[ was: Re: [PATCH][nvptx] Ignore c++ exceptions ] On Thu, Aug 02, 2018 at 06:10:50PM +0200, Tom de Vries wrote: > On 08/02/2018 05:39 PM, Jakub Jelinek wrote: > > On Thu, Aug 02, 2018 at 05:30:53PM +0200, Tom de Vries wrote: > >> The nvptx port can't support exceptions using sjlj, because ptx does not > >> support sjlj. However, default_except_unwind_info still returns UI_SJLJ, > >> even > >> even if we configure with --disable-sjlj-exceptions, because UI_SJLJ is the > >> fallback option. > >> > >> The reason default_except_unwind_info doesn't return UI_DWARF2 is because > >> DWARF2_UNWIND_INFO is not defined in defaults.h, because > >> INCOMING_RETURN_ADDR_RTX is not defined, because there's no ptx equivalent. > >> > >> Testcase libgomp.c++/for-15.C currently doesn't compile unless > >> fno-exceptions > >> is added because: > >> - it tries to generate sjlj exception handling code, and > >> - it tries to generate exception tables using label-addressed .byte > >> sequence. > >> Ptx doesn't support generating random data at a label, nor being able to > >> load/write data relative to a label. > >> > >> This patch fixes the first problem by using UI_TARGET for nvptx. > >> > >> The second problem is worked around by generating all .byte sequences > >> commented > >> out. It would be better to have a narrower workaround, and define > >> TARGET_ASM_BYTE_OP to "error: .byte unsupported " or some such. > > > > Hopefully this part is temporary and there is some way to figure this out > > later. > > > > I except that for UI_NONE we don't want to write out exception tables, > so that's something we can fix, and then we can return UI_NONE in > nvptx_except_unwind_info. >
Hi, If a target does not support exceptions, it can indicate this by returning UI_NONE in TARGET_EXCEPT_UNWIND_INFO. Currently the compiler still emits exception tables for such a target. This patch makes sure that no exception tables are emitted if the target does not support exceptions. This allows us to remove a workaround in TARGET_ASM_BYTE_OP in the nvptx port. Build on x86_64 with nvptx accelerator, and tested libgomp. OK for trunk if currently running bootstrap and reg-test on x86_64 succeeds? Thanks, - Tom [c++] Don't emit exception tables for UI_NONE 2018-08-03 Tom de Vries <tdevr...@suse.de> * common/config/nvptx/nvptx-common.c (nvptx_except_unwind_info): Return UI_NONE. * config/nvptx/nvptx.c (TARGET_ASM_BYTE_OP): Remove define. * except.c (output_function_exception_table): Do early exit if targetm_common.except_unwind_info (&global_options) == UI_NONE. --- gcc/common/config/nvptx/nvptx-common.c | 2 +- gcc/config/nvptx/nvptx.c | 3 --- gcc/except.c | 3 ++- 3 files changed, 3 insertions(+), 5 deletions(-) diff --git a/gcc/common/config/nvptx/nvptx-common.c b/gcc/common/config/nvptx/nvptx-common.c index f31e0696281..3a124e8844d 100644 --- a/gcc/common/config/nvptx/nvptx-common.c +++ b/gcc/common/config/nvptx/nvptx-common.c @@ -33,7 +33,7 @@ along with GCC; see the file COPYING3. If not see enum unwind_info_type nvptx_except_unwind_info (struct gcc_options *opts ATTRIBUTE_UNUSED) { - return UI_TARGET; + return UI_NONE; } #undef TARGET_HAVE_NAMED_SECTIONS diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c index 62fefda8612..c0b0a2ec3ab 100644 --- a/gcc/config/nvptx/nvptx.c +++ b/gcc/config/nvptx/nvptx.c @@ -6051,9 +6051,6 @@ nvptx_can_change_mode_class (machine_mode, machine_mode, reg_class_t) #undef TARGET_HAVE_SPECULATION_SAFE_VALUE #define TARGET_HAVE_SPECULATION_SAFE_VALUE speculation_safe_value_not_needed -#undef TARGET_ASM_BYTE_OP -#define TARGET_ASM_BYTE_OP "// .byte " - struct gcc_target targetm = TARGET_INITIALIZER; #include "gt-nvptx.h" diff --git a/gcc/except.c b/gcc/except.c index 84666d9041e..728b1e1d349 100644 --- a/gcc/except.c +++ b/gcc/except.c @@ -3189,7 +3189,8 @@ output_function_exception_table (int section) rtx personality = get_personality_function (current_function_decl); /* Not all functions need anything. */ - if (!crtl->uses_eh_lsda) + if (!crtl->uses_eh_lsda + || targetm_common.except_unwind_info (&global_options) == UI_NONE) return; /* No need to emit any boilerplate stuff for the cold part. */