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| author | Bernhard Schommer <bschommer@users.noreply.github.com> | 2018-09-12 14:32:01 +0200 |
|---|---|---|
| committer | Xavier Leroy <xavierleroy@users.noreply.github.com> | 2018-09-12 14:32:01 +0200 |
| commit | 591073be98300e1c07527af45c7c4ce8dff5bc39 (patch) | |
| tree | 1f5143b8405b4d33a6133a7210839dab1e6eaad6 /riscV/Asm.v | |
| parent | 25ba7367a0d9391a4bea2d7685b8cfe8e304e2f8 (diff) | |
| download | compcert-kvx-591073be98300e1c07527af45c7c4ce8dff5bc39.tar.gz compcert-kvx-591073be98300e1c07527af45c7c4ce8dff5bc39.zip | |
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
Diffstat (limited to 'riscV/Asm.v')
| -rw-r--r-- | riscV/Asm.v | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/riscV/Asm.v b/riscV/Asm.v index 6d223c1d..1d8fda11 100644 --- a/riscV/Asm.v +++ b/riscV/Asm.v @@ -344,7 +344,8 @@ Inductive instruction : Type := | Ploadsi (rd: freg) (f: float32) (**r load an immediate single *) | Pbtbl (r: ireg) (tbl: list label) (**r N-way branch through a jump table *) | Pbuiltin: external_function -> list (builtin_arg preg) - -> builtin_res preg -> instruction. (**r built-in function (pseudo) *) + -> builtin_res preg -> instruction (**r built-in function (pseudo) *) + | Pnop : instruction. (**r nop instruction *) (** The pseudo-instructions are the following: @@ -985,6 +986,7 @@ Definition exec_instr (f: function) (i: instruction) (rs: regset) (m: mem) : out | Pfmsubd _ _ _ _ | Pfnmaddd _ _ _ _ | Pfnmsubd _ _ _ _ + | Pnop => Stuck end. |