Re: [PATCH] hppa64-hpux: Rework EH encoding to avoid dynamic relocations

On 8/11/2026 1:38 PM, John David Anglin wrote:
> Ping.
> Dave
>
> On 2026-07-28 3:49 p.m., John David Anglin wrote:
>> Most of this change is hppa specific but we to revise the common code
>> to support ASM_OUTPUT_DWARF_TEXTREL and crtstuff.c to handle the
>> initialization of tbase for text segment relative offsets.
>>
>> Tested with no regressions on hppa64-hp-hpux11.11.
>>
>> Okay for trunk?
Given this hits dwarf2asm, it's probably best if Jakub chimes in. It 
looks like you may have tried to CC him, but got his mail address 
concatenated with mine :-)

Jakub, can you chime in here?


>>
>> Dave
>> ---
>>
>> hppa64-hpux: Rework EH encoding to avoid dynamic relocations
>>
>> The EH encoding is revised to use text segment relative offsets
>> for code labels and pc-relative offsets for data offsets.
>>
>> 2026-07-28  John David Anglin  <[email protected]>
>>
>> gcc/ChangeLog:
>>
>> 	* config/pa/pa-protos.h (pa_asm_output_dwarf_segrel): Declare.
>> 	* config/pa/pa.cc (pa_asm_output_dwarf_segrel): New.
>> 	* config/pa/pa64-hpux.h (ASM_PREFERRED_EH_DATA_FORMAT): Define.
>> 	(ASM_OUTPUT_DWARF_TEXTREL): Define.
>> 	* doc/tm.texi.in (ASM_OUTPUT_DWARF_TEXTREL): Document.
>> 	* doc/tm.texi: Regenerate.
>> 	* dwarf2asm.cc (dw2_asm_output_encoded_addr_rtx): Handle
>> 	ASM_OUTPUT_DWARF_TEXTREL.
>>
>> libgcc/ChangeLog:
>>
>> 	* config/pa/pa64-hpux-lib.h (CRT_GET_RFIB_TEXT): Define.
>> 	* crtstuff.c (crtstuff.c): Handle CRT_GET_RFIB_TEXT.
>>
>> diff --git a/gcc/config/pa/pa-protos.h b/gcc/config/pa/pa-protos.h
>> index 7fbf5750800..d7bb4663bcd 100644
>> --- a/gcc/config/pa/pa-protos.h
>> +++ b/gcc/config/pa/pa-protos.h
>> @@ -109,5 +109,7 @@ extern HOST_WIDE_INT pa_initial_elimination_offset (int, int);
>>   extern int pa_function_arg_size (machine_mode, const_tree);
>>   extern void pa_output_function_label (FILE *);
>>   extern void hppa_profile_hook (int);
>> +extern void pa_asm_output_dwarf_segrel (FILE *file, int size,
>> +					const char *label);
>>   
>>   extern const int pa_magic_milli[];
>> diff --git a/gcc/config/pa/pa.cc b/gcc/config/pa/pa.cc
>> index 0afa4c6b7c3..a6360ab96a7 100644
>> --- a/gcc/config/pa/pa.cc
>> +++ b/gcc/config/pa/pa.cc
>> @@ -11339,4 +11339,14 @@ pa_frame_pointer_required (void)
>>     return false;
>>   }
>>   
>> +/* Output a segment relative offset.  */
>> +
>> +void
>> +pa_asm_output_dwarf_segrel (FILE *file, int size, const char *label)
>> +{
>> +  fputs (integer_asm_op (size, FALSE), file);
>> +  assemble_name (file, label);
>> +  fputs("-$segrel$", file);
>> +}
>> +
>>   #include "gt-pa.h"
>> diff --git a/gcc/config/pa/pa64-hpux.h b/gcc/config/pa/pa64-hpux.h
>> index 4673a639f44..3b90c5f0a4a 100644
>> --- a/gcc/config/pa/pa64-hpux.h
>> +++ b/gcc/config/pa/pa64-hpux.h
>> @@ -376,3 +376,33 @@ do {								\
>>      __cxa_finalize introduced by crtbegin.o.  So, we provide an archive
>>      library of empty stub functions to resolve these symbols.  */
>>   #define TARGET_ATTRIBUTE_WEAK
>> +
>> +/* This macro chooses the encoding of pointers embedded in the exception
>> +   handling sections.  If at all possible, this should be defined such
>> +   that the exception handling section will not require dynamic relocations,
>> +   and so may be read-only.
>> +
>> +   The HP-UX dynamic linker can't handle unaligned DIR64 relocations.
>> +
>> +   The .eh_frame section resides in the data segment.  We use segment
>> +   relative encoding for code labels which reside in the text segment as
>> +   pc-relative offsets don't work.  Text segments are limited in size to
>> +   2G so we can use 4-byte offsets.  We use 8-byte pc-relative encoding
>> +   for data labels.  We use indirect pc-relative encoding for function
>> +   pointers.  This eliminates the need for dynamic relocations.
>> +
>> +   We use the DW_EH_PE_aligned encoding with the HP assembler but this
>> +   is never tested.  The GNU assembler is required to support many standard
>> +   C++ features.  */
>> +
>> +#undef ASM_PREFERRED_EH_DATA_FORMAT
>> +#define ASM_PREFERRED_EH_DATA_FORMAT(CODE,GLOBAL)			\
>> +  (TARGET_GAS								\
>> +   ? ((CODE) == 1							\
>> +      ? (DW_EH_PE_textrel | DW_EH_PE_sdata4)				\
>> +      : (((GLOBAL) || (CODE) == 2 ? DW_EH_PE_indirect : 0)		\
>> +	 | DW_EH_PE_pcrel | DW_EH_PE_sdata8))				\
>> +   : DW_EH_PE_aligned)
>> +
>> +#define ASM_OUTPUT_DWARF_TEXTREL(FILE,SIZE,LABEL) \
>> +  pa_asm_output_dwarf_segrel ((FILE), (SIZE), (LABEL));
>> diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
>> index 85e17525683..404bda98234 100644
>> --- a/gcc/doc/tm.texi
>> +++ b/gcc/doc/tm.texi
>> @@ -10532,6 +10532,11 @@ A C statement to issue assembly directives that create a reference to the
>>   given @var{label} relative to the dbase, using an integer of the given @var{size}.
>>   @end defmac
>>   
>> +@defmac ASM_OUTPUT_DWARF_TEXTREL (@var{stream}, @var{size}, @var{label})
>> +A C statement to issue assembly directives that create a reference to the
>> +given @var{label} relative to the tbase, using an integer of the given @var{size}.
>> +@end defmac
>> +
>>   @defmac ASM_OUTPUT_DWARF_TABLE_REF (@var{label})
>>   A C statement to issue assembly directives that create a reference to
>>   the DWARF table identifier @var{label} from the current section.  This
>> diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
>> index 1a9edd0635d..564de156702 100644
>> --- a/gcc/doc/tm.texi.in
>> +++ b/gcc/doc/tm.texi.in
>> @@ -6924,6 +6924,11 @@ A C statement to issue assembly directives that create a reference to the
>>   given @var{label} relative to the dbase, using an integer of the given @var{size}.
>>   @end defmac
>>   
>> +@defmac ASM_OUTPUT_DWARF_TEXTREL (@var{stream}, @var{size}, @var{label})
>> +A C statement to issue assembly directives that create a reference to the
>> +given @var{label} relative to the tbase, using an integer of the given @var{size}.
>> +@end defmac
>> +
>>   @defmac ASM_OUTPUT_DWARF_TABLE_REF (@var{label})
>>   A C statement to issue assembly directives that create a reference to
>>   the DWARF table identifier @var{label} from the current section.  This
>> diff --git a/gcc/dwarf2asm.cc b/gcc/dwarf2asm.cc
>> index 54d008a02be..4ec68230fea 100644
>> --- a/gcc/dwarf2asm.cc
>> +++ b/gcc/dwarf2asm.cc
>> @@ -1153,6 +1153,13 @@ dw2_asm_output_encoded_addr_rtx (int encoding, rtx addr, bool is_public,
>>   #endif
>>   	  break;
>>   
>> +#ifdef ASM_OUTPUT_DWARF_TEXTREL
>> +	case DW_EH_PE_textrel:
>> +	  gcc_assert (GET_CODE (addr) == SYMBOL_REF);
>> +	  ASM_OUTPUT_DWARF_TEXTREL (asm_out_file, size, XSTR (addr, 0));
>> +	  break;
>> +#endif
>> +
>>   	default:
>>   	  /* Other encodings should have been handled by
>>   	     ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX.  */
>> diff --git a/libgcc/config/pa/pa64-hpux-lib.h b/libgcc/config/pa/pa64-hpux-lib.h
>> index d7055e02bdc..73310493b03 100644
>> --- a/libgcc/config/pa/pa64-hpux-lib.h
>> +++ b/libgcc/config/pa/pa64-hpux-lib.h
>> @@ -23,6 +23,21 @@ a copy of the GCC Runtime Library Exception along with this program;
>>   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
>>   <http://www.gnu.org/licenses/>.  */
>>   
>> +/* Get text base.  Maximum size of the text segment is 2G, so we can
>> +   use a SEGREL32 relocation to determine segment offset.  */
>> +#define CRT_GET_RFIB_TEXT(BASE) \
>> +{									\
>> +  unsigned long tmp;							\
>> +									\
>> +  __asm__ ("bl,n L$RFIB1,%0\n\t"					\
>> +	   ".word L$RFIB1-$segrel$\n"					\
>> +	   "L$RFIB1:\n\t"						\
>> +	   "depdi 0,63,2,%0\n\t"					\
>> +	   "ldw -4(%0),%1\n\t"						\
>> +	   "sub %0,%1,%0\n"						\
>> +	   : "=&r"(BASE), "=r"(tmp));					\
>> +}
>> +
>>   /* We use DTOR_LIST_BEGIN to carry a bunch of hacks to allow us to use
>>      the init and fini array sections with both the HP and GNU linkers.
>>      The linkers setup the required dynamic entries in the dynamic segment
>> diff --git a/libgcc/crtstuff.c b/libgcc/crtstuff.c
>> index 44820cb27c1..39e7f49e9e0 100644
>> --- a/libgcc/crtstuff.c
>> +++ b/libgcc/crtstuff.c
>> @@ -475,10 +475,18 @@ frame_dummy (void)
>>   {
>>   #ifdef USE_EH_FRAME_REGISTRY
>>     static struct object object;
>> -#ifdef CRT_GET_RFIB_DATA
>> +#if defined (CRT_GET_RFIB_DATA) || defined (CRT_GET_RFIB_TEXT)
>>     void *tbase, *dbase;
>> +#ifdef CRT_GET_RFIB_TEXT
>> +  CRT_GET_RFIB_TEXT (tbase);
>> +#else
>>     tbase = 0;
>> +#endif
>> +#ifdef CRT_GET_RFIB_DATA
>>     CRT_GET_RFIB_DATA (dbase);
>> +#else
>> +  dbase = 0;
>> +#endif
>>     if (__register_frame_info_bases)
>>       __register_frame_info_bases (__EH_FRAME_BEGIN__, &object, tbase, dbase);
>>   #else
>