From 591073be98300e1c07527af45c7c4ce8dff5bc39 Mon Sep 17 00:00:00 2001 From: Bernhard Schommer Date: Wed, 12 Sep 2018 14:32:01 +0200 Subject: Generate a nop instruction after some ais annotations (#137) * Generate a nop instruction after ais annotations. In order to prevent the merging of ais annotations with following Labels a nop instruction is inserted, but only if the annotation is followed immediately by a label. The insertion of nop instructions is performed during the expansion of builtin and pseudo assembler instructions and is processor independent, by inserting a __builtin_nop built-in. * Add Pnop instruction to ARM, RISC-V, and x86 ARM as well as RISC-V don't have nop instructions that can be easily encoded by for example add with zero instructions. For x86 we used to use `mov X0, X0` for nop but this may not be as efficient as the true nop instruction. * Implement __builtin_nop on all supported target architectures. This builtin is not yet made available on the C side for all architectures. Bug 24067 --- arm/Asm.v | 2 ++ arm/AsmToJSON.ml | 3 ++- arm/Asmexpand.ml | 7 +++---- arm/TargetPrinter.ml | 4 +++- 4 files changed, 10 insertions(+), 6 deletions(-) (limited to 'arm') diff --git a/arm/Asm.v b/arm/Asm.v index 07dea756..e6d1b4fc 100644 --- a/arm/Asm.v +++ b/arm/Asm.v @@ -231,6 +231,7 @@ Inductive instruction : Type := | Prev16: ireg -> ireg -> instruction (**r reverse bytes and reverse bits. *) | Prsc: ireg -> ireg -> shift_op -> instruction (**r reverse subtract without carry. *) | Psbc: ireg -> ireg -> shift_op -> instruction (**r add with carry *) + | Pnop : instruction (**r nop instruction *) (* Add, sub, rsb versions with s suffix *) | Padds: ireg -> ireg -> shift_op -> instruction (**r integer addition with update of condition flags *) | Psubs: ireg -> ireg -> shift_op -> instruction (**r integer subtraction with update of condition flags *) @@ -805,6 +806,7 @@ Definition exec_instr (f: function) (i: instruction) (rs: regset) (m: mem) : out | Pfsqrt _ _ | Prsc _ _ _ | Psbc _ _ _ + | Pnop | Padds _ _ _ | Psubs _ _ _ | Prsbs _ _ _ diff --git a/arm/AsmToJSON.ml b/arm/AsmToJSON.ml index 276ceecc..3874e141 100644 --- a/arm/AsmToJSON.ml +++ b/arm/AsmToJSON.ml @@ -30,7 +30,7 @@ let mnemonic_names = [ "Padc"; "Padd"; "Padds"; "Pand";"Pannot"; "Pasr"; "Pb"; " "Pftouizs"; "Pfuitod"; "Pfuitos"; "Pinlineasm"; "Pisb"; "Plabel"; "Pldr"; "Ploadsymbol_lbl"; "Pldr_p"; "Pldrb"; "Pldrb_p"; "Pldrh"; "Pldrh_p"; "Pldrsb"; "Pldrsh"; "Plsl"; "Plsr"; "Pmla"; "Pmov"; "Pmovite"; - "Pmovt"; "Pmovw"; "Pmul"; "Pmvn"; "Ploadsymbol_imm"; "Porr"; + "Pmovt"; "Pmovw"; "Pmul"; "Pmvn"; "Ploadsymbol_imm"; "Pnop"; "Porr"; "Ppush"; "Prev"; "Prev16"; "Prsb"; "Prsbs"; "Prsc"; "Psbc"; "Psbfx"; "Psdiv"; "Psmull"; "Pstr"; "Pstr_p"; "Pstrb"; "Pstrb_p"; "Pstrh"; "Pstrh_p"; "Psub"; "Psubs"; "Pudiv"; "Pumull" ] @@ -263,6 +263,7 @@ let pp_instructions pp ic = | Pmovw(r1, n) -> instruction pp "Pmovw" [Ireg r1; Long n] | Pmul(r1, r2, r3) -> instruction pp "Pmul" [Ireg r1; Ireg r2; Ireg r3] | Pmvn(r1, so) -> instruction pp "Pmvn" [Ireg r1; Shift so] + | Pnop -> instruction pp "Pnop" [] | Porr(r1, r2, so) -> instruction pp "Porr" [Ireg r1; Ireg r2; Shift so] | Ppush(rl) -> instruction pp "Ppush" (List.map (fun r -> Ireg r) rl) | Prev(r1, r2) -> instruction pp "Prev" [Ireg r1; Ireg r2] diff --git a/arm/Asmexpand.ml b/arm/Asmexpand.ml index 7c18be6b..d9424d11 100644 --- a/arm/Asmexpand.ml +++ b/arm/Asmexpand.ml @@ -404,6 +404,8 @@ let expand_builtin_inline name args res = (* Vararg stuff *) | "__builtin_va_start", [BA(IR a)], _ -> expand_builtin_va_start a + | "__builtin_nop", [], _ -> + emit Pnop (* Catch-all *) | _ -> raise (Error ("unrecognized builtin " ^ name)) @@ -665,10 +667,7 @@ let expand_function id fn = try set_current_function fn; fixup_arguments Incoming fn.fn_sig; - if !Clflags.option_g then - expand_debug id 13 preg_to_dwarf expand_instruction fn.fn_code - else - List.iter expand_instruction fn.fn_code; + expand id 13 preg_to_dwarf expand_instruction fn.fn_code; let fn = get_current_function () in let fn = Constantexpand.expand_constants fn in Errors.OK fn diff --git a/arm/TargetPrinter.ml b/arm/TargetPrinter.ml index 52d2ada6..bf37b0e4 100644 --- a/arm/TargetPrinter.ml +++ b/arm/TargetPrinter.ml @@ -306,6 +306,8 @@ struct fprintf oc " vsqrt.f64 %a, %a\n" freg f1 freg f2 | Psbc (r1,r2,sa) -> fprintf oc " sbc %a, %a, %a\n" ireg r1 ireg r2 shift_op sa + | Pnop -> + fprintf oc " nop\n" | Pstr(r1, r2, sa) | Pstr_a(r1, r2, sa) -> fprintf oc " str %a, [%a, %a]\n" ireg r1 ireg r2 shift_op sa | Pstrb(r1, r2, sa) -> @@ -463,7 +465,7 @@ struct | 1 -> let annot = annot_text preg_annot "sp" (camlstring_of_coqstring txt) args in fprintf oc "%s annotation: %S\n" comment annot | 2 -> let lbl = new_label () in - fprintf oc "%a: " label lbl; + fprintf oc "%a:\n" label lbl; AisAnnot.add_ais_annot lbl preg_annot "r13" (camlstring_of_coqstring txt) args | _ -> assert false end -- cgit