| Message ID | 20210622171443.1287801-3-abidh@codesourcery.com |
|---|---|
| State | New |
| Headers | show |
| Series | Improve debug support. | expand |
On 22/06/2021 18:14, Hafiz Abid Qadeer wrote: > As size of address is bigger than registers in amdgcn, we are forced to use > DW_CFA_def_cfa_expression to make an expression that concatenates multiple > registers for the value of the CFA. This then prohibits us from using many > of the dwarf ops which expect CFA rule to be a single regsiter plus an offset. > Using frame pointer in the CFA rule is only real possibility as it is saved > in every frame and it is easy to unwind its value. > > So unless user gives fomit-frame-pointer, we use frame pointer for the > cfi information. This options also has a different default now. > > gcc/ > > * common/config/gcn/gcn-common.c > (gcn_option_optimization_table): Change OPT_fomit_frame_pointer to -O3. > (gcn_expand_prologue): Prefer the frame pointer when emitting CFI. > (gcn_frame_pointer_rqd): New function. > (TARGET_FRAME_POINTER_REQUIRED): New hook. > --- > gcc/common/config/gcn/gcn-common.c | 2 +- > gcc/config/gcn/gcn.c | 60 +++++++++++++++++++++++------- > 2 files changed, 47 insertions(+), 15 deletions(-) > > diff --git a/gcc/common/config/gcn/gcn-common.c b/gcc/common/config/gcn/gcn-common.c > index 305c310f940..695eb467e34 100644 > --- a/gcc/common/config/gcn/gcn-common.c > +++ b/gcc/common/config/gcn/gcn-common.c > @@ -27,7 +27,7 @@ > /* Set default optimization options. */ > static const struct default_options gcn_option_optimization_table[] = > { > - { OPT_LEVELS_1_PLUS, OPT_fomit_frame_pointer, NULL, 1 }, > + { OPT_LEVELS_3_PLUS, OPT_fomit_frame_pointer, NULL, 1 }, > { OPT_LEVELS_NONE, 0, NULL, 0 } > }; > > diff --git a/gcc/config/gcn/gcn.c b/gcc/config/gcn/gcn.c > index 3ab16548aad..0eac3aa3844 100644 > --- a/gcc/config/gcn/gcn.c > +++ b/gcc/config/gcn/gcn.c > @@ -2900,10 +2900,14 @@ gcn_expand_prologue () > rtx adjustment = gen_int_mode (sp_adjust, SImode); > rtx insn = emit_insn (gen_addsi3_scalar_carry (sp_lo, sp_lo, > adjustment, scc)); > - RTX_FRAME_RELATED_P (insn) = 1; > - add_reg_note (insn, REG_FRAME_RELATED_EXPR, > - gen_rtx_SET (sp, > - gen_rtx_PLUS (DImode, sp, adjustment))); > + if (!offsets->need_frame_pointer) > + { > + RTX_FRAME_RELATED_P (insn) = 1; > + add_reg_note (insn, REG_FRAME_RELATED_EXPR, > + gen_rtx_SET (sp, > + gen_rtx_PLUS (DImode, sp, > + adjustment))); > + } > emit_insn (gen_addcsi3_scalar_zero (sp_hi, sp_hi, scc)); > } > > @@ -2917,25 +2921,24 @@ gcn_expand_prologue () > rtx adjustment = gen_int_mode (fp_adjust, SImode); > rtx insn = emit_insn (gen_addsi3_scalar_carry(fp_lo, sp_lo, > adjustment, scc)); > - RTX_FRAME_RELATED_P (insn) = 1; > - add_reg_note (insn, REG_FRAME_RELATED_EXPR, > - gen_rtx_SET (fp, > - gen_rtx_PLUS (DImode, sp, adjustment))); > emit_insn (gen_addcsi3_scalar (fp_hi, sp_hi, > (fp_adjust < 0 ? GEN_INT (-1) > : const0_rtx), > scc, scc)); > + > + /* Set the CFA to the entry stack address, as an offset from the > + frame pointer. This is preferred because the frame pointer is > + saved in each frame, whereas the stack pointer is not. */ > + RTX_FRAME_RELATED_P (insn) = 1; > + add_reg_note (insn, REG_CFA_DEF_CFA, > + gen_rtx_PLUS (DImode, fp, > + GEN_INT (-(offsets->pretend_size > + + offsets->callee_saves)))); > } > > rtx_insn *seq = get_insns (); > end_sequence (); > > - /* FIXME: Prologue insns should have this flag set for debug output, etc. > - but it causes issues for now. > - for (insn = seq; insn; insn = NEXT_INSN (insn)) > - if (INSN_P (insn)) > - RTX_FRAME_RELATED_P (insn) = 1;*/ > - > emit_insn (seq); > } > else > @@ -3011,6 +3014,16 @@ gcn_expand_prologue () > gen_rtx_SET (sp, gen_rtx_PLUS (DImode, sp, > dbg_adjustment))); > > + if (offsets->need_frame_pointer) > + { > + /* Set the CFA to the entry stack address, as an offset from the > + frame pointer. This is necessary when alloca is used, and > + harmless otherwise. */ > + rtx neg_adjust = gen_int_mode (-offsets->callee_saves, DImode); > + add_reg_note (insn, REG_CFA_DEF_CFA, > + gen_rtx_PLUS (DImode, fp, neg_adjust)); > + } > + > /* Make sure the flat scratch reg doesn't get optimised away. */ > emit_insn (gen_prologue_use (gen_rtx_REG (DImode, FLAT_SCRATCH_REG))); > } > @@ -3114,6 +3127,23 @@ gcn_expand_epilogue (void) > emit_jump_insn (gen_gcn_return ()); > } > > +/* Implement TARGET_FRAME_POINTER_REQUIRED. > + > + Return true if the frame pointer should not be eliminated. */ > + > +bool > +gcn_frame_pointer_rqd (void) > +{ > + /* GDB needs the frame pointer in order to unwind properly, > + but that's not important for the entry point, unless alloca is used. > + It's not important for code execution, so we should repect the > + -fomit-frame-pointer flag. */ > + return (!flag_omit_frame_pointer > + && cfun > + && (cfun->calls_alloca > + || (cfun->machine && cfun->machine->normal_function))); > +} > + > /* Implement TARGET_CAN_ELIMINATE. > > Return true if the compiler is allowed to try to replace register number > @@ -6373,6 +6403,8 @@ gcn_dwarf_register_span (rtx rtl) > #define TARGET_EMUTLS_VAR_INIT gcn_emutls_var_init > #undef TARGET_EXPAND_BUILTIN > #define TARGET_EXPAND_BUILTIN gcn_expand_builtin > +#undef TARGET_FRAME_POINTER_REQUIRED > +#define TARGET_FRAME_POINTER_REQUIRED gcn_frame_pointer_rqd > #undef TARGET_FUNCTION_ARG > #undef TARGET_FUNCTION_ARG_ADVANCE > #define TARGET_FUNCTION_ARG_ADVANCE gcn_function_arg_advance > OK. Andrew
diff --git a/gcc/common/config/gcn/gcn-common.c b/gcc/common/config/gcn/gcn-common.c index 305c310f940..695eb467e34 100644 --- a/gcc/common/config/gcn/gcn-common.c +++ b/gcc/common/config/gcn/gcn-common.c @@ -27,7 +27,7 @@ /* Set default optimization options. */ static const struct default_options gcn_option_optimization_table[] = { - { OPT_LEVELS_1_PLUS, OPT_fomit_frame_pointer, NULL, 1 }, + { OPT_LEVELS_3_PLUS, OPT_fomit_frame_pointer, NULL, 1 }, { OPT_LEVELS_NONE, 0, NULL, 0 } }; diff --git a/gcc/config/gcn/gcn.c b/gcc/config/gcn/gcn.c index 3ab16548aad..0eac3aa3844 100644 --- a/gcc/config/gcn/gcn.c +++ b/gcc/config/gcn/gcn.c @@ -2900,10 +2900,14 @@ gcn_expand_prologue () rtx adjustment = gen_int_mode (sp_adjust, SImode); rtx insn = emit_insn (gen_addsi3_scalar_carry (sp_lo, sp_lo, adjustment, scc)); - RTX_FRAME_RELATED_P (insn) = 1; - add_reg_note (insn, REG_FRAME_RELATED_EXPR, - gen_rtx_SET (sp, - gen_rtx_PLUS (DImode, sp, adjustment))); + if (!offsets->need_frame_pointer) + { + RTX_FRAME_RELATED_P (insn) = 1; + add_reg_note (insn, REG_FRAME_RELATED_EXPR, + gen_rtx_SET (sp, + gen_rtx_PLUS (DImode, sp, + adjustment))); + } emit_insn (gen_addcsi3_scalar_zero (sp_hi, sp_hi, scc)); } @@ -2917,25 +2921,24 @@ gcn_expand_prologue () rtx adjustment = gen_int_mode (fp_adjust, SImode); rtx insn = emit_insn (gen_addsi3_scalar_carry(fp_lo, sp_lo, adjustment, scc)); - RTX_FRAME_RELATED_P (insn) = 1; - add_reg_note (insn, REG_FRAME_RELATED_EXPR, - gen_rtx_SET (fp, - gen_rtx_PLUS (DImode, sp, adjustment))); emit_insn (gen_addcsi3_scalar (fp_hi, sp_hi, (fp_adjust < 0 ? GEN_INT (-1) : const0_rtx), scc, scc)); + + /* Set the CFA to the entry stack address, as an offset from the + frame pointer. This is preferred because the frame pointer is + saved in each frame, whereas the stack pointer is not. */ + RTX_FRAME_RELATED_P (insn) = 1; + add_reg_note (insn, REG_CFA_DEF_CFA, + gen_rtx_PLUS (DImode, fp, + GEN_INT (-(offsets->pretend_size + + offsets->callee_saves)))); } rtx_insn *seq = get_insns (); end_sequence (); - /* FIXME: Prologue insns should have this flag set for debug output, etc. - but it causes issues for now. - for (insn = seq; insn; insn = NEXT_INSN (insn)) - if (INSN_P (insn)) - RTX_FRAME_RELATED_P (insn) = 1;*/ - emit_insn (seq); } else @@ -3011,6 +3014,16 @@ gcn_expand_prologue () gen_rtx_SET (sp, gen_rtx_PLUS (DImode, sp, dbg_adjustment))); + if (offsets->need_frame_pointer) + { + /* Set the CFA to the entry stack address, as an offset from the + frame pointer. This is necessary when alloca is used, and + harmless otherwise. */ + rtx neg_adjust = gen_int_mode (-offsets->callee_saves, DImode); + add_reg_note (insn, REG_CFA_DEF_CFA, + gen_rtx_PLUS (DImode, fp, neg_adjust)); + } + /* Make sure the flat scratch reg doesn't get optimised away. */ emit_insn (gen_prologue_use (gen_rtx_REG (DImode, FLAT_SCRATCH_REG))); } @@ -3114,6 +3127,23 @@ gcn_expand_epilogue (void) emit_jump_insn (gen_gcn_return ()); } +/* Implement TARGET_FRAME_POINTER_REQUIRED. + + Return true if the frame pointer should not be eliminated. */ + +bool +gcn_frame_pointer_rqd (void) +{ + /* GDB needs the frame pointer in order to unwind properly, + but that's not important for the entry point, unless alloca is used. + It's not important for code execution, so we should repect the + -fomit-frame-pointer flag. */ + return (!flag_omit_frame_pointer + && cfun + && (cfun->calls_alloca + || (cfun->machine && cfun->machine->normal_function))); +} + /* Implement TARGET_CAN_ELIMINATE. Return true if the compiler is allowed to try to replace register number @@ -6373,6 +6403,8 @@ gcn_dwarf_register_span (rtx rtl) #define TARGET_EMUTLS_VAR_INIT gcn_emutls_var_init #undef TARGET_EXPAND_BUILTIN #define TARGET_EXPAND_BUILTIN gcn_expand_builtin +#undef TARGET_FRAME_POINTER_REQUIRED +#define TARGET_FRAME_POINTER_REQUIRED gcn_frame_pointer_rqd #undef TARGET_FUNCTION_ARG #undef TARGET_FUNCTION_ARG_ADVANCE #define TARGET_FUNCTION_ARG_ADVANCE gcn_function_arg_advance