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 ++ 1 file changed, 2 insertions(+) (limited to 'arm/Asm.v') 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 _ _ _ -- cgit