From patchwork Wed Sep 15 14:23:08 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [_eh, dawin, Version2] Allow targets to suppress epilogues in _eh frames. Date: Wed, 15 Sep 2010 04:23:08 -0000 From: IainS X-Patchwork-Id: 64829 Message-Id: <64A496AB-C878-42AD-85DE-7187118DD4AD@sandoe-acoustics.co.uk> To: Richard Henderson Cc: GCC Patches , mrs@gcc.gnu.org Hi Richard, This kinda stalled ... I guess I should have pinged it. On 17 Aug 2010, at 15:57, Richard Henderson wrote: > On 08/17/2010 06:09 AM, IainS wrote: >> heh, I guess I meant was solving the problem you noticed above a >> pre-condition of applying the patch, or should they be considered >> separate problems? > > Let's commit them as separate patches for bi-sect-ability, > Just In Case. > >> cfi->dw_cfi_opc = DW_CFA_GNU_args_size; > > Oh, that. If Darwin doesn't like that, then it's expecting the > compiler to always use -maccumulate-outgoing-args. Just make > sure that gets set by default. I suppose you'll have to do > something about the hand-full of test cases that force that > flag off. I believe that I've addressed the points made in the thread, is this now OK? I (re)-draw your attention to the fact that I've removed the unconditional setting of flag_asynchronous_unwind_tables when flag_non_call_exceptions is set in toplev.c. if this cannot be done then, perhaps, I need to return to the original idea of using a target hook to control the suppression of eh epilogues. thanks Iain ---- amended & refreshed patch: gcc: * gcc/dwarf2out.c: DW_CFA_INTERNAL_start_epilogue, CFI_T New. (struct dw_cfi_struct): Adjust type of dw_cfi_opc. (add_fde_cfi): Handle DW_CFA_INTERNAL_start_epilogue. (dwarf2out_cfi_begin_epilogue): Insert epilogue marker. (dw_cfi_oprnd1_desc): Adjust argument type. (dw_cfi_oprnd2_desc): Likewise. (output_cfi): Handle DW_CFA_INTERNAL_start_epilogue as nop. (output_cfi_directive): Likewise. (emit_cfi_or_skip_epilogue): New. (output_fde): Use emit_cfi_or_skip_epilogue. * gcc/toplev.c (process_options): Do not set flag_asynchronous_unwind_tables unless it is unset by the target. Set flag_unwind_tables for either flag_asynchronous_unwind_tables or flag_non_call_exceptions. * gcc/config/darwin.c (darwin_override_options): Warn the the target does not fully support flag_asynchronous_unwind_tables. Switch flag_unwind_tables on for flag_non_call_exceptions or flag_exceptions on darwin versions supporting _eh frames. Ensure that all table flags are switched off for kernel code. * gcc/config/i386/darwin.h (SUBTARGET_OVERRIDE_OPTIONS): New, handle making a default unwinder when none is specified by the user. testsuite: * g++.dg/eh/async-unwind1.C: Prune warning for Darwin. * g++.dg/eh/async-unwind2.C: Likewise. #ifndef DARWIN_PREFER_DWARF Index: gcc/dwarf2out.c =================================================================== --- gcc/dwarf2out.c (revision 164304) +++ gcc/dwarf2out.c (working copy) @@ -268,9 +272,17 @@ typedef union GTY(()) dw_cfi_oprnd_struct { } dw_cfi_oprnd; +/* Use the first out-of-band opcode number as a marker for the start of + epilogues. */ +#define DW_CFA_INTERNAL_start_epilogue 0x100 +#define CFI_T enum dwarf_call_frame_info + +static enum dw_cfi_oprnd_type dw_cfi_oprnd1_desc (unsigned int cfi); +static enum dw_cfi_oprnd_type dw_cfi_oprnd2_desc (unsigned int cfi); + typedef struct GTY(()) dw_cfi_struct { dw_cfi_ref dw_cfi_next; - enum dwarf_call_frame_info dw_cfi_opc; + unsigned int dw_cfi_opc; dw_cfi_oprnd GTY ((desc ("dw_cfi_oprnd1_desc (%1.dw_cfi_opc)"))) dw_cfi_oprnd1; dw_cfi_oprnd GTY ((desc ("dw_cfi_oprnd2_desc (%1.dw_cfi_opc)"))) @@ -820,9 +832,15 @@ add_fde_cfi (const char *label, dw_cfi_ref cfi) } list_head = &cie_cfi_head; - - if (dwarf2out_do_cfi_asm ()) + + if (cfi->dw_cfi_opc == DW_CFA_INTERNAL_start_epilogue) { + dw_fde_ref fde = current_fde (); + gcc_assert (fde != NULL); + list_head = &fde->dw_fde_cfi; + } + else if (dwarf2out_do_cfi_asm ()) + { if (label) { dw_fde_ref fde = current_fde (); @@ -2893,12 +2911,22 @@ dwarf2out_cfi_begin_epilogue (rtx insn) return; /* Otherwise, search forward to see if the return insn was the last - basic block of the function. If so, we don't need save/ restore. */ + basic block of the function. If so, we don't need save/restore. + However, we do mark the position so that we can skip the epilogue + in _eh frames where required. */ gcc_assert (i != NULL); i = next_real_insn (i); if (i == NULL) - return; + { + dw_cfi_ref cfi_epi_start; + /* Emit a marker for the epilogue start. */ + cfi_epi_start = new_cfi (); + cfi_epi_start->dw_cfi_opc = DW_CFA_INTERNAL_start_epilogue; + add_fde_cfi ("", cfi_epi_start); + return; + } + /* Insert the restore before that next real insn in the stream, and before a potential NOTE_INSN_EPILOGUE_BEG -- we do need these notes to be properly nested. This should be after any label or alignment. This @@ -2940,11 +2968,9 @@ dwarf2out_frame_debug_restore_state (void) } /* Describe for the GTY machinery what parts of dw_cfi_oprnd1 are used. */ -static enum dw_cfi_oprnd_type dw_cfi_oprnd1_desc - (enum dwarf_call_frame_info cfi); static enum dw_cfi_oprnd_type -dw_cfi_oprnd1_desc (enum dwarf_call_frame_info cfi) +dw_cfi_oprnd1_desc (unsigned int cfi) { switch (cfi) { @@ -2952,6 +2978,7 @@ static enum dw_cfi_oprnd_type case DW_CFA_GNU_window_save: case DW_CFA_remember_state: case DW_CFA_restore_state: + case DW_CFA_INTERNAL_start_epilogue: return dw_cfi_oprnd_unused; case DW_CFA_set_loc: @@ -2989,11 +3016,9 @@ static enum dw_cfi_oprnd_type } /* Describe for the GTY machinery what parts of dw_cfi_oprnd2 are used. */ -static enum dw_cfi_oprnd_type dw_cfi_oprnd2_desc - (enum dwarf_call_frame_info cfi); static enum dw_cfi_oprnd_type -dw_cfi_oprnd2_desc (enum dwarf_call_frame_info cfi) +dw_cfi_oprnd2_desc (unsigned int cfi) { switch (cfi) { @@ -3120,6 +3146,8 @@ output_cfi (dw_cfi_ref cfi, dw_fde_ref fde, int fo dw2_asm_output_data (1, (cfi->dw_cfi_opc | (r & 0x3f)), "DW_CFA_restore, column %#lx", r); } + else if (cfi->dw_cfi_opc == DW_CFA_INTERNAL_start_epilogue) + ; /* This is a nop. */ else { dw2_asm_output_data (1, cfi->dw_cfi_opc, @@ -3302,6 +3330,10 @@ output_cfi_directive (dw_cfi_ref cfi) cfi->dw_cfi_oprnd1.dw_cfi_offset); break; + case DW_CFA_INTERNAL_start_epilogue: + ; /* nop. */ + break; + case DW_CFA_remember_state: fprintf (asm_out_file, "\t.cfi_remember_state\n"); break; @@ -3497,6 +3529,44 @@ output_cfis (dw_cfi_ref cfi, bool do_cfi_asm, dw_f } } +/* Output cfi skipping save/restore and epilogues in _eh frames + for targets that do not want them. */ + +static dw_cfi_ref +emit_cfi_or_skip_epilogue (dw_cfi_ref cfi, dw_fde_ref fde, bool for_eh) +{ + if (for_eh + && !flag_asynchronous_unwind_tables) + { + if (cfi->dw_cfi_opc == DW_CFA_remember_state) + { + if (flag_debug_asm) + fputs (ASM_COMMENT_START"\t\t\t"ASM_COMMENT_START + " DW_CFA_remember/restore_state pair skipped\n",asm_out_file); + /* Skip to the restore, unless there's an error and we fall off + the end. */ + while (cfi->dw_cfi_next + && cfi->dw_cfi_opc != DW_CFA_restore_state) + cfi = cfi->dw_cfi_next; + return cfi; + } + if (cfi->dw_cfi_opc == DW_CFA_INTERNAL_start_epilogue) + { + if (flag_debug_asm) + fputs (ASM_COMMENT_START"\t\t\t"ASM_COMMENT_START + " DW_CFA_INTERNAL_start_epilogue\n",asm_out_file); + /* Skip to the end. */ + while (cfi->dw_cfi_next) + cfi = cfi->dw_cfi_next; + return cfi; + } + } + + /* If it's not a special case, then just carry on. */ + output_cfi (cfi, fde, for_eh); + return cfi; +} + /* Output one FDE. */ static void @@ -3612,13 +3682,13 @@ output_fde (dw_fde_ref fde, bool for_eh, bool seco fde->dw_fde_current_label = begin; if (!fde->dw_fde_switched_sections) for (cfi = fde->dw_fde_cfi; cfi != NULL; cfi = cfi->dw_cfi_next) - output_cfi (cfi, fde, for_eh); + cfi = emit_cfi_or_skip_epilogue (cfi, fde, for_eh); else if (!second) { if (fde->dw_fde_switch_cfi) for (cfi = fde->dw_fde_cfi; cfi != NULL; cfi = cfi->dw_cfi_next) { - output_cfi (cfi, fde, for_eh); + cfi = emit_cfi_or_skip_epilogue (cfi, fde, for_eh); if (cfi == fde->dw_fde_switch_cfi) break; } @@ -3626,7 +3696,6 @@ output_fde (dw_fde_ref fde, bool for_eh, bool seco else { dw_cfi_ref cfi_next = fde->dw_fde_cfi; - if (fde->dw_fde_switch_cfi) { cfi_next = fde->dw_fde_switch_cfi->dw_cfi_next; @@ -3635,7 +3704,7 @@ output_fde (dw_fde_ref fde, bool for_eh, bool seco fde->dw_fde_switch_cfi->dw_cfi_next = cfi_next; } for (cfi = cfi_next; cfi != NULL; cfi = cfi->dw_cfi_next) - output_cfi (cfi, fde, for_eh); + cfi = emit_cfi_or_skip_epilogue (cfi, fde, for_eh); } /* If we are to emit a ref/link from function bodies to their frame tables, Index: gcc/toplev.c =================================================================== --- gcc/toplev.c (revision 164304) +++ gcc/toplev.c (working copy) @@ -1881,9 +1884,9 @@ process_options (void) if (flag_rename_registers == AUTODETECT_VALUE) flag_rename_registers = flag_unroll_loops || flag_peel_loops; - if (flag_non_call_exceptions) + if (flag_non_call_exceptions && flag_asynchronous_unwind_tables == 2) flag_asynchronous_unwind_tables = 1; - if (flag_asynchronous_unwind_tables) + if (flag_asynchronous_unwind_tables || flag_non_call_exceptions) flag_unwind_tables = 1; if (flag_value_profile_transformations) Index: gcc/testsuite/g++.dg/eh/async-unwind2.C =================================================================== --- gcc/testsuite/g++.dg/eh/async-unwind2.C (revision 164304) +++ gcc/testsuite/g++.dg/eh/async-unwind2.C (working copy) @@ -2,6 +2,7 @@ // { dg-do run { target { { i?86-*-* x86_64-*-* } && ilp32 } } } // { dg-require-effective-target fpic } // { dg-options "-Os -fasynchronous-unwind-tables -fpic -fno-inline" } +// { dg-warning "this architecture does not fully support" "" { target *-*-darwin* } 0 } #include Index: gcc/testsuite/g++.dg/eh/async-unwind1.C =================================================================== --- gcc/testsuite/g++.dg/eh/async-unwind1.C (revision 164304) +++ gcc/testsuite/g++.dg/eh/async-unwind1.C (working copy) @@ -1,6 +1,7 @@ // PR rtl-optimization/36419 // { dg-do run { target { { i?86-*-* x86_64-*-* } && ilp32 } } } // { dg-options "-Os -fasynchronous-unwind-tables -mpreferred-stack- boundary=4" } +// { dg-warning "this architecture does not fully support" "" { target *-*-darwin* } 0 } extern "C" void abort (); Index: gcc/config/darwin.c =================================================================== --- gcc/config/darwin.c (revision 164304) +++ gcc/config/darwin.c (working copy) @@ -1869,11 +1900,25 @@ darwin_kextabi_p (void) { void darwin_override_options (void) { + bool darwin9plus = strverscmp (darwin_macosx_version_min, "10.5") >= 0; + /* Don't emit DWARF3/4 unless specifically selected. This is a workaround for tool bugs. */ if (dwarf_strict < 0) dwarf_strict = 1; + /* Do not set asynchronous_unwinding (yet) unless the user specifically + asks, warn that it might not work (for Wall). */ + if (flag_asynchronous_unwind_tables) + { + if (flag_asynchronous_unwind_tables == 2) + flag_asynchronous_unwind_tables = 0; + else + warning (OPT_Wall, + "this architecture does not fully support" + " -fasynchronous-unwind-tables"); + } + /* Disable -freorder-blocks-and-partition for darwin_emit_unwind_label. */ if (flag_reorder_blocks_and_partition && (targetm.asm_out.emit_unwind_label == darwin_emit_unwind_label)) @@ -1885,6 +1930,10 @@ darwin_override_options (void) flag_reorder_blocks = 1; } + if (flag_non_call_exceptions == 1 + || flag_asynchronous_unwind_tables == 1) + flag_unwind_tables = 1; + if (flag_mkernel || flag_apple_kext) { /* -mkernel implies -fapple-kext for C++ */ @@ -1897,18 +1946,21 @@ darwin_override_options (void) flag_exceptions = 0; /* No -fnon-call-exceptions data in kexts. */ flag_non_call_exceptions = 0; + /* so no tables either.. */ + flag_unwind_tables = 0; + flag_asynchronous_unwind_tables = 0; /* We still need to emit branch islands for kernel context. */ darwin_emit_branch_islands = true; } + if (flag_var_tracking - && strverscmp (darwin_macosx_version_min, "10.5") >= 0 + && darwin9plus && debug_info_level >= DINFO_LEVEL_NORMAL && debug_hooks->var_location != do_nothing_debug_hooks.var_location) flag_var_tracking_uninit = 1; /* It is assumed that branch island stubs are needed for earlier systems. */ - if (darwin_macosx_version_min - && strverscmp (darwin_macosx_version_min, "10.5") < 0) + if (! darwin9plus) darwin_emit_branch_islands = true; } Index: gcc/config/i386/darwin.h =================================================================== --- gcc/config/i386/darwin.h (revision 164304) +++ gcc/config/i386/darwin.h (working copy) @@ -253,6 +253,39 @@ extern int darwin_emit_branch_islands; SUBTARGET_C_COMMON_OVERRIDE_OPTIONS; \ } while (0) +#undef SUBTARGET_OVERRIDE_OPTIONS +#define SUBTARGET_OVERRIDE_OPTIONS \ +do { \ + bool darwin9plus = strverscmp (darwin_macosx_version_min, "10.5") >= 0;\ + /* If no unwind model is set, then decide on a default based \ + on Darwin rev. */ \ + if (flag_omit_frame_pointer >= 1 && flag_unwind_tables == 0) \ + { \ + if (darwin9plus) \ + flag_unwind_tables = 1; /* Emit Unwind tables. */ \ + else \ + { \ + /* The user has asked to omit fp - emit Unwind tables. */ \ + if (flag_omit_frame_pointer == 1) \ + flag_unwind_tables = 1; \ + else \ + flag_omit_frame_pointer = 0;/* Use the frame pointer. */ \ + } \ + } \ + /* Default frame pointers on for earlier versions of Darwin. */ \ + if (flag_omit_frame_pointer == 2 && !darwin9plus) \ + flag_omit_frame_pointer = 0; \ + /* Do not set asynchronous_unwinding (yet) unless the user \ + specifically asks. */ \ + if (flag_asynchronous_unwind_tables == 2) \ + flag_asynchronous_unwind_tables = 0; \ + /* Jam this on to avoid a GNU-specific dwarf opcodeup setting \ + Darwin10's eh frame compacter. */ \ + if (flag_exceptions || flag_asynchronous_unwind_tables \ + || flag_unwind_tables) \ + target_flags |= MASK_ACCUMULATE_OUTGOING_ARGS; \ +} while (0) + /* Darwin on x86_64 uses dwarf-2 by default. Pre-darwin9 32-bit compiles default to stabs+. darwin9+ defaults to dwarf-2. */