From df0311e634828fdc99ca59352aef68503d631aad Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Date: Mon, 17 Jul 2017 13:36:07 +0100 Subject: include/exec/exec-all: document common exit conditions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit As a precursor to later patches attempt to come up with a more concrete wording for what each of the common exit cases would be. CC: Emilio G. Cota CC: Richard Henderson CC: Lluís Vilanova Signed-off-by: Alex Bennée Reviewed-by: Richard Henderson Message-id: 20170713141928.25419-2-alex.bennee@linaro.org Signed-off-by: Peter Maydell --- include/exec/exec-all.h | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index bf8da2a..6b6e287 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -35,11 +35,34 @@ typedef abi_ulong tb_page_addr_t; typedef ram_addr_t tb_page_addr_t; #endif -/* is_jmp field values */ +/* DisasContext is_jmp field values + * + * is_jmp starts as DISAS_NEXT. The translator will keep processing + * instructions until an exit condition is reached. If we reach the + * exit condition and is_jmp is still DISAS_NEXT (because of some + * other condition) we simply "jump" to the next address. + * The remaining exit cases are: + * + * DISAS_JUMP - Only the PC was modified dynamically (e.g computed) + * DISAS_TB_JUMP - Only the PC was modified statically (e.g. branch) + * + * In these cases as long as the PC is updated we can chain to the + * next TB either by exiting the loop or looking up the next TB via + * the loookup helper. + * + * DISAS_UPDATE - CPU State was modified dynamically + * + * This covers any other CPU state which necessities us exiting the + * TCG code to the main run-loop. Typically this includes anything + * that might change the interrupt state. + * + * Individual translators may define additional exit cases to deal + * with per-target special conditions. + */ #define DISAS_NEXT 0 /* next instruction can be analyzed */ #define DISAS_JUMP 1 /* only pc was modified dynamically */ -#define DISAS_UPDATE 2 /* cpu state was modified dynamically */ -#define DISAS_TB_JUMP 3 /* only pc was modified statically */ +#define DISAS_TB_JUMP 2 /* only pc was modified statically */ +#define DISAS_UPDATE 3 /* cpu state was modified dynamically */ #include "qemu/log.h" -- cgit v1.1