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author | Florian Weimer <fweimer@redhat.com> | 2023-01-03 16:47:32 +0100 |
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committer | Florian Weimer <fweimer@redhat.com> | 2023-01-03 16:47:32 +0100 |
commit | 8fdef16cd5d1b89359db3cd9a9768ab2d1b5081f (patch) | |
tree | 6b44cd03f6f3e33953b8768e9eedd1cd99dcf55b /libgcc/unwind-dw2.c | |
parent | 455acc43518744b89d6a795bbba5045bd228060b (diff) | |
download | gcc-8fdef16cd5d1b89359db3cd9a9768ab2d1b5081f.zip gcc-8fdef16cd5d1b89359db3cd9a9768ab2d1b5081f.tar.gz gcc-8fdef16cd5d1b89359db3cd9a9768ab2d1b5081f.tar.bz2 |
libgcc: Specialize execute_cfa_program in DWARF unwinder for alignments [redo]
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.
Diffstat (limited to 'libgcc/unwind-dw2.c')
-rw-r--r-- | libgcc/unwind-dw2.c | 319 |
1 files changed, 30 insertions, 289 deletions
diff --git a/libgcc/unwind-dw2.c b/libgcc/unwind-dw2.c index eaceace..9a3ac6c 100644 --- a/libgcc/unwind-dw2.c +++ b/libgcc/unwind-dw2.c @@ -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, ®); - 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, ®); - /* 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 = 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 = 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, ®); - insn_ptr = read_uleb128 (insn_ptr, ®2); - 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 = 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, ®); - 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, ®); - 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, ®); - 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 = 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, ®); - 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 |