https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112669
Bug ID: 112669
Summary: GCN: wrong 'LIBRARY_PATH' in presence of several
different '-march=[...]' flags
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
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 run into a weird issue when several different '-march=[...]' flags appear.
This causes linking to fail: the linker tries to link in the wrong multilib's
libraries. This happens, for example, if the user provides '-march=[...]' for
libgomp offloading testing, but a test cases also specifies a specific
'-march=[...]'.
The problem might perhaps be in GCN multilib setup, however it doesn't seem
related to the recent changes ("amdgcn: deprecate Fiji device and multilib"),
as I'm also reproducing the issue with previous GCC release branches.
The issue -- I suppose -- boils down to:
No '-march=[...]' flag appears, default paths:
$ build-gcc-offload-amdgcn-amdhsa/gcc/xgcc -print-search-dirs | sed -n -e
"/^libraries: =/{s%[^=]\+=%%;s%$PWD%[...]%g;s%:%\n%g;p}" > default
$ cat < default
[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/
[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/
[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/../../../../../../amdgcn-amdhsa/lib/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/
[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/../../../../../../amdgcn-amdhsa/lib/
[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../amdgcn-amdhsa/lib/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/
[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../amdgcn-amdhsa/lib/
If one '-march=[...]' flag appears, we get those multilib paths prepended:
$ build-gcc-offload-amdgcn-amdhsa/gcc/xgcc -print-search-dirs -march=gfx906
| sed -n -e "/^libraries: =/{s%[^=]\+=%%;s%$PWD%[...]%g;s%:%\n%g;p}" > gfx906
$ diff -U1 default gfx906
--- default 2023-11-22 11:47:14.021018613 +0100
+++ gfx906 2023-11-22 11:47:21.856931965 +0100
@@ -1 +1,7 @@
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/gfx906/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/gfx906/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/../../../../../../amdgcn-amdhsa/lib/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/gfx906/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/../../../../../../amdgcn-amdhsa/lib/gfx906/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../amdgcn-amdhsa/lib/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/gfx906/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../amdgcn-amdhsa/lib/gfx906/
[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/
Similarly, if the same '-march=[...]' flag appears twice, we get those multilib
paths prepended:
$ build-gcc-offload-amdgcn-amdhsa/gcc/xgcc -print-search-dirs -march=gfx908
-march=gfx908 | sed -n -e "/^libraries:
=/{s%[^=]\+=%%;s%$PWD%[...]%g;s%:%\n%g;p}" > gfx908
$ diff -U1 default gfx908
--- default 2023-11-22 11:47:14.021018613 +0100
+++ gfx908 2023-11-22 11:47:34.760789347 +0100
@@ -1 +1,7 @@
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/gfx908/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/gfx908/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/../../../../../../amdgcn-amdhsa/lib/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/gfx908/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/../../../../../../amdgcn-amdhsa/lib/gfx908/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../amdgcn-amdhsa/lib/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/gfx908/
+[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../amdgcn-amdhsa/lib/gfx908/
[...]/build-gcc-offload-amdgcn-amdhsa/gcc/../lib/gcc/x86_64-pc-linux-gnu/14.0.0/accel/amdgcn-amdhsa/
However, if several different '-march=[...]' flags appear, we're back to the
default:
$ build-gcc-offload-amdgcn-amdhsa/gcc/xgcc -print-search-dirs -march=gfx906
-march=gfx908 | sed -n -e "/^libraries:
=/{s%[^=]\+=%%;s%$PWD%[...]%g;s%:%\n%g;p}" > gfx906,gfx908
$ cmp default gfx906,gfx908 && echo 'no difference'
no difference
$ build-gcc-offload-amdgcn-amdhsa/gcc/xgcc -print-search-dirs -march=gfx908
-march=gfx906 | sed -n -e "/^libraries:
=/{s%[^=]\+=%%;s%$PWD%[...]%g;s%:%\n%g;p}" > gfx908,gfx906
$ cmp default gfx908,gfx906 && echo 'no difference'
no difference
Instead, the last '-march=[...]' should win.
