| Message ID | 20230814035707.11272-4-yangyujie@loongson.cn |
|---|---|
| State | New |
| Headers | show |
| Series | [v1,1/6] LoongArch: a symmetric multilib subdir layout | expand |
On Mon, 2023-08-14 at 11:57 +0800, Yang Yujie wrote: > LoongArch processors may not support memory accesses without natural > alignments. Building libraries with -mstrict-align may help with > toolchain binary compatiblity and performance on these implementations > (e.g. Loongson 2K1000LA). I don't think it's a good idea. You should provide a configuration-time option (maybe named --with-strict-align) to make -mstrict-align the default instead, thus both the libraries and the compiled user code will be suitable for 2K1000. > With this patch, no significant performance degredation is observed on > current mainstream LoongArch processors. > > gcc/ChangeLog: > > * gcc/config/t-linux: add -mstrict-align via self_specs > when building GCC libraries. > --- > gcc/config/loongarch/t-linux | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/gcc/config/loongarch/t-linux b/gcc/config/loongarch/t-linux > index 75bb430c555..2a170d600a9 100644 > --- a/gcc/config/loongarch/t-linux > +++ b/gcc/config/loongarch/t-linux > @@ -35,6 +35,9 @@ gen_mlib_spec = $(if $(word 2,$1),\ > # clean up the result of DRIVER_SELF_SPEC to avoid conflict > lib_build_self_spec = %<march=* %<mtune=* %<mcmodel=* %<mfpu=* %<msimd=* > > +# build libraries with -mstrict-align by default > +lib_build_self_spec += -mstrict-align > + > # append user-specified build options from --with-multilib-list > lib_build_self_spec += $(foreach mlib,$(subst $(comma), ,$(TM_MULTILIB_CONFIG)),\ > $(call gen_mlib_spec,$(subst /, ,$(mlib))))
diff --git a/gcc/config/loongarch/t-linux b/gcc/config/loongarch/t-linux index 75bb430c555..2a170d600a9 100644 --- a/gcc/config/loongarch/t-linux +++ b/gcc/config/loongarch/t-linux @@ -35,6 +35,9 @@ gen_mlib_spec = $(if $(word 2,$1),\ # clean up the result of DRIVER_SELF_SPEC to avoid conflict lib_build_self_spec = %<march=* %<mtune=* %<mcmodel=* %<mfpu=* %<msimd=* +# build libraries with -mstrict-align by default +lib_build_self_spec += -mstrict-align + # append user-specified build options from --with-multilib-list lib_build_self_spec += $(foreach mlib,$(subst $(comma), ,$(TM_MULTILIB_CONFIG)),\ $(call gen_mlib_spec,$(subst /, ,$(mlib))))
LoongArch processors may not support memory accesses without natural alignments. Building libraries with -mstrict-align may help with toolchain binary compatiblity and performance on these implementations (e.g. Loongson 2K1000LA). With this patch, no significant performance degredation is observed on current mainstream LoongArch processors. gcc/ChangeLog: * gcc/config/t-linux: add -mstrict-align via self_specs when building GCC libraries. --- gcc/config/loongarch/t-linux | 3 +++ 1 file changed, 3 insertions(+)