Hi!
On 2025-11-28T14:04:59+0100, Tobias Burnus <[email protected]> wrote:
GCN: Use generic instead of specific arch for default-built multilibs
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -4084,16 +4084,17 @@ supported ISAs as multilib; use
@code{--with-multilib-list=} to tailor the built
multilibs. Note that mixing ISAs in the same binary is not supported and
gives
a linker error.
-By default, multilib support is built for @code{gfx900}, @code{gfx906},
-@code{gfx908}, @code{gfx90a}, @code{gfx90c}, @code{gfx1030}, @code{gfx1036},
-@code{gfx1100} and @code{gfx1103}. The default multilib configuration
-requires LLVM 15 or newer. LLVM 13.0.1 or LLVM 14 can be used by specifying
-a @code{--with-multilib-list=} that does not list any GFX 11 device nor
-@code{gfx1036}. At least LLVM 16 is required for @code{gfx1150} and
-@code{gfx1151}, LLVM 18 for @code{gfx942}, LLVM 19 for the generic
+By default, multilib support is built for @code{gfx908}, @code{gfx90a},
@code{gfx9-generic}, @code{gfx9-4-generic}, @code{gfx10-3-generic}, and
-@code{gfx11-generic} targets and for @code{gfx1152}, while LLVM 20 is required
-for @code{gfx950} and @code{gfx1153}.
+@code{gfx11-generic}, which covers all supported archs. The default multilib
+configuration requires LLVM 19 or newer. LLVM 13.0.1 or LLVM 14 can be used by
+specifying a @code{--with-multilib-list=} that only lists GFX9 or GFX10-3
+devices, while LLVM 15 is required for GFX 11 device and @code{gfx1036}.
+At least LLVM 16 is required for @code{gfx1150} and @code{gfx1151},
+LLVM 18 for @code{gfx942}, LLVM 19 for the generic @code{gfx9-generic},
+@code{gfx9-4-generic}, @code{gfx10-3-generic}, and @code{gfx11-generic}
+targets and for @code{gfx1152}, while LLVM 20 is required for
+@code{gfx950} and @code{gfx1153}.
gcc-16/changes.html: Update AMD GPU (gcn) for updated multilib support
--- a/htdocs/gcc-16/changes.html
+++ b/htdocs/gcc-16/changes.html
@@ -229,9 +229,25 @@ for general information.</p>
<ul>
<li>Experimental support for AMD Instinct MI300 (<code>gfx942</code>)
devices
has been added, including the generic <code>gfx9-4-generic</code> and
- mostly compatible <code>gfx950</code>. Consult GCC's
- <a href="https://gcc.gnu.org/install/specific.html#amdgcn-x-amdhsa";>
- installation notes</a> on how to enable multilib support for them.</li>
+ mostly compatible <code>gfx950</code>.</li>
+ <li>By default, the following multilibs are now built: <code>gfx908</code>,
+ <code>gfx90a</code>, <code>gfx9-generic</code>,
+ <code>gfx9-4-generic</code>, <code>gfx10-3-generic</code>, and
+ <code>gfx11-generic</code>. Multilibs for specific devices are no longer
+ built by default if a generic arch exists. Note:
+ <ul>
+ <li>When compiling for a specific arch and the multilib only exists
+ for the associated generic arch, GCC's error message suggests
+ the command-line option to do so.</li>
+ <li>Generic architectures require ROCm 6.4.0 or newer.</li>
+ <li>The new default-built set of multilibs now requires the assembler
+ and linker of LLVM 19 or newer.</li>
+ <li>Consult GCC'sm
+ <a
href="https://gcc.gnu.org/install/specific.html#amdgcn-x-amdhsa";>
+ AMD installation notes</a> and
+ <a
href="https://gcc.gnu.org/install/configure.html#:~:text=%2D%2Dwith%2Dmultilib%2Dlist";>
+ configuration notes</a> for setting the multilibs to be build.</li>
+ </ul></li>
I found that LLVM 19.1.7 (via Guix) doesn't support 'gfx9-4-generic':
[...]
checking for suffix of object files... configure: error: in
`[...]/build-gcc-offload-amdgcn-amdhsa/amdgcn-amdhsa/gfx9-4-generic/libgcc':
configure: error: cannot compute suffix of object files: cannot compile
See `config.log' for more details
make[1]: *** [Makefile:14238: configure-target-libgcc] Error 1
[...]
'gfx9-4-generic' is not a recognized processor for this target (ignoring
processor)
'gfx9-4-generic' is not a recognized processor for this target (ignoring
processor)
/tmp/cc5g6mSR.s:1:17: error: .amdgcn_target directive's target id
amdgcn-unknown-amdhsa--gfx9-4-generic does not match the specified target id
amdgcn-unknown-amdhsa--gfx000
.amdgcn_target "amdgcn-unknown-amdhsa--gfx9-4-generic"
^
[...]
Switching to LLVM 20.1.8 (via Guix), it builds.
Do we update the LLVM requirement, or change the (default) configuration?
