From: Thomas Schwinge <thomas@codesourcery.com>
To: Tom de Vries <tdevries@suse.de>
Cc: <gcc-patches@gcc.gnu.org>
Subject: Re: [committed][nvptx] Use .alias directive for mptx >= 6.3
Date: Fri, 2 Dec 2022 12:24:58 +0100 [thread overview]
Message-ID: <87iliurqt1.fsf@euler.schwinge.homeip.net> (raw)
In-Reply-To: <20220322134144.GA32400@delia.home>
[-- Attachment #1: Type: text/plain, Size: 15507 bytes --]
Hi Tom!
(My following analysis and WIP patch is from a few months ago, but I
thought I'd send it now, in case you've got any comments, and to avoid
potential duplicate work.)
On 2022-03-22T14:41:46+0100, Tom de Vries via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> Starting with ptx isa version 6.3, a ptx directive .alias is available.
> Use this directive to support symbol aliases, as far as possible.
>
> The alias support is off by default. It can be turned on using a switch
> -malias.
>
> Furthermore, for pre-sm_75, it's not effective unless the ptx version is
> bumped to 6.3 or higher using -mptx (given that the default for pre-sm_75 is
> 6.0).
>
> The alias support has the following limitations.
> [...]
> This patch causes a regression:
> ...
> -PASS: gcc.dg/pr60797.c (test for errors, line 4)
> +FAIL: gcc.dg/pr60797.c (test for errors, line 4)
> ...
> The test-case is skipped for effective target alias, and both without and with
> this patch the nvptx target is considered to not support it, so the test-case is
> executed. The test-case expects an error message along the lines of "alias
> definitions not supported in this configuration", but instead we run into:
> ...
> gcc.dg/pr60797.c:4:12: error: foo aliased to undefined symbol
> ...
> This is probably due to the fact that the nvptx backend now defines macros
> ASM_OUTPUT_DEF and ASM_OUTPUT_DEF_FROM_DECLS, so from the point of view of the
> common part of the compiler, aliases are supported.
Testing this with the new '-malias' flag not active (default), I'm seeing
a number of more regressions:
[...]: error: alias definitions not supported in this configuration
[-PASS:-]{+FAIL:+} gcc.dg/pr56727-1.c (test for excess errors)
PASS: gcc.dg/pr84739.c (test for warnings, line 6)
PASS: gcc.dg/pr84739.c (test for warnings, line 21)
[-PASS:-]{+FAIL:+} gcc.dg/pr84739.c (test for excess errors)
[-PASS:-]{+FAIL:+} gcc.dg/ipa/pr81520.c (test for excess errors)
..., and then, in particular, a ton of regressions in GCC/C++ testing
('check-gcc-c++') due to approximately 40000 new
"error: alias definitions not supported in this configuration"
diagnostics. Whoops... (I suppose you've not tested that at all?)
If the new '-malias' flag is not active, we have to maintain (restore)
the previous state of other macros, as I'm demonstrating in the attached
"[WIP] nvptx 'TARGET_USE_LOCAL_THUNK_ALIAS_P', 'TARGET_SUPPORTS_ALIASES'".
This completely addresses in particular the 'check-gcc-c++' regressions,
and does not cause any changes if the new '-malias' flag in fact is
active (as when testing with '-mptx=6.3 -malias', for example).
However, this further regresses the 'gcc.dg/pr56727-1.c' and
'gcc.dg/ipa/pr81520.c' test cases mentioned above:
during IPA pass: whole-program
[...]: internal compiler error: in function_and_variable_visibility, at ipa-visibility.cc:647
{+FAIL: gcc.dg/pr56727-1.c (internal compiler error: in function_and_variable_visibility, at ipa-visibility.cc:647)+}
FAIL: gcc.dg/pr56727-1.c (test for excess errors)
{+FAIL: gcc.dg/ipa/pr81520.c (internal compiler error: in function_and_variable_visibility, at ipa-visibility.cc:647)+}
FAIL: gcc.dg/ipa/pr81520.c (test for excess errors)
Such ICEs we're not yet currently seeing elsewhere; this remains to be
analyzed -- after all, these test cases PASSed originally.
And, obviously, the patch needs some "copy editing".
Grüße
Thomas
> [nvptx] Use .alias directive for mptx >= 6.3
>
> gcc/ChangeLog:
>
> 2022-03-18 Tom de Vries <tdevries@suse.de>
>
> PR target/104957
> * config/nvptx/nvptx-protos.h (nvptx_asm_output_def_from_decls): Declare.
> * config/nvptx/nvptx.cc (write_fn_proto_1): Don't add function marker
> for alias.
> (SET_ASM_OP, NVPTX_ASM_OUTPUT_DEF): New macro def.
> (nvptx_asm_output_def_from_decls): New function.
> * config/nvptx/nvptx.h (ASM_OUTPUT_DEF): New macro def, define to
> gcc_unreachable ().
> (ASM_OUTPUT_DEF_FROM_DECLS): New macro def, define to
> nvptx_asm_output_def_from_decls.
> * config/nvptx/nvptx.opt (malias): New opt.
>
> gcc/testsuite/ChangeLog:
>
> 2022-03-18 Tom de Vries <tdevries@suse.de>
>
> PR target/104957
> * gcc.target/nvptx/alias-1.c: New test.
> * gcc.target/nvptx/alias-2.c: New test.
> * gcc.target/nvptx/alias-3.c: New test.
> * gcc.target/nvptx/alias-4.c: New test.
> * gcc.target/nvptx/nvptx.exp
> (check_effective_target_runtime_ptx_isa_version_6_3): New proc.
>
> ---
> gcc/config/nvptx/nvptx-protos.h | 1 +
> gcc/config/nvptx/nvptx.cc | 74 +++++++++++++++++++++++++++++++-
> gcc/config/nvptx/nvptx.h | 17 ++++++++
> gcc/config/nvptx/nvptx.opt | 3 ++
> gcc/testsuite/gcc.target/nvptx/alias-1.c | 27 ++++++++++++
> gcc/testsuite/gcc.target/nvptx/alias-2.c | 13 ++++++
> gcc/testsuite/gcc.target/nvptx/alias-3.c | 29 +++++++++++++
> gcc/testsuite/gcc.target/nvptx/alias-4.c | 12 ++++++
> gcc/testsuite/gcc.target/nvptx/nvptx.exp | 7 +++
> 9 files changed, 182 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/config/nvptx/nvptx-protos.h b/gcc/config/nvptx/nvptx-protos.h
> index 0bf9af406a2..ca0a87ee4bd 100644
> --- a/gcc/config/nvptx/nvptx-protos.h
> +++ b/gcc/config/nvptx/nvptx-protos.h
> @@ -43,6 +43,7 @@ extern void nvptx_output_ascii (FILE *, const char *, unsigned HOST_WIDE_INT);
> extern void nvptx_cpu_cpp_builtins (void);
> extern void nvptx_register_pragmas (void);
> extern unsigned int nvptx_data_alignment (const_tree, unsigned int);
> +extern void nvptx_asm_output_def_from_decls (FILE *, tree, tree);
>
> #ifdef RTX_CODE
> extern void nvptx_expand_oacc_fork (unsigned);
> diff --git a/gcc/config/nvptx/nvptx.cc b/gcc/config/nvptx/nvptx.cc
> index f83f98c3ab5..b2f7b4af392 100644
> --- a/gcc/config/nvptx/nvptx.cc
> +++ b/gcc/config/nvptx/nvptx.cc
> @@ -77,6 +77,7 @@
> #include "opts.h"
> #include "tree-pretty-print.h"
> #include "rtl-iter.h"
> +#include "cgraph.h"
>
> /* This file should be included last. */
> #include "target-def.h"
> @@ -968,7 +969,8 @@ static void
> write_fn_proto_1 (std::stringstream &s, bool is_defn,
> const char *name, const_tree decl)
> {
> - write_fn_marker (s, is_defn, TREE_PUBLIC (decl), name);
> + if (lookup_attribute ("alias", DECL_ATTRIBUTES (decl)) == NULL)
> + write_fn_marker (s, is_defn, TREE_PUBLIC (decl), name);
>
> /* PTX declaration. */
> if (DECL_EXTERNAL (decl))
> @@ -7393,6 +7395,76 @@ nvptx_mem_local_p (rtx mem)
> return false;
> }
>
> +/* Define locally, for use in NVPTX_ASM_OUTPUT_DEF. */
> +#define SET_ASM_OP ".alias "
> +
> +/* Define locally, for use in nvptx_asm_output_def_from_decls. Add NVPTX_
> + prefix to avoid clash with ASM_OUTPUT_DEF from nvptx.h.
> + Copy of ASM_OUTPUT_DEF from defaults.h, with added terminating
> + semicolon. */
> +#define NVPTX_ASM_OUTPUT_DEF(FILE,LABEL1,LABEL2) \
> + do \
> + { \
> + fprintf ((FILE), "%s", SET_ASM_OP); \
> + assemble_name (FILE, LABEL1); \
> + fprintf (FILE, ","); \
> + assemble_name (FILE, LABEL2); \
> + fprintf (FILE, ";\n"); \
> + } \
> + while (0)
> +
> +void
> +nvptx_asm_output_def_from_decls (FILE *stream, tree name, tree value)
> +{
> + if (nvptx_alias == 0 || !TARGET_PTX_6_3)
> + {
> + /* Copied from assemble_alias. */
> + error_at (DECL_SOURCE_LOCATION (name),
> + "alias definitions not supported in this configuration");
> + TREE_ASM_WRITTEN (name) = 1;
> + return;
> + }
> +
> + if (lookup_attribute ("weak", DECL_ATTRIBUTES (name)))
> + {
> + /* Prevent execution FAILs for gcc.dg/globalalias.c and
> + gcc.dg/pr77587.c. */
> + error_at (DECL_SOURCE_LOCATION (name),
> + "weak alias definitions not supported in this configuration");
> + TREE_ASM_WRITTEN (name) = 1;
> + return;
> + }
> +
> + /* Ptx also doesn't support value having weak linkage, but we can't detect
> + that here, so we'll end up with:
> + "error: Function test with .weak scope cannot be aliased".
> + See gcc.dg/localalias.c. */
> +
> + if (TREE_CODE (name) != FUNCTION_DECL)
> + {
> + error_at (DECL_SOURCE_LOCATION (name),
> + "non-function alias definitions not supported"
> + " in this configuration");
> + TREE_ASM_WRITTEN (name) = 1;
> + return;
> + }
> +
> + if (!cgraph_node::get (name)->referred_to_p ())
> + /* Prevent "Internal error: reference to deleted section". */
> + return;
> +
> + std::stringstream s;
> + write_fn_proto (s, false, get_fnname_from_decl (name), name);
> + fputs (s.str ().c_str (), stream);
> +
> + tree id = DECL_ASSEMBLER_NAME (name);
> + NVPTX_ASM_OUTPUT_DEF (stream, IDENTIFIER_POINTER (id),
> + IDENTIFIER_POINTER (value));
> +}
> +
> +#undef NVPTX_ASM_OUTPUT_DEF
> +#undef SET_ASM_OP
> +
> #undef TARGET_OPTION_OVERRIDE
> #define TARGET_OPTION_OVERRIDE nvptx_option_override
>
> diff --git a/gcc/config/nvptx/nvptx.h b/gcc/config/nvptx/nvptx.h
> index b55ade65cc5..75ac7a666b1 100644
> --- a/gcc/config/nvptx/nvptx.h
> +++ b/gcc/config/nvptx/nvptx.h
> @@ -315,6 +315,23 @@ struct GTY(()) machine_function
> ((VALUE) = GET_MODE_BITSIZE ((MODE)), 2)
>
> #define SUPPORTS_WEAK 1
> +
> +/* The documentation states that ASM_OUTPUT_DEF_FROM_DECLS is used in
> + preference to ASM_OUTPUT_DEF if the tree nodes are available. However, we
> + need the tree nodes to emit the prototype, so at this point it's not clear
> + how we can support ASM_OUTPUT_DEF. Still, we need to define it, or
> + ASM_OUTPUT_DEF_FROM_DECLS is ignored. For now, assert, and once we run
> + into it possibly improve by somehow emitting the prototype elsewhere, or
> + emitting a reasonable error message. */
> +#define ASM_OUTPUT_DEF(FILE,LABEL1,LABEL2) \
> + do \
> + { \
> + gcc_unreachable (); \
> + } \
> + while (0)
> +#define ASM_OUTPUT_DEF_FROM_DECLS(STREAM, NAME, VALUE) \
> + nvptx_asm_output_def_from_decls (STREAM, NAME, VALUE)
> +
> #define NO_DOT_IN_LABEL
> #define ASM_COMMENT_START "//"
>
> diff --git a/gcc/config/nvptx/nvptx.opt b/gcc/config/nvptx/nvptx.opt
> index fea99c5d406..980428b58cc 100644
> --- a/gcc/config/nvptx/nvptx.opt
> +++ b/gcc/config/nvptx/nvptx.opt
> @@ -85,3 +85,6 @@ Initialize ptx registers.
>
> mptx-comment
> Target Var(nvptx_comment) Init(1) Undocumented
> +
> +malias
> +Target Var(nvptx_alias) Init(0) Undocumented
> diff --git a/gcc/testsuite/gcc.target/nvptx/alias-1.c b/gcc/testsuite/gcc.target/nvptx/alias-1.c
> new file mode 100644
> index 00000000000..f68716e77dd
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/nvptx/alias-1.c
> @@ -0,0 +1,27 @@
> +/* { dg-do link } */
> +/* { dg-do run { target runtime_ptx_isa_version_6_3 } } */
> +/* { dg-options "-save-temps -malias -mptx=6.3" } */
> +
> +int v;
> +
> +void __f ()
> +{
> + v = 1;
> +}
> +
> +void f () __attribute__ ((alias ("__f")));
> +
> +int
> +main (void)
> +{
> + if (v != 0)
> + __builtin_abort ();
> + f ();
> + if (v != 1)
> + __builtin_abort ();
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-times "\\.alias f,__f;" 1 } } */
> +/* { dg-final { scan-assembler-times "\\.visible \\.func __f;" 1 } } */
> +/* { dg-final { scan-assembler-times "\\.visible \\.func f;" 1 } } */
> diff --git a/gcc/testsuite/gcc.target/nvptx/alias-2.c b/gcc/testsuite/gcc.target/nvptx/alias-2.c
> new file mode 100644
> index 00000000000..e2dc9b1f5ac
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/nvptx/alias-2.c
> @@ -0,0 +1,13 @@
> +/* { dg-do link } */
> +/* { dg-do run { target runtime_ptx_isa_version_6_3 } } */
> +/* { dg-options "-save-temps -malias -mptx=6.3 -O2" } */
> +
> +#include "alias-1.c"
> +
> +/* Inlined, so no alias. */
> +/* { dg-final { scan-assembler-not "\\.alias.*;" } } */
> +/* { dg-final { scan-assembler-not "\\.visible \\.func f;" } } */
> +
> +/* Note static and inlined, so still there. */
> +/* { dg-final { scan-assembler-times "\\.visible \\.func __f;" 1 } } */
> +
> diff --git a/gcc/testsuite/gcc.target/nvptx/alias-3.c b/gcc/testsuite/gcc.target/nvptx/alias-3.c
> new file mode 100644
> index 00000000000..60486e50826
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/nvptx/alias-3.c
> @@ -0,0 +1,29 @@
> +/* { dg-do link } */
> +/* { dg-do run { target runtime_ptx_isa_version_6_3 } } */
> +/* { dg-options "-save-temps -malias -mptx=6.3" } */
> +
> +/* Copy of alias-1.c, with static __f and f. */
> +
> +int v;
> +
> +static void __f ()
> +{
> + v = 1;
> +}
> +
> +static void f () __attribute__ ((alias ("__f")));
> +
> +int
> +main (void)
> +{
> + if (v != 0)
> + __builtin_abort ();
> + f ();
> + if (v != 1)
> + __builtin_abort ();
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-times "\\.alias f,__f;" 1 } } */
> +/* { dg-final { scan-assembler-times "\\.func __f;" 1 } } */
> +/* { dg-final { scan-assembler-times "\\.func f;" 1 } } */
> diff --git a/gcc/testsuite/gcc.target/nvptx/alias-4.c b/gcc/testsuite/gcc.target/nvptx/alias-4.c
> new file mode 100644
> index 00000000000..956150a6b3f
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/nvptx/alias-4.c
> @@ -0,0 +1,12 @@
> +/* { dg-do link } */
> +/* { dg-do run { target runtime_ptx_isa_version_6_3 } } */
> +/* { dg-options "-save-temps -malias -mptx=6.3 -O2" } */
> +
> +#include "alias-3.c"
> +
> +/* Inlined, so no alias. */
> +/* { dg-final { scan-assembler-not "\\.alias.*;" } } */
> +/* { dg-final { scan-assembler-not "\\.func f;" } } */
> +
> +/* Static and inlined, so it's deleted. */
> +/* { dg-final { scan-assembler-not "\\.func __f;" } } */
> diff --git a/gcc/testsuite/gcc.target/nvptx/nvptx.exp b/gcc/testsuite/gcc.target/nvptx/nvptx.exp
> index 284ba41908e..e69b6d35fed 100644
> --- a/gcc/testsuite/gcc.target/nvptx/nvptx.exp
> +++ b/gcc/testsuite/gcc.target/nvptx/nvptx.exp
> @@ -25,6 +25,13 @@ if ![istarget nvptx*-*-*] then {
> # Load support procs.
> load_lib gcc-dg.exp
>
> +# Return 1 if code with -mptx=6.3 can be run.
> +proc check_effective_target_runtime_ptx_isa_version_6_3 { args } {
> + return [check_runtime run_ptx_isa_6_3 {
> + int main (void) { return 0; }
> + } "-mptx=6.3"]
> +}
> +
> # If a testcase doesn't have special options, use these.
> global DEFAULT_CFLAGS
> if ![info exists DEFAULT_CFLAGS] then {
-----------------
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From 76342a36accfe2c140a707cef9b055fe726f681a Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Thu, 14 Jul 2022 22:05:17 +0200
Subject: [PATCH] [WIP] nvptx 'TARGET_USE_LOCAL_THUNK_ALIAS_P',
'TARGET_SUPPORTS_ALIASES'
---
gcc/config/nvptx/nvptx.h | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/gcc/config/nvptx/nvptx.h b/gcc/config/nvptx/nvptx.h
index dc676dcb5fc5..b1cbe5d417ba 100644
--- a/gcc/config/nvptx/nvptx.h
+++ b/gcc/config/nvptx/nvptx.h
@@ -338,6 +338,12 @@ struct GTY(()) machine_function
#define ASM_OUTPUT_DEF_FROM_DECLS(STREAM, NAME, VALUE) \
nvptx_asm_output_def_from_decls (STREAM, NAME, VALUE)
+//TODO
+/* ..., but don't let that dummy ASM_OUTPUT_DEF definition influence other
+ macros. */
+#define TARGET_USE_LOCAL_THUNK_ALIAS_P(DECL) (!((nvptx_alias == 0 || !TARGET_PTX_6_3)))
+#define TARGET_SUPPORTS_ALIASES (!((nvptx_alias == 0 || !TARGET_PTX_6_3)))
+
#define NO_DOT_IN_LABEL
#define ASM_COMMENT_START "//"
--
2.35.1
next prev parent reply other threads:[~2022-12-02 11:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-22 13:41 Tom de Vries
2022-12-02 11:24 ` Thomas Schwinge [this message]
2023-09-12 9:02 ` nvptx 'TARGET_USE_LOCAL_THUNK_ALIAS_P', 'TARGET_SUPPORTS_ALIASES' (was: [committed][nvptx] Use .alias directive for mptx >= 6.3) Thomas Schwinge
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