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Remove old x86 Directives #3948

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7281f3d
remove old directives
spiessimon Apr 25, 2025
c73e03b
update binary emitter filling code
spiessimon May 8, 2025
dd85f4f
review
spiessimon May 8, 2025
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107 changes: 2 additions & 105 deletions backend/amd64/emit.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -44,108 +44,6 @@ module ND = Asm_targets.Asm_directives_new
module S = Asm_targets.Asm_symbol
module L = Asm_targets.Asm_label

let rec to_x86_constant (c : ND.Directive.Constant.t) : X86_ast.constant =
match c with
| Signed_int i -> Const i
| Unsigned_int i -> Const (Numbers.Uint64.to_int64 i)
| This -> ConstThis
| Named_thing s ->
ConstLabel s
(* both seem to be printed directly to the buffer without any conversion*)
| Add (c1, c2) -> ConstAdd (to_x86_constant c1, to_x86_constant c2)
| Sub (c1, c2) -> ConstSub (to_x86_constant c1, to_x86_constant c2)

let to_x86_constant_with_width (c : ND.Directive.Constant_with_width.t) :
X86_ast.asm_line =
let width = ND.Directive.Constant_with_width.width_in_bytes c in
let const = ND.Directive.Constant_with_width.constant c in
let const = to_x86_constant const in
match width with
| Eight -> Byte const
(* on x86 Word is 2 bytes; warning this is not the same on Arm *)
| Sixteen -> Word const
| Thirty_two -> Long const
| Sixty_four -> Quad const

let to_x86_directive (dir : ND.Directive.t) : X86_ast.asm_line list =
let comment_lines comment =
(* CR sspies: This check is usually done in the printing function of the new
directives. Since we are skipping those at the moment (by emitting via
the X86 DSL), we do the same check here in the conversion. *)
if !Clflags.keep_asm_file && !Flambda_backend_flags.dasm_comments
then Option.to_list (Option.map (fun s -> X86_ast.Comment s) comment)
else []
in
match dir with
| Align { bytes; fill_x86_bin_emitter } ->
let data = match fill_x86_bin_emitter with Zero -> true | Nop -> false in
[X86_ast.Align (data, bytes)]
(* The [fill_x86_bin_emitter] field is currently ignored by GAS and MASM,
but used in the binary emitter. The bytes field is only converted to the
final value when printing. *)
| Bytes { str; comment } -> comment_lines comment @ [X86_ast.Bytes str]
| Comment s -> comment_lines (Some s)
| Const { constant; comment } ->
comment_lines comment @ [to_x86_constant_with_width constant]
| Direct_assignment (s, c) ->
(* We use [.set s c] for direct assignments, since it evaluates [c]
directly. The alternative, [s = c], is sensitive to relocations. *)
[X86_ast.Set (s, to_x86_constant c)]
| File { file_num = None; _ } ->
Misc.fatal_error "file directive must always carry a number on x86"
| File { file_num = Some file_num; filename } ->
[X86_ast.File (file_num, filename)]
| Global s -> [X86_ast.Global s]
| Indirect_symbol s -> [X86_ast.Indirect_symbol s]
| Loc { file_num; line; col; discriminator } ->
(* Behavior differs for negative column values. x86 will not output
anything, but new directives will output 0. *)
[X86_ast.Loc { file_num; line; col; discriminator }]
(* CR sspies: The [typ] matters only for MASM. The convention (implemented in
asm directives) is that in the text section, we use Code (NONE) and in the
data section, we use Machine_width_data (QWORD for amd64). The two will be
emitted differently by MASM. Because some code such as the frame tables
have moved from the data section to the text section (but were previously
still emitted with QUAD), using the new directives below changes this
behavior. *)
| New_label (s, Code) -> [X86_ast.NewLabel (s, NONE)]
| New_label (s, Machine_width_data) -> [X86_ast.NewLabel (s, QWORD)]
| New_line -> [X86_ast.NewLine]
| Private_extern s -> [X86_ast.Private_extern s]
| Section { names; flags; args } ->
[X86_ast.Section (names, flags, args, false)]
(* delayed for this directive is always ignored in GAS printing, and section
is not supported in binary emitter. In MASM, it only supports .text and
.data. *)
| Size (s, c) -> [X86_ast.Size (s, to_x86_constant c)]
| Sleb128 { constant; comment } ->
comment_lines comment @ [X86_ast.Sleb128 (to_x86_constant constant)]
| Space { bytes } -> [Space bytes]
| Type (n, st) ->
let typ = ND.symbol_type_to_string st in
[Type (n, typ)]
| Uleb128 { constant; comment } ->
comment_lines comment @ [X86_ast.Uleb128 (to_x86_constant constant)]
| Cfi_adjust_cfa_offset n -> [X86_ast.Cfi_adjust_cfa_offset n]
| Cfi_def_cfa_offset n -> [X86_ast.Cfi_def_cfa_offset n]
| Cfi_endproc -> [X86_ast.Cfi_endproc]
| Cfi_offset { reg; offset } -> [X86_ast.Cfi_offset (reg, offset)]
| Cfi_startproc -> [X86_ast.Cfi_startproc]
| Cfi_remember_state -> [X86_ast.Cfi_remember_state]
| Cfi_restore_state -> [X86_ast.Cfi_restore_state]
| Cfi_def_cfa_register r -> [X86_ast.Cfi_def_cfa_register r]
| Protected s -> [X86_ast.Protected s]
| Hidden s -> [X86_ast.Hidden s]
| Weak s -> [X86_ast.Weak s]
| External s -> [X86_ast.External (s, NEAR)]
(* All uses of [.extrn] use NEAR as the type. *)
| Reloc { offset; name = R_X86_64_PLT32; expr } ->
[ X86_ast.Reloc
{ offset = to_x86_constant offset;
name = R_X86_64_PLT32;
expr = to_x86_constant expr
} ]

(** Turn a Linear label into an assembly label. The section is checked against the
section tracked by [D] when emitting label definitions. *)
let label_to_asm_label (l : label) ~(section : Asm_targets.Asm_section.t) : L.t
Expand Down Expand Up @@ -348,7 +246,7 @@ let emit_named_text_section ?(suffix = "") func_name =
| _ ->
ND.switch_to_section_raw
~names:[Printf.sprintf ".text.caml.%s%s" (emit_symbol func_name) suffix]
~flags:(Some "ax") ~args:["@progbits"];
~flags:(Some "ax") ~args:["@progbits"] ~is_delayed:false;
(* Warning: We set the internal section ref to Text here, because it
currently does not supported named text sections. In the rest of this
file, we pretend the section is called Text rather than the function
Expand Down Expand Up @@ -2237,8 +2135,7 @@ let begin_assembly unix =
ND.initialize ~big_endian:Arch.big_endian
~emit_assembly_comments:!Flambda_backend_flags.dasm_comments
(* As a first step, we emit by calling the corresponding x86 emit
directives. *) ~emit:(fun d ->
List.iter directive (to_x86_directive d));
directives. *) ~emit:(fun d -> directive (Directive d));
let code_begin = Cmm_helpers.make_symbol "code_begin" in
let code_end = Cmm_helpers.make_symbol "code_end" in
Emitaux.Dwarf_helpers.begin_dwarf ~code_begin ~code_end ~file_emitter;
Expand Down
5 changes: 3 additions & 2 deletions backend/arm64/emit.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -774,7 +774,8 @@ let emit_literals p align emit_literal =
D.switch_to_section_raw
~names:["__TEXT,__literal" ^ Int.to_string align]
~flags:None
~args:[Int.to_string align ^ "byte_literals"];
~args:[Int.to_string align ^ "byte_literals"]
~is_delayed:false;
(* CR sspies: The following section is incorrect. We are in a data section
here. Fix this when cleaning up the section mechanism. *)
D.unsafe_set_internal_section_ref Text);
Expand Down Expand Up @@ -1233,7 +1234,7 @@ let emit_named_text_section func_name =
the new asm directives. *)
D.switch_to_section_raw
~names:[".text.caml." ^ S.encode (S.create func_name)]
~flags:(Some "ax") ~args:["%progbits"];
~flags:(Some "ax") ~args:["%progbits"] ~is_delayed:false;
(* Warning: We set the internal section ref to Text here, because it
currently does not supported named text sections. In the rest of this
file, we pretend the section is called Text rather than the function
Expand Down
4 changes: 2 additions & 2 deletions backend/asm_targets/asm_directives.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -135,11 +135,11 @@ module Make (A : Asm_directives_intf.Arg) : Asm_directives_intf.S = struct
()
| _ ->
current_dwarf_section_ref := Some section;
let ({ names; flags; args } : Asm_section.section_details) =
let ({ names; flags; args; is_delayed } : Asm_section.section_details) =
Asm_section.details section ~first_occurrence
in
if not first_occurrence then new_line ();
D.section ~delayed:(Asm_section.is_delayed section) names flags args;
D.section ~delayed:is_delayed names flags args;
if first_occurrence then define_label (Asm_label.for_section section)

let initialize () =
Expand Down
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