Re: [PATCH][nvptx, doc] Update misa and mptx, add march and march-map
On 3/30/22 11:02, Tobias Burnus wrote:
On 30.03.22 10:03, Tom de Vries wrote:
On 3/29/22 16:47, Tobias Burnus wrote:
I think it would be useful to have additionally some wording for the
(new in GCC 12/new since today) macros,
[...]
The macro is defined also if the option is not specified, so I think
this formulation is not 100% clear in that aspect. I've reformulated
to fix that.
Fine. (It was a copy, paste + modify from elsewhere.)
Also, I took out the detail of how the value is determined, since
we're just following __CUDA_ARCH__ rather than defining our own policy.
OK. While I am not sure that it is obvious, also the example makes clear
what value to expect. Combining the two, I concur that the details
aren't required.
Any comments?
LGTM.
Tobias
PS: Regarding the sm_30 -> sm_35 change (before in this email thread).
That was not meant to be in the the .texi file, but just as item to
remember when updating the wwwdocs / gcc-12/changes.html document.
I see, I misunderstood then. FWIW, it's already added to the version in
my sandbox.
It was/is also not completely clear to me whether there is still this
CUDA 11.x issue of not supporting sm_30 (only sm_35 and higher) or not.
Thanks for reminding me of this issue.
I assume it still exists but is mitigated at
compiler-usage/libgomp-runtime-usage time as PTX ISA now defaults to 6.0
such that CUDA – but shouldn't it still see sm_30 instead of sm_35 in
this case?
If so, I think it will still show up when using either explicitly PTX
ISA 3.1 or when building GCC itself and all of the following holds:
nvptx-tools is installed, CUDA (in a too new version) is installed
(ptxas in $PATH) , and the the pending pull request nvptx-tools has not
been applied that ignores the non-explicit '--verify' when .target sm_xx
or PTX ISA .version is not supported by ptxas.
I don't think the 6.0 default has any influence (and I'll be using
-mptx=3.1 below to make sure we run into the worst-case behaviour).
Anyway, in absence of an nvptx-tools fix I committed a work-around in
the compiler:
...
#define ASM_SPEC "%{misa=*:-m %*; :-m sm_35}%{misa=sm_30:--no-verify}"
...
Note that this was before reverting back the default to sm_30, and I
probably forgot to update this spot when changing the default.
So now, there are effectively two workarounds in place.
This (implicitly using sm_30) passes:
...
$ ( PATH=$PATH:~/cuda/11.6.0/bin; ./gcc.sh ~/hello.c -c -save-temps
-Wa,--verify -mptx=3.1 )
...
because as we can see with -v, sm_35 is used to verify:
...
./build-gcc/gcc/as -m sm_35 --verify -o hello.o hello.s
...
This (explicitly using sm_30) passes:
...
$ ( PATH=$PATH:~/cuda/11.6.0/bin; ./gcc.sh ~/hello.c -c -save-temps
-march=sm_30 -mptx=3.1 )
...
because as we can see with -v, the --no-verify workaround is triggered:
...
./build-gcc/gcc/as -m sm_30 --no-verify -o hello.o hello.s
...
But that one stops working once we use an explicit -Wa,--verify:
...
$ ( PATH=$PATH:~/cuda/11.6.0/bin; ./gcc.sh ~/hello.c -c -save-temps
-Wa,--verify -march=sm_30 -mptx=3.1 )
ptxas fatal : Value 'sm_30' is not defined for option 'gpu-name'
nvptx-as: ptxas returned 255 exit status
...
So, it seems using sm_35 to verify sm_30 is the most robust workaround.
I'm currently testing attached patch.
Thanks,
- Tom[nvptx] Fix ASM_SPEC workaround for sm_30
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.
gcc/ChangeLog:
2022-03-30 Tom de Vries
* 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 75ac7a666b13..3b06f33032fd 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 %*"\
+
Re: [PATCH][nvptx, doc] Update misa and mptx, add march and march-map
On 30.03.22 10:03, Tom de Vries wrote: On 3/29/22 16:47, Tobias Burnus wrote: I think it would be useful to have additionally some wording for the (new in GCC 12/new since today) macros, [...] The macro is defined also if the option is not specified, so I think this formulation is not 100% clear in that aspect. I've reformulated to fix that. Fine. (It was a copy, paste + modify from elsewhere.) Also, I took out the detail of how the value is determined, since we're just following __CUDA_ARCH__ rather than defining our own policy. OK. While I am not sure that it is obvious, also the example makes clear what value to expect. Combining the two, I concur that the details aren't required. Any comments? LGTM. Tobias PS: Regarding the sm_30 -> sm_35 change (before in this email thread). That was not meant to be in the the .texi file, but just as item to remember when updating the wwwdocs / gcc-12/changes.html document. It was/is also not completely clear to me whether there is still this CUDA 11.x issue of not supporting sm_30 (only sm_35 and higher) or not. I assume it still exists but is mitigated at compiler-usage/libgomp-runtime-usage time as PTX ISA now defaults to 6.0 such that CUDA – but shouldn't it still see sm_30 instead of sm_35 in this case? If so, I think it will still show up when using either explicitly PTX ISA 3.1 or when building GCC itself and all of the following holds: nvptx-tools is installed, CUDA (in a too new version) is installed (ptxas in $PATH) , and the the pending pull request nvptx-tools has not been applied that ignores the non-explicit '--verify' when .target sm_xx or PTX ISA .version is not supported by ptxas. - Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634 München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht München, HRB 106955
Re: [PATCH][nvptx, doc] Update misa and mptx, add march and march-map
On 3/29/22 16:47, Tobias Burnus wrote:
On 29.03.22 16:28, Tobias Burnus wrote:
On 29.03.22 15:39, Tom de Vries wrote:
Any comments?
I think it would be useful to have additionally some wording for the
(new in GCC 12/new since today) macros,
Agreed.
i.e. something like:
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -27546,6 +27546,10 @@
strings must be lower-case. Valid ISA strings include @samp{sm_30} and
@samp{sm_35}. The default ISA is sm_35.
+This option causes the preprocessor macro @code{__PTX_SM__} to be defined
+to the architecture number multiplied by ten; for instance, for
+@samp{sm_35}, it has the value @samp{350}.
+
The macro is defined also if the option is not specified, so I think
this formulation is not 100% clear in that aspect. I've reformulated to
fix that.
Also, I took out the detail of how the value is determined, since we're
just following __CUDA_ARCH__ rather than defining our own policy.
@item -mptx=@var{version-string}
@opindex mptx
Generate code for given the specified PTX version (e.g.@: @samp{7.0}).
@@ -27553,6 +27557,10 @@
@samp{7.0}. The default PTX version is 6.0, unless a higher minimal
version is required for specified PTX ISA via option @option{-misa=}.
+This option causes the preprocessor macros
@code{__PTX_ISA_VERSION_MAJOR__}
+and @code{__PTX_ISA_VERSION_MINOR__} to be defined; for instance,
+for @samp{3.1} the macros have the values @samp{3} and @samp{1},
respectively.
+
Reformulated this as well.
Any comments?
Thanks,
- Tom[nvptx, doc] Document predefined macros at march and mptx
Document predefined macros:
- __PTX_SM__ ,
- __PTX_ISA_VERSION_MAJOR__ and
- __PTX_ISA_VERSION_MINOR__ .
gcc/ChangeLog:
2022-03-29 Tom de Vries
* doc/invoke.texi (march): Document __PTX_SM__.
(mptx): Document __PTX_ISA_VERSION_MAJOR__ and
__PTX_ISA_VERSION_MINOR__.
Co-Authored-By: Tobias Burnus
---
gcc/doc/invoke.texi | 9 +
1 file changed, 9 insertions(+)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 43b75132c91b..09715a510b4d 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -27547,6 +27547,10 @@ Generate code for the specified PTX ISA target architecture
@samp{sm_35}, @samp{sm_53}, @samp{sm_70}, @samp{sm_75} and
@samp{sm_80}. The default target architecture is sm_30.
+This option sets the value of the preprocessor macro
+@code{__PTX_SM__}; for instance, for @samp{sm_35}, it has the value
+@samp{350}.
+
@item -misa=@var{architecture-string}
@opindex misa
Alias of @option{-march=}.
@@ -27566,6 +27570,11 @@ Valid version strings include @samp{3.1}, @samp{6.0}, @samp{6.3}, and
version is required for specified PTX ISA target architecture via
option @option{-march=}.
+This option sets the values of the preprocessor macros
+@code{__PTX_ISA_VERSION_MAJOR__} and @code{__PTX_ISA_VERSION_MINOR__};
+for instance, for @samp{3.1} the macros have the values @samp{3} and
+@samp{1}, respectively.
+
@item -mmainkernel
@opindex mmainkernel
Link in code for a __main kernel. This is for stand-alone instead of
Re: [PATCH][nvptx, doc] Update misa and mptx, add march and march-map
On 3/29/22 16:28, Tobias Burnus wrote:
Hi Tom,
On 29.03.22 15:39, Tom de Vries wrote:
Any comments?
+(e.g.@: @samp{sm_35}). Valid architecture strings are @samp{sm_30},
+@samp{sm_35}, @samp{sm_53} @samp{sm_70}, @samp{sm_75} and
+@samp{sm_80}. The default target architecture is sm_30.
Missing comma (",") between sm_53 and sm_70.
Ack, fixed.
I want to note that the default is now back at sm_30;
for GCC 11 it was changed to sm_35, cf.
https://gcc.gnu.org/gcc-11/changes.html
I think changes are better described in release notes.
(We also need to update the wwwdocs release notes before the release,
but it
can also be done after branching).
Right, I'll follow up on your proposal from beginning of this month.
+@item -march-map=@var{architecture-string}
+@opindex march
+Select the closest available @option{-march=} value that is not more
+capable. For instance, for @option{-march-map=sm_50} select
+@option{-march=sm_35}, and for @option{-march-map=sm_53} select
+@option{-march=sm_53}.
(Somehow, I am not completely happy with the wording, but, admittedly, I
don't have a better suggestion.)
I feel the same, so committed as is.
Thanks,
- Tom
Re: [PATCH][nvptx, doc] Update misa and mptx, add march and march-map
On 29.03.22 16:28, Tobias Burnus wrote:
On 29.03.22 15:39, Tom de Vries wrote:
Any comments?
I think it would be useful to have additionally some wording for the
(new in GCC 12/new since today) macros, i.e. something like:
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -27546,6 +27546,10 @@
strings must be lower-case. Valid ISA strings include @samp{sm_30} and
@samp{sm_35}. The default ISA is sm_35.
+This option causes the preprocessor macro @code{__PTX_SM__} to be defined
+to the architecture number multiplied by ten; for instance, for
+@samp{sm_35}, it has the value @samp{350}.
+
@item -mptx=@var{version-string}
@opindex mptx
Generate code for given the specified PTX version (e.g.@: @samp{7.0}).
@@ -27553,6 +27557,10 @@
@samp{7.0}. The default PTX version is 6.0, unless a higher minimal
version is required for specified PTX ISA via option @option{-misa=}.
+This option causes the preprocessor macros @code{__PTX_ISA_VERSION_MAJOR__}
+and @code{__PTX_ISA_VERSION_MINOR__} to be defined; for instance,
+for @samp{3.1} the macros have the values @samp{3} and @samp{1}, respectively.
+
@item -mmainkernel
@opindex mmainkernel
Link in code for a __main kernel. This is for stand-alone instead of
Tobias
-
Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634
München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas
Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht
München, HRB 106955
Re: [PATCH][nvptx, doc] Update misa and mptx, add march and march-map
Hi Tom,
On 29.03.22 15:39, Tom de Vries wrote:
Any comments?
+(e.g.@: @samp{sm_35}). Valid architecture strings are @samp{sm_30},
+@samp{sm_35}, @samp{sm_53} @samp{sm_70}, @samp{sm_75} and
+@samp{sm_80}. The default target architecture is sm_30.
Missing comma (",") between sm_53 and sm_70.
I want to note that the default is now back at sm_30;
for GCC 11 it was changed to sm_35, cf. https://gcc.gnu.org/gcc-11/changes.html
(We also need to update the wwwdocs release notes before the release, but it
can also be done after branching).
+@item -march-map=@var{architecture-string}
+@opindex march
+Select the closest available @option{-march=} value that is not more
+capable. For instance, for @option{-march-map=sm_50} select
+@option{-march=sm_35}, and for @option{-march-map=sm_53} select
+@option{-march=sm_53}.
(Somehow, I am not completely happy with the wording, but, admittedly, I
don't have a better suggestion.)
Tobias
-
Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634
München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas
Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht
München, HRB 106955
[PATCH][nvptx, doc] Update misa and mptx, add march and march-map
Hi,
Update nvptx documentation:
- Use meaningful terms: "PTX ISA target architecture" and "PTX ISA version".
- Remove invalid claim that "ISA strings must be lower-case".
- Add missing sm_xx entries.
- Fix default ISA.
- Add march, copying misa doc.
- Declare misa an march alias.
- Add march-map.
- Fix "for given the specified" typo.
Any comments?
Thanks,
- Tom
[nvptx, doc] Update misa and mptx, add march and march-map
gcc/ChangeLog:
2022-03-29 Tom de Vries
* doc/invoke.texi (misa, mptx): Update.
(march, march-map): Add.
---
gcc/doc/invoke.texi | 27 ---
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 554e04ecbf3a..eb2fe959e600 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -27540,18 +27540,31 @@ These options are defined for Nvidia PTX:
Ignored, but preserved for backward compatibility. Only 64-bit ABI is
supported.
-@item -misa=@var{ISA-string}
+@item -march=@var{architecture-string}
@opindex march
-Generate code for given the specified PTX ISA (e.g.@: @samp{sm_35}). ISA
-strings must be lower-case. Valid ISA strings include @samp{sm_30} and
-@samp{sm_35}. The default ISA is sm_35.
+Generate code for the specified PTX ISA target architecture
+(e.g.@: @samp{sm_35}). Valid architecture strings are @samp{sm_30},
+@samp{sm_35}, @samp{sm_53} @samp{sm_70}, @samp{sm_75} and
+@samp{sm_80}. The default target architecture is sm_30.
+
+@item -misa=@var{architecture-string}
+@opindex misa
+Alias of @option{-march=}.
+
+@item -march-map=@var{architecture-string}
+@opindex march
+Select the closest available @option{-march=} value that is not more
+capable. For instance, for @option{-march-map=sm_50} select
+@option{-march=sm_35}, and for @option{-march-map=sm_53} select
+@option{-march=sm_53}.
@item -mptx=@var{version-string}
@opindex mptx
-Generate code for given the specified PTX version (e.g.@: @samp{7.0}).
+Generate code for the specified PTX ISA version (e.g.@: @samp{7.0}).
Valid version strings include @samp{3.1}, @samp{6.0}, @samp{6.3}, and
-@samp{7.0}. The default PTX version is 6.0, unless a higher minimal
-version is required for specified PTX ISA via option @option{-misa=}.
+@samp{7.0}. The default PTX version is 6.0, unless a higher version
+is required for specified PTX ISA target architecture via option
+@option{-march=}.
@item -mmainkernel
@opindex mmainkernel
