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libgcc: Specialize execute_cfa_program in DWARF unwinder for alignments [redo]

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The parameters fs->data_align and fs->code_align always have fixed
values for a particular target in GCC-generated code.  Specialize
execute_cfa_program for these values, to avoid multiplications.

gcc/c-family/

	* c-cppbuiltin.cc (c_cpp_builtins): Define
	__LIBGCC_DWARF_CIE_DATA_ALIGNMENT__.

libgcc/

	* unwind-dw2-execute_cfa.h: New file.  Extracted from
	the execute_cfa_program function in unwind-dw2.c.
	* unwind-dw2.c (execute_cfa_program_generic): New function.
	(execute_cfa_program_specialized): Likewise.
	(execute_cfa_program): Call execute_cfa_program_specialized
	or execute_cfa_program_generic, as appropriate.
This commit is contained in:
Florian Weimer 2023-01-03 16:47:32 +01:00
parent 455acc4351
commit 8fdef16cd5
3 changed files with 355 additions and 289 deletions
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3
gcc/c-family/c-cppbuiltin.cc
View File

@ -1521,6 +1521,9 @@ c_cpp_builtins (cpp_reader *pfile)
#endif
builtin_define_with_int_value ("__LIBGCC_DWARF_FRAME_REGISTERS__",
DWARF_FRAME_REGISTERS);
builtin_define_with_int_value ("__LIBGCC_DWARF_CIE_DATA_ALIGNMENT__",
DWARF_CIE_DATA_ALIGNMENT);
#ifdef EH_RETURN_STACKADJ_RTX
cpp_define (pfile, "__LIBGCC_EH_RETURN_STACKADJ_RTX__");
#endif

322
libgcc/unwind-dw2-execute_cfa.h Normal file
View File

@ -0,0 +1,322 @@
/* DWARF2 exception handling CFA execution engine.
Copyright (C) 1997-2022 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
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/>. */
/* This file is included from unwind-dw2.c to specialize the code for certain
values of DATA_ALIGN and CODE_ALIGN. These macros must be defined prior to
including this file. */
{
struct frame_state_reg_info *unused_rs = NULL;
/* Don't allow remember/restore between CIE and FDE programs. */
fs->regs.prev = NULL;
/* The comparison with the return address uses < rather than <= because
we are only interested in the effects of code before the call; for a
noreturn function, the return address may point to unrelated code with
a different stack configuration that we are not interested in. We
assume that the call itself is unwind info-neutral; if not, or if
there are delay instructions that adjust the stack, these must be
reflected at the point immediately before the call insn.
In signal frames, return address is after last completed instruction,
so we add 1 to return address to make the comparison <=. */
while (insn_ptr < insn_end
&& fs->pc < context->ra + _Unwind_IsSignalFrame (context))
{
unsigned char insn = *insn_ptr++;
_uleb128_t reg, utmp;
_sleb128_t offset, stmp;
if ((insn & 0xc0) == DW_CFA_advance_loc)
fs->pc += (insn & 0x3f) * CODE_ALIGN;
else if ((insn & 0xc0) == DW_CFA_offset)
{
reg = insn & 0x3f;
insn_ptr = read_uleb128 (insn_ptr, &utmp);
offset = (_Unwind_Sword) utmp * DATA_ALIGN;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
}
else if ((insn & 0xc0) == DW_CFA_restore)
{
reg = insn & 0x3f;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
fs->regs.how[reg] = REG_UNSAVED;
}
else switch (insn)
{
case DW_CFA_set_loc:
{
_Unwind_Ptr pc;
insn_ptr = read_encoded_value (context, fs->fde_encoding,
insn_ptr, &pc);
fs->pc = (void *) pc;
}
break;
case DW_CFA_advance_loc1:
fs->pc += read_1u (insn_ptr) * CODE_ALIGN;
insn_ptr += 1;
break;
case DW_CFA_advance_loc2:
fs->pc += read_2u (insn_ptr) * CODE_ALIGN;
insn_ptr += 2;
break;
case DW_CFA_advance_loc4:
fs->pc += read_4u (insn_ptr) * CODE_ALIGN;
insn_ptr += 4;
break;
case DW_CFA_offset_extended:
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_uleb128 (insn_ptr, &utmp);
offset = (_Unwind_Sword) utmp * DATA_ALIGN;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
break;
case DW_CFA_restore_extended:
insn_ptr = read_uleb128 (insn_ptr, &reg);
/* FIXME, this is wrong; the CIE might have said that the
register was saved somewhere. */
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
fs->regs.how[reg] = REG_UNSAVED;
break;
case DW_CFA_same_value:
insn_ptr = read_uleb128 (insn_ptr, &reg);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
fs->regs.how[reg] = REG_UNSAVED;
break;
case DW_CFA_undefined:
insn_ptr = read_uleb128 (insn_ptr, &reg);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
fs->regs.how[reg] = REG_UNDEFINED;
break;
case DW_CFA_nop:
break;
case DW_CFA_register:
{
_uleb128_t reg2;
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_uleb128 (insn_ptr, &reg2);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_REG;
fs->regs.reg[reg].loc.reg = (_Unwind_Word)reg2;
}
}
break;
case DW_CFA_remember_state:
{
struct frame_state_reg_info *new_rs;
if (unused_rs)
{
new_rs = unused_rs;
unused_rs = unused_rs->prev;
}
else
new_rs = alloca (sizeof (struct frame_state_reg_info));
*new_rs = fs->regs;
fs->regs.prev = new_rs;
}
break;
case DW_CFA_restore_state:
{
struct frame_state_reg_info *old_rs = fs->regs.prev;
fs->regs = *old_rs;
old_rs->prev = unused_rs;
unused_rs = old_rs;
}
break;
case DW_CFA_def_cfa:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_reg = (_Unwind_Word)utmp;
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_offset = (_Unwind_Word)utmp;
fs->regs.cfa_how = CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_register:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_reg = (_Unwind_Word)utmp;
fs->regs.cfa_how = CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_offset:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_offset = utmp;
/* cfa_how deliberately not set. */
break;
case DW_CFA_def_cfa_expression:
fs->regs.cfa_exp = insn_ptr;
fs->regs.cfa_how = CFA_EXP;
insn_ptr = read_uleb128 (insn_ptr, &utmp);
insn_ptr += utmp;
break;
case DW_CFA_expression:
insn_ptr = read_uleb128 (insn_ptr, &reg);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_EXP;
fs->regs.reg[reg].loc.exp = insn_ptr;
}
insn_ptr = read_uleb128 (insn_ptr, &utmp);
insn_ptr += utmp;
break;
/* Dwarf3. */
case DW_CFA_offset_extended_sf:
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_sleb128 (insn_ptr, &stmp);
offset = stmp * DATA_ALIGN;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
break;
case DW_CFA_def_cfa_sf:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_reg = (_Unwind_Word)utmp;
insn_ptr = read_sleb128 (insn_ptr, &stmp);
fs->regs.cfa_offset = (_Unwind_Sword)stmp;
fs->regs.cfa_how = CFA_REG_OFFSET;
fs->regs.cfa_offset *= DATA_ALIGN;
break;
case DW_CFA_def_cfa_offset_sf:
insn_ptr = read_sleb128 (insn_ptr, &stmp);
fs->regs.cfa_offset = (_Unwind_Sword)stmp;
fs->regs.cfa_offset *= DATA_ALIGN;
/* cfa_how deliberately not set. */
break;
case DW_CFA_val_offset:
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_uleb128 (insn_ptr, &utmp);
offset = (_Unwind_Sword) utmp * DATA_ALIGN;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_VAL_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
break;
case DW_CFA_val_offset_sf:
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_sleb128 (insn_ptr, &stmp);
offset = stmp * DATA_ALIGN;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_VAL_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
break;
case DW_CFA_val_expression:
insn_ptr = read_uleb128 (insn_ptr, &reg);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_VAL_EXP;
fs->regs.reg[reg].loc.exp = insn_ptr;
}
insn_ptr = read_uleb128 (insn_ptr, &utmp);
insn_ptr += utmp;
break;
case DW_CFA_GNU_window_save:
#if defined (__aarch64__) && !defined (__ILP32__)
/* This CFA is multiplexed with Sparc. On AArch64 it's used to toggle
return address signing status. */
reg = DWARF_REGNUM_AARCH64_RA_STATE;
gcc_assert (fs->regs.how[reg] == REG_UNSAVED);
fs->regs.reg[reg].loc.offset ^= 1;
#else
/* ??? Hardcoded for SPARC register window configuration. */
if (__LIBGCC_DWARF_FRAME_REGISTERS__ >= 32)
for (reg = 16; reg < 32; ++reg)
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = (reg - 16) * sizeof (void *);
}
#endif
break;
case DW_CFA_GNU_args_size:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
context->args_size = (_Unwind_Word)utmp;
break;
case DW_CFA_GNU_negative_offset_extended:
/* Obsoleted by DW_CFA_offset_extended_sf, but used by
older PowerPC code. */
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_uleb128 (insn_ptr, &utmp);
offset = (_Unwind_Word) utmp * DATA_ALIGN;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = -offset;
}
break;
default:
gcc_unreachable ();
}
}
}
#undef DATA_ALIGN
#undef CODE_ALIGN

319
libgcc/unwind-dw2.c
View File

@ -947,302 +947,43 @@ execute_stack_op (const unsigned char *op_ptr, const unsigned char *op_end,
instruction sequence to decode, current register information and
CIE info, and the PC range to evaluate. */
static void __attribute__ ((__noinline__))
execute_cfa_program_generic (const unsigned char *insn_ptr,
const unsigned char *insn_end,
struct _Unwind_Context *context,
_Unwind_FrameState *fs)
{
#define DATA_ALIGN fs->data_align
#define CODE_ALIGN fs->code_align
#include "unwind-dw2-execute_cfa.h"
}
static inline void
execute_cfa_program_specialized (const unsigned char *insn_ptr,
const unsigned char *insn_end,
struct _Unwind_Context *context,
_Unwind_FrameState *fs)
{
#define DATA_ALIGN __LIBGCC_DWARF_CIE_DATA_ALIGNMENT__
/* GCC always uses 1 even on architectures with a fixed instruction
width. */
#define CODE_ALIGN 1
#include "unwind-dw2-execute_cfa.h"
}
static void
execute_cfa_program (const unsigned char *insn_ptr,
const unsigned char *insn_end,
struct _Unwind_Context *context,
_Unwind_FrameState *fs)
{
struct frame_state_reg_info *unused_rs = NULL;
/* Don't allow remember/restore between CIE and FDE programs. */
fs->regs.prev = NULL;
/* The comparison with the return address uses < rather than <= because
we are only interested in the effects of code before the call; for a
noreturn function, the return address may point to unrelated code with
a different stack configuration that we are not interested in. We
assume that the call itself is unwind info-neutral; if not, or if
there are delay instructions that adjust the stack, these must be
reflected at the point immediately before the call insn.
In signal frames, return address is after last completed instruction,
so we add 1 to return address to make the comparison <=. */
while (insn_ptr < insn_end
&& fs->pc < context->ra + _Unwind_IsSignalFrame (context))
{
unsigned char insn = *insn_ptr++;
_uleb128_t reg, utmp;
_sleb128_t offset, stmp;
if ((insn & 0xc0) == DW_CFA_advance_loc)
fs->pc += (insn & 0x3f) * fs->code_align;
else if ((insn & 0xc0) == DW_CFA_offset)
{
reg = insn & 0x3f;
insn_ptr = read_uleb128 (insn_ptr, &utmp);
offset = (_Unwind_Sword) utmp * fs->data_align;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
}
else if ((insn & 0xc0) == DW_CFA_restore)
{
reg = insn & 0x3f;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
fs->regs.how[reg] = REG_UNSAVED;
}
else switch (insn)
{
case DW_CFA_set_loc:
{
_Unwind_Ptr pc;
insn_ptr = read_encoded_value (context, fs->fde_encoding,
insn_ptr, &pc);
fs->pc = (void *) pc;
}
break;
case DW_CFA_advance_loc1:
fs->pc += read_1u (insn_ptr) * fs->code_align;
insn_ptr += 1;
break;
case DW_CFA_advance_loc2:
fs->pc += read_2u (insn_ptr) * fs->code_align;
insn_ptr += 2;
break;
case DW_CFA_advance_loc4:
fs->pc += read_4u (insn_ptr) * fs->code_align;
insn_ptr += 4;
break;
case DW_CFA_offset_extended:
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_uleb128 (insn_ptr, &utmp);
offset = (_Unwind_Sword) utmp * fs->data_align;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
break;
case DW_CFA_restore_extended:
insn_ptr = read_uleb128 (insn_ptr, &reg);
/* FIXME, this is wrong; the CIE might have said that the
register was saved somewhere. */
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
fs->regs.how[reg] = REG_UNSAVED;
break;
case DW_CFA_same_value:
insn_ptr = read_uleb128 (insn_ptr, &reg);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
fs->regs.how[reg] = REG_UNSAVED;
break;
case DW_CFA_undefined:
insn_ptr = read_uleb128 (insn_ptr, &reg);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
fs->regs.how[reg] = REG_UNDEFINED;
break;
case DW_CFA_nop:
break;
case DW_CFA_register:
{
_uleb128_t reg2;
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_uleb128 (insn_ptr, &reg2);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_REG;
fs->regs.reg[reg].loc.reg = (_Unwind_Word)reg2;
}
}
break;
case DW_CFA_remember_state:
{
struct frame_state_reg_info *new_rs;
if (unused_rs)
{
new_rs = unused_rs;
unused_rs = unused_rs->prev;
}
else
new_rs = alloca (sizeof (struct frame_state_reg_info));
*new_rs = fs->regs;
fs->regs.prev = new_rs;
}
break;
case DW_CFA_restore_state:
{
struct frame_state_reg_info *old_rs = fs->regs.prev;
fs->regs = *old_rs;
old_rs->prev = unused_rs;
unused_rs = old_rs;
}
break;
case DW_CFA_def_cfa:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_reg = (_Unwind_Word)utmp;
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_offset = (_Unwind_Word)utmp;
fs->regs.cfa_how = CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_register:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_reg = (_Unwind_Word)utmp;
fs->regs.cfa_how = CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_offset:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_offset = utmp;
/* cfa_how deliberately not set. */
break;
case DW_CFA_def_cfa_expression:
fs->regs.cfa_exp = insn_ptr;
fs->regs.cfa_how = CFA_EXP;
insn_ptr = read_uleb128 (insn_ptr, &utmp);
insn_ptr += utmp;
break;
case DW_CFA_expression:
insn_ptr = read_uleb128 (insn_ptr, &reg);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_EXP;
fs->regs.reg[reg].loc.exp = insn_ptr;
}
insn_ptr = read_uleb128 (insn_ptr, &utmp);
insn_ptr += utmp;
break;
/* Dwarf3. */
case DW_CFA_offset_extended_sf:
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_sleb128 (insn_ptr, &stmp);
offset = stmp * fs->data_align;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
break;
case DW_CFA_def_cfa_sf:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
fs->regs.cfa_reg = (_Unwind_Word)utmp;
insn_ptr = read_sleb128 (insn_ptr, &stmp);
fs->regs.cfa_offset = (_Unwind_Sword)stmp;
fs->regs.cfa_how = CFA_REG_OFFSET;
fs->regs.cfa_offset *= fs->data_align;
break;
case DW_CFA_def_cfa_offset_sf:
insn_ptr = read_sleb128 (insn_ptr, &stmp);
fs->regs.cfa_offset = (_Unwind_Sword)stmp;
fs->regs.cfa_offset *= fs->data_align;
/* cfa_how deliberately not set. */
break;
case DW_CFA_val_offset:
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_uleb128 (insn_ptr, &utmp);
offset = (_Unwind_Sword) utmp * fs->data_align;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_VAL_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
break;
case DW_CFA_val_offset_sf:
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_sleb128 (insn_ptr, &stmp);
offset = stmp * fs->data_align;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_VAL_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
break;
case DW_CFA_val_expression:
insn_ptr = read_uleb128 (insn_ptr, &reg);
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_VAL_EXP;
fs->regs.reg[reg].loc.exp = insn_ptr;
}
insn_ptr = read_uleb128 (insn_ptr, &utmp);
insn_ptr += utmp;
break;
case DW_CFA_GNU_window_save:
#if defined (__aarch64__) && !defined (__ILP32__)
/* This CFA is multiplexed with Sparc. On AArch64 it's used to toggle
return address signing status. */
reg = DWARF_REGNUM_AARCH64_RA_STATE;
gcc_assert (fs->regs.how[reg] == REG_UNSAVED);
fs->regs.reg[reg].loc.offset ^= 1;
#else
/* ??? Hardcoded for SPARC register window configuration. */
if (__LIBGCC_DWARF_FRAME_REGISTERS__ >= 32)
for (reg = 16; reg < 32; ++reg)
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = (reg - 16) * sizeof (void *);
}
#endif
break;
case DW_CFA_GNU_args_size:
insn_ptr = read_uleb128 (insn_ptr, &utmp);
context->args_size = (_Unwind_Word)utmp;
break;
case DW_CFA_GNU_negative_offset_extended:
/* Obsoleted by DW_CFA_offset_extended_sf, but used by
older PowerPC code. */
insn_ptr = read_uleb128 (insn_ptr, &reg);
insn_ptr = read_uleb128 (insn_ptr, &utmp);
offset = (_Unwind_Word) utmp * fs->data_align;
reg = DWARF_REG_TO_UNWIND_COLUMN (reg);
if (UNWIND_COLUMN_IN_RANGE (reg))
{
fs->regs.how[reg] = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = -offset;
}
break;
default:
gcc_unreachable ();
}
}
if (fs->data_align == __LIBGCC_DWARF_CIE_DATA_ALIGNMENT__
&& fs->code_align == 1)
execute_cfa_program_specialized (insn_ptr, insn_end, context, fs);
else
execute_cfa_program_generic (insn_ptr, insn_end, context, fs);
}
/* Given the _Unwind_Context CONTEXT for a stack frame, look up the FDE for
its caller and decode it into FS. This function also sets the