[nvptx] Ignore c++ exceptions

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.

This patch does not enable exceptions for nvptx, it merely allows c++ programs
to run correctly if they do no use exception handling.

Build and reg-tested on x86_64 with nvptx accelerator.

2018-08-02  Tom de Vries  <tdevries@suse.de>

	PR target/86660
	* common/config/nvptx/nvptx-common.c (nvptx_except_unwind_info): New
	function.  Return UI_TARGET unconditionally.
	(TARGET_EXCEPT_UNWIND_INFO): Redefine to nvptx_except_unwind_info.
	* config/nvptx/nvptx.c (TARGET_ASM_BYTE_OP): Emit commented out '.byte'.

	* testsuite/libgomp.oacc-c++/routine-1-auto.C: Remove -fno-exceptions.
	* testsuite/libgomp.oacc-c++/routine-1-template-auto.C: Same.
	* testsuite/libgomp.oacc-c++/routine-1-template-trailing-return-type.C:
	Same.
	* testsuite/libgomp.oacc-c++/routine-1-template.C: Same.
	* testsuite/libgomp.oacc-c++/routine-1-trailing-return-type.C: Same.
	* testsuite/libgomp.oacc-c-c++-common/routine-1.c: Same.

From-SVN: r263265

3 files changed, 20 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index be8ba03..4a6ef92 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2018-08-02  Tom de Vries  <tdevries@suse.de>
+
+	PR target/86660
+	* common/config/nvptx/nvptx-common.c (nvptx_except_unwind_info): New
+	function.  Return UI_TARGET unconditionally.
+	(TARGET_EXCEPT_UNWIND_INFO): Redefine to nvptx_except_unwind_info.
+	* config/nvptx/nvptx.c (TARGET_ASM_BYTE_OP): Emit commented out '.byte'.
+
 2018-08-02  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* genemit.c (print_overload_test): Fix typo.
diff --git a/gcc/common/config/nvptx/nvptx-common.c b/gcc/common/config/nvptx/nvptx-common.c
index 27a4f46..f31e069 100644
--- a/gcc/common/config/nvptx/nvptx-common.c
+++ b/gcc/common/config/nvptx/nvptx-common.c
@@ -30,10 +30,19 @@ along with GCC; see the file COPYING3.  If not see
 #include "opts.h"
 #include "flags.h"
 
+enum unwind_info_type
+nvptx_except_unwind_info (struct gcc_options *opts ATTRIBUTE_UNUSED)
+{
+  return UI_TARGET;
+}
+
 #undef TARGET_HAVE_NAMED_SECTIONS
 #define TARGET_HAVE_NAMED_SECTIONS false
 
 #undef TARGET_DEFAULT_TARGET_FLAGS
 #define TARGET_DEFAULT_TARGET_FLAGS MASK_ABI64
 
+#undef TARGET_EXCEPT_UNWIND_INFO
+#define TARGET_EXCEPT_UNWIND_INFO nvptx_except_unwind_info
+
 struct gcc_targetm_common targetm_common = TARGETM_COMMON_INITIALIZER;
diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c
index c0b0a2e..62fefda 100644
--- a/gcc/config/nvptx/nvptx.c
+++ b/gcc/config/nvptx/nvptx.c
@@ -6051,6 +6051,9 @@ 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"