[committed][nvptx] Use --no-verify for sm_30

[committed][nvptx] Use --no-verify for sm_30

[Tom de Vries]

Hi,

In PR97348, we ran into the problem that recent CUDA dropped support for
sm_30, which inhibited the build when building with CUDA bin in the path,
because the nvptx-tools assembler uses CUDA's ptxas to do ptx verification.

To fix this, in gcc-11 the default sm_xx was moved from sm_30 to sm_35.

This however broke support for sm_30 boards: an executable build for sm_30
might contain sm_35 code from the libraries, which are build with the default
sm_xx (PR104758).

We want to fix this by going back to having the libraries build with sm_30, as
was the case for gcc-5 to gcc-10.  That however reintroduces the problem from
PR97348.

Deal with PR97348 in the simplest way possible: when calling the assembler for
sm_30, specify --no-verify.

This has the unfortunate effect that after fixing PR104758 by building
libraries with sm_30, the libraries are no longer verified.  This can be
improved upon by:
- adding a configure test in gcc that tests if CUDA supports sm_30, and
  if so disabling this patch
- dealing with this in nvptx-tools somehow, either:
  - detect at ptxas execution time that it doesn't support sm_30, or
  - detect this at nvptx-tool configure time.

Committed to trunk.

Thanks,
- Tom

[nvptx] Use --no-verify for sm_30

gcc/ChangeLog:

2022-03-03  Tom de Vries  <tdevries@suse.de>

	* config/nvptx/nvptx.h (ASM_SPEC): Add %{misa=sm_30:--no-verify}.

---
 gcc/config/nvptx/nvptx.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/config/nvptx/nvptx.h b/gcc/config/nvptx/nvptx.h
index 4ab412bc7d8..3ca22a595d2 100644
--- a/gcc/config/nvptx/nvptx.h
+++ b/gcc/config/nvptx/nvptx.h
@@ -32,7 +32,7 @@
 /* Default needs to be in sync with default for misa in nvptx.opt.
    We add a default here to work around a hard-coded sm_30 default in
    nvptx-as.  */
-#define ASM_SPEC "%{misa=*:-m %*; :-m sm_35}"
+#define ASM_SPEC "%{misa=*:-m %*; :-m sm_35}%{misa=sm_30:--no-verify}"
 
 #define TARGET_CPU_CPP_BUILTINS() nvptx_cpu_cpp_builtins ()
 

[committed][nvptx] Fix ASM_SPEC workaround for sm_30

[Tom de Vries]

Hi,

Newer versions of CUDA no longer support sm_30, and nvptx-tools as
currently doesn't handle that gracefully when verifying
( https://github.com/MentorEmbedded/nvptx-tools/issues/30 ).

There's a --no-verify work-around in place in ASM_SPEC, but that one doesn't
work when using -Wa,--verify on the command line.

Use a more robust workaround: verify using sm_35 when misa=sm_30 is specified
(either implicitly or explicitly).

Tested on nvptx.

Committed to trunk.

Thanks,
- Tom

[nvptx] Fix ASM_SPEC workaround for sm_30

gcc/ChangeLog:

2022-03-30  Tom de Vries  <tdevries@suse.de>

	* config/nvptx/nvptx.h (ASM_SPEC): Use "-m sm_35" for -misa=sm_30.

---
 gcc/config/nvptx/nvptx.h | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/gcc/config/nvptx/nvptx.h b/gcc/config/nvptx/nvptx.h
index 75ac7a666b1..3b06f33032f 100644
--- a/gcc/config/nvptx/nvptx.h
+++ b/gcc/config/nvptx/nvptx.h
@@ -29,10 +29,24 @@
 
 #define STARTFILE_SPEC "%{mmainkernel:crt0.o}"
 
-/* Default needs to be in sync with default for misa in nvptx.opt.
-   We add a default here to work around a hard-coded sm_30 default in
-   nvptx-as.  */
-#define ASM_SPEC "%{misa=*:-m %*; :-m sm_35}%{misa=sm_30:--no-verify}"
+/* Newer versions of CUDA no longer support sm_30, and nvptx-tools as
+   currently doesn't handle that gracefully when verifying
+   ( https://github.com/MentorEmbedded/nvptx-tools/issues/30 ).  Work around
+   this by verifying with sm_35 when having misa=sm_30 (either implicitly
+   or explicitly).  */
+#define ASM_SPEC				\
+  "%{"						\
+  /* Explict misa=sm_30.  */			\
+  "misa=sm_30:-m sm_35"				\
+  /* Separator.	 */				\
+  "; "						\
+  /* Catch-all.	 */				\
+  "misa=*:-m %*"				\
+  /* Separator.	 */				\
+  "; "						\
+  /* Implicit misa=sm_30.  */			\
+  ":-m sm_35"					\
+  "}"
 
 #define TARGET_CPU_CPP_BUILTINS() nvptx_cpu_cpp_builtins ()
 

Re: [committed][nvptx] Fix ASM_SPEC workaround for sm_30

[Thomas Schwinge]

Hi!

On 2022-03-31T09:40:47+0200, Tom de Vries via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> Newer versions of CUDA no longer support sm_30, and nvptx-tools as
> currently doesn't handle that gracefully when verifying
> ( https://github.com/MentorEmbedded/nvptx-tools/issues/30 ).

There's now <https://github.com/MentorEmbedded/nvptx-tools/pull/33>
'as: Deal with CUDA 11.0, "Support for Kepler 'sm_30' and 'sm_32'
architecture based products is dropped"' available for comment/testing.

> There's a --no-verify work-around in place in ASM_SPEC, but that one doesn't
> work when using -Wa,--verify on the command line.

With that resolved in nvptx-tools, we may then revert these GCC-level
workarounds, GCC commit bf4832d6fa817f66009f100a9cd68953062add7d
"[nvptx] Fix ASM_SPEC workaround for sm_30", and
GCC commit 12fa7641ceed9c9139e2ea7b62c11f3dc5b6f6f4
"[nvptx] Use --no-verify for sm_30".  OK to push, once nvptx-tools ready?

> Use a more robust workaround: verify using sm_35 when misa=sm_30 is specified
> (either implicitly or explicitly).

Thanks for that suggestion!


Grüße
 Thomas
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Re: [committed][nvptx] Fix ASM_SPEC workaround for sm_30

[Tom de Vries]

On 4/7/22 16:17, Thomas Schwinge wrote:
> Hi!
> 
> On 2022-03-31T09:40:47+0200, Tom de Vries via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
>> Newer versions of CUDA no longer support sm_30, and nvptx-tools as
>> currently doesn't handle that gracefully when verifying
>> ( https://github.com/MentorEmbedded/nvptx-tools/issues/30 ).
> 
> There's now <https://github.com/MentorEmbedded/nvptx-tools/pull/33>
> 'as: Deal with CUDA 11.0, "Support for Kepler 'sm_30' and 'sm_32'
> architecture based products is dropped"' available for comment/testing.
> 
>> There's a --no-verify work-around in place in ASM_SPEC, but that one doesn't
>> work when using -Wa,--verify on the command line.
> 
> With that resolved in nvptx-tools, we may then revert these GCC-level
> workarounds, GCC commit bf4832d6fa817f66009f100a9cd68953062add7d
> "[nvptx] Fix ASM_SPEC workaround for sm_30", and
> GCC commit 12fa7641ceed9c9139e2ea7b62c11f3dc5b6f6f4
> "[nvptx] Use --no-verify for sm_30".  OK to push, once nvptx-tools ready?
> 
>> Use a more robust workaround: verify using sm_35 when misa=sm_30 is specified
>> (either implicitly or explicitly).
> 
> Thanks for that suggestion!
> 

Hi,

I've tested the nvptx-tools patch in combination with a patch that 
remote ASM_SPEC, and that went fine.

[ Well apart from a new	libgomp FAIL:
...
FAIL: libgomp.oacc-fortran/private-variables.f90 
-DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 -foffload=nvptx-none  -O1 
  at line 142 (test for bogus messages, line 131)
...
but I assume that's unrelated ]

So, patch that removes ASM_SPEC pre-approved.

Thanks,
- Tom