https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111966
Bug ID: 111966
Summary: GCN '--with-arch=[...]' not considered for 'mkoffload'
default 'elf_arch'
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: openacc, openmp
Severity: normal
Priority: P3
Component: other
Assignee: unassigned at gcc dot gnu.org
Reporter: tschwinge at gcc dot gnu.org
CC: ams at gcc dot gnu.org, jules at gcc dot gnu.org
Target Milestone: ---
Target: GCN
I've noticed this issue long ago; it probably existed since commit
r11-2178-ga4f49061b6d921f72b2faf4843144f3c75f828f7 "amdgcn: Handle early debug
info in mkoffload", when GCN offloading GCC 'configure'd different from
(implicit or explicit) '--with-arch=fiji', and compiling user code without
explicit '-foffload-options=amdgcn-amdhsa=-march=[...]'. In that case, the
compiler-side default doesn't match 'gcc/config/gcn/mkoffload.cc:uint32_t
elf_arch = EF_AMDGPU_MACH_AMDGCN_GFX803;', and 'elf_arch' isn't getting
corrected by an explicit '-march'. In that case, you'll get offloading
compilation failures if debugging ('-g') is enabled, for example:
[-PASS:-]{+FAIL:+} libgomp.fortran/declare-target-1.f90 -O3 -g (test for
excess errors)
[-PASS:-]{+UNRESOLVED:+} libgomp.fortran/declare-target-1.f90 -O3 -g
[-execution test-]{+compilation failed to produce executable+}
... due to:
[...]
ld: error: incompatible mach: /tmp/cc8pa454.mkoffload.dbg.o
collect2: error: ld returned 1 exit status
gcn mkoffload: fatal error:
[...]/x86_64-pc-linux-gnu-accel-amdgcn-amdhsa-gcc returned 1 exit status
[...]
('elf_arch' is used only in 'copy_early_debug_info'.)
Not a very typical configuration that anyone but me would have used ;-) -- but
I'm reporting it now, given that as of recent commit
r14-4734-g56ed1055b2f40ac162ae8d382280ac07a33f789f "amdgcn: deprecate Fiji
device and multilib", users are more likely to run into this: the compiler-side
default is now '--with-arch=gfx900' instead of 'fiji', and generally people may
specify a specific non-'fiji' '--with-arch=[...]' (for example, together with
'--without-multilib-list'), and build their code without explicit
'-foffload-options=amdgcn-amdhsa=-march=[...]'.
We need to propagate the compiler-side default '--with-arch=[...]' into
'mkoffload' 'elf_arch' -- or change the driver to simply always pass an
explicit '-march' to 'mkoffload' (and verify that, make the default 'elf_arch'
invalid)?
