This issue is similar to what a year ago I resolved for GCN in PR112669
"GCN: wrong 'LIBRARY_PATH' in presence of several different '-march=[...]' flags".
Given the current standard nvptx configuration, we get:
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -mptx=6.3
.
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -mptx=3.1
mptx-3.1
... as expected. The following, however, is not:
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -mptx=3.1 -mptx=6.3
mptx-3.1
This should print '.'.
Or, in a '--with-arch=sm_70' configuration:
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -misa=sm_70
.
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -misa=sm_30
misa-sm_30
... as expected. The following, however, are not:
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -misa=sm_30 -misa=sm_70
misa-sm_30
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -misa=sm_30 -march=sm_70
misa-sm_30
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -march=sm_30 -march=sm_70
misa-sm_30
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -march=sm_30 -misa=sm_70
misa-sm_30
These should all print '.'.
Even worse:
$ build-gcc-offload-nvptx-none/gcc/xgcc -print-multi-directory -mgomp -mptx=3.1 -mptx=_
.
This should print 'mgomp'. Otherwise, for OpenMP offloading compilation
the wrong (non-'mgomp') multilib is linked in ('.'), and linking fails
due to 'unresolved symbol __nvptx_uni'.
PR target/117916
gcc/
* config/nvptx/nvptx.opt (misa=, mptx=): Tag as 'Negative' of
themselves.
Generate code for OpenMP offloading: enables -msoft-stack and -muniform-simt.
misa=
-Target RejectNegative ToLower Joined Enum(ptx_isa) Var(ptx_isa_option) Init(PTX_ISA_unset)
+Target RejectNegative Negative(misa=) ToLower Joined Enum(ptx_isa) Var(ptx_isa_option) Init(PTX_ISA_unset)
Specify the PTX ISA target architecture to use.
march=
Enum(ptx_version) String(_) Value(PTX_VERSION_default)
mptx=
-Target RejectNegative ToLower Joined Enum(ptx_version) Var(ptx_version_option) Init(PTX_VERSION_unset)
+Target RejectNegative Negative(mptx=) ToLower Joined Enum(ptx_version) Var(ptx_version_option) Init(PTX_VERSION_unset)
Specify the PTX ISA version to use.
minit-regs=