diff options
Diffstat (limited to 'tcg/tcg.h')
| -rw-r--r-- | tcg/tcg.h | 44 |
1 files changed, 43 insertions, 1 deletions
@@ -677,7 +677,49 @@ TCGv_i64 tcg_const_i64(int64_t val); TCGv_i32 tcg_const_local_i32(int32_t val); TCGv_i64 tcg_const_local_i64(int64_t val); -/* TCG targets may use a different definition of tcg_qemu_tb_exec. */ +/** + * tcg_qemu_tb_exec: + * @env: CPUArchState * for the CPU + * @tb_ptr: address of generated code for the TB to execute + * + * Start executing code from a given translation block. + * Where translation blocks have been linked, execution + * may proceed from the given TB into successive ones. + * Control eventually returns only when some action is needed + * from the top-level loop: either control must pass to a TB + * which has not yet been directly linked, or an asynchronous + * event such as an interrupt needs handling. + * + * The return value is a pointer to the next TB to execute + * (if known; otherwise zero). This pointer is assumed to be + * 4-aligned, and the bottom two bits are used to return further + * information: + * 0, 1: the link between this TB and the next is via the specified + * TB index (0 or 1). That is, we left the TB via (the equivalent + * of) "goto_tb <index>". The main loop uses this to determine + * how to link the TB just executed to the next. + * 2: we are using instruction counting code generation, and we + * did not start executing this TB because the instruction counter + * would hit zero midway through it. In this case the next-TB pointer + * returned is the TB we were about to execute, and the caller must + * arrange to execute the remaining count of instructions. + * + * If the bottom two bits indicate an exit-via-index then the CPU + * state is correctly synchronised and ready for execution of the next + * TB (and in particular the guest PC is the address to execute next). + * Otherwise, we gave up on execution of this TB before it started, and + * the caller must fix up the CPU state by calling cpu_pc_from_tb() + * with the next-TB pointer we return. + * + * Note that TCG targets may use a different definition of tcg_qemu_tb_exec + * to this default (which just calls the prologue.code emitted by + * tcg_target_qemu_prologue()). + */ +#define TB_EXIT_MASK 3 +#define TB_EXIT_IDX0 0 +#define TB_EXIT_IDX1 1 +#define TB_EXIT_ICOUNT_EXPIRED 2 + #if !defined(tcg_qemu_tb_exec) # define tcg_qemu_tb_exec(env, tb_ptr) \ ((tcg_target_ulong (*)(void *, void *))tcg_ctx.code_gen_prologue)(env, \ |