/-Og
2024-01-27 13:52 [PATCH] x86: Save callee-saved registers in noreturn functions for -O0/-Og H.J. Lu
@ 2024-01-27 14:09 ` Jakub Jelinek
2024-01-27 15:00 ` H.J. Lu
0 siblings, 1 reply; 5+ messages in thread
From: Jakub Jelinek @ 2024-01-27 14:09 UTC (permalink / raw)
To: H.J. Lu; +Cc: gcc-patches
On Sat, Jan 27, 2024 at 05:52:34AM -0800, H.J. Lu wrote:
> @@ -3391,7 +3392,9 @@ ix86_set_func_type (tree fndecl)
> function is marked as noreturn in the IR output, which leads the
> incompatible attribute error in LTO1. */
> bool has_no_callee_saved_registers
> - = (((TREE_NOTHROW (fndecl) || !flag_exceptions)
> + = ((optimize
> + && !optimize_debug
Shouldn't that be opt_for_fn (fndecl, optimize) and ditto for
optimize_debug?
I mean, aren't the options not restored yet when this function is called
(i.e. remain in whatever state they were in the previous function or
global state)?
Also, shouldn't the lookup_attribute ("noreturn" check be the first one?
I mean, noreturn functions are quite rare and so checking all the other
conditions upon each set_cfun could waste too much compile time.
Also, why check "noreturn" attribute rather than
TREE_THIS_VOLATILE (fndecl)?
Jakub
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] x86: Save callee-saved registers in noreturn functions for -O0/-Og
2024-01-27 14:09 ` Jakub Jelinek
@ 2024-01-27 15:00 ` H.J. Lu
2024-01-29 10:11 ` Jakub Jelinek
0 siblings, 1 reply; 5+ messages in thread
From: H.J. Lu @ 2024-01-27 15:00 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: gcc-patches
On Sat, Jan 27, 2024 at 6:09 AM Jakub Jelinek <jakub@redhat.com> wrote:
>
> On Sat, Jan 27, 2024 at 05:52:34AM -0800, H.J. Lu wrote:
> > @@ -3391,7 +3392,9 @@ ix86_set_func_type (tree fndecl)
> > function is marked as noreturn in the IR output, which leads the
> > incompatible attribute error in LTO1. */
> > bool has_no_callee_saved_registers
> > - = (((TREE_NOTHROW (fndecl) || !flag_exceptions)
> > + = ((optimize
> > + && !optimize_debug
>
> Shouldn't that be opt_for_fn (fndecl, optimize) and ditto for
> optimize_debug?
> I mean, aren't the options not restored yet when this function is called
> (i.e. remain in whatever state they were in the previous function or
> global state)?
store_parm_decls is called when parsing a function. store_parm_decls
calls allocate_struct_function which calls
invoke_set_current_function_hook (fndecl);
which has
/* Change optimization options if needed. */
if (optimization_current_node != opts)
{
optimization_current_node = opts;
cl_optimization_restore (&global_options, &global_options_set,
TREE_OPTIMIZATION (opts));
}
targetm.set_current_function (fndecl);
which calls ix86_set_current_function after global_options
has been updated. ix86_set_func_type is called from
ix86_set_current_function.
I don't see an issue with optimize and optimize_debug here.
> Also, shouldn't the lookup_attribute ("noreturn" check be the first one?
> I mean, noreturn functions are quite rare and so checking all the other
I will fix it and updated one testcase with
__attribute__((noreturn, optimize("-Og")))
> conditions upon each set_cfun could waste too much compile time.
>
> Also, why check "noreturn" attribute rather than
> TREE_THIS_VOLATILE (fndecl)?
>
The comments above this code has
NB: Don't use TREE_THIS_VOLATILE to check if this is a noreturn
function. The local-pure-const pass turns an interrupt function
into a noreturn function by setting TREE_THIS_VOLATILE. Normally
the local-pure-const pass is run after ix86_set_func_type is called.
When the local-pure-const pass is enabled for LTO, the interrupt
function is marked as noreturn in the IR output, which leads the
incompatible attribute error in LTO1.
Thanks.
--
H.J.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] x86: Save callee-saved registers in noreturn functions for -O0/-Og
2024-01-27 15:00 ` H.J. Lu
@ 2024-01-29 10:11 ` Jakub Jelinek
2024-01-29 13:27 ` H.J. Lu
0 siblings, 1 reply; 5+ messages in thread
From: Jakub Jelinek @ 2024-01-29 10:11 UTC (permalink / raw)
To: H.J. Lu; +Cc: gcc-patches
On Sat, Jan 27, 2024 at 07:00:03AM -0800, H.J. Lu wrote:
> On Sat, Jan 27, 2024 at 6:09 AM Jakub Jelinek <jakub@redhat.com> wrote:
> >
> > On Sat, Jan 27, 2024 at 05:52:34AM -0800, H.J. Lu wrote:
> > > @@ -3391,7 +3392,9 @@ ix86_set_func_type (tree fndecl)
> > > function is marked as noreturn in the IR output, which leads the
> > > incompatible attribute error in LTO1. */
> > > bool has_no_callee_saved_registers
> > > - = (((TREE_NOTHROW (fndecl) || !flag_exceptions)
> > > + = ((optimize
> > > + && !optimize_debug
> >
> > Shouldn't that be opt_for_fn (fndecl, optimize) and ditto for
> > optimize_debug?
> > I mean, aren't the options not restored yet when this function is called
> > (i.e. remain in whatever state they were in the previous function or
> > global state)?
>
> store_parm_decls is called when parsing a function. store_parm_decls
> calls allocate_struct_function which calls
>
> invoke_set_current_function_hook (fndecl);
>
> which has
>
> /* Change optimization options if needed. */
> if (optimization_current_node != opts)
> {
> optimization_current_node = opts;
> cl_optimization_restore (&global_options, &global_options_set,
> TREE_OPTIMIZATION (opts));
> }
>
> targetm.set_current_function (fndecl);
>
> which calls ix86_set_current_function after global_options
> has been updated. ix86_set_func_type is called from
> ix86_set_current_function.
Sorry, you're right, I just saw option restore later in ix86_set_current_function
and missed that it is target option restore only.
> > Also, why check "noreturn" attribute rather than
> > TREE_THIS_VOLATILE (fndecl)?
> >
>
> The comments above this code has
>
> NB: Don't use TREE_THIS_VOLATILE to check if this is a noreturn
> function. The local-pure-const pass turns an interrupt function
> into a noreturn function by setting TREE_THIS_VOLATILE. Normally
> the local-pure-const pass is run after ix86_set_func_type is called.
> When the local-pure-const pass is enabled for LTO, the interrupt
> function is marked as noreturn in the IR output, which leads the
> incompatible attribute error in LTO1.
So in that case, I think it would be best to test
TREE_THIS_VOLATILE (fndecl)
&& lookup_attribute ("noreturn", DECL_ATTRIBUTES (fndecl))
&& ...
because if it doesn't have noreturn attribute, it will not have
TREE_THIS_VOLATILE set and TREE_THIS_VOLATILE is much cheaper to test than
looking an attribute.
Jakub
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] x86: Save callee-saved registers in noreturn functions for -O0/-Og
2024-01-29 10:11 ` Jakub Jelinek
@ 2024-01-29 13:27 ` H.J. Lu
0 siblings, 0 replies; 5+ messages in thread
From: H.J. Lu @ 2024-01-29 13:27 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: gcc-patches
On Mon, Jan 29, 2024 at 2:11 AM Jakub Jelinek <jakub@redhat.com> wrote:
>
> On Sat, Jan 27, 2024 at 07:00:03AM -0800, H.J. Lu wrote:
> > On Sat, Jan 27, 2024 at 6:09 AM Jakub Jelinek <jakub@redhat.com> wrote:
> > >
> > > On Sat, Jan 27, 2024 at 05:52:34AM -0800, H.J. Lu wrote:
> > > > @@ -3391,7 +3392,9 @@ ix86_set_func_type (tree fndecl)
> > > > function is marked as noreturn in the IR output, which leads the
> > > > incompatible attribute error in LTO1. */
> > > > bool has_no_callee_saved_registers
> > > > - = (((TREE_NOTHROW (fndecl) || !flag_exceptions)
> > > > + = ((optimize
> > > > + && !optimize_debug
> > >
> > > Shouldn't that be opt_for_fn (fndecl, optimize) and ditto for
> > > optimize_debug?
> > > I mean, aren't the options not restored yet when this function is called
> > > (i.e. remain in whatever state they were in the previous function or
> > > global state)?
> >
> > store_parm_decls is called when parsing a function. store_parm_decls
> > calls allocate_struct_function which calls
> >
> > invoke_set_current_function_hook (fndecl);
> >
> > which has
> >
> > /* Change optimization options if needed. */
> > if (optimization_current_node != opts)
> > {
> > optimization_current_node = opts;
> > cl_optimization_restore (&global_options, &global_options_set,
> > TREE_OPTIMIZATION (opts));
> > }
> >
> > targetm.set_current_function (fndecl);
> >
> > which calls ix86_set_current_function after global_options
> > has been updated. ix86_set_func_type is called from
> > ix86_set_current_function.
>
> Sorry, you're right, I just saw option restore later in ix86_set_current_function
> and missed that it is target option restore only.
>
> > > Also, why check "noreturn" attribute rather than
> > > TREE_THIS_VOLATILE (fndecl)?
> > >
> >
> > The comments above this code has
> >
> > NB: Don't use TREE_THIS_VOLATILE to check if this is a noreturn
> > function. The local-pure-const pass turns an interrupt function
> > into a noreturn function by setting TREE_THIS_VOLATILE. Normally
> > the local-pure-const pass is run after ix86_set_func_type is called.
> > When the local-pure-const pass is enabled for LTO, the interrupt
> > function is marked as noreturn in the IR output, which leads the
> > incompatible attribute error in LTO1.
>
> So in that case, I think it would be best to test
> TREE_THIS_VOLATILE (fndecl)
> && lookup_attribute ("noreturn", DECL_ATTRIBUTES (fndecl))
> && ...
> because if it doesn't have noreturn attribute, it will not have
> TREE_THIS_VOLATILE set and TREE_THIS_VOLATILE is much cheaper to test than
> looking an attribute.
>
Fixed in the v3 patch:
https://patchwork.sourceware.org/project/gcc/list/?series=30308
Thanks.
--
H.J.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2024-01-27 13:52 [PATCH] x86: Save callee-saved registers in noreturn functions for -O0/-Og H.J. Lu
2024-01-27 14:09 ` Jakub Jelinek
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