| Message ID | 1350973278-2236-3-git-send-email-e.voevodin@samsung.com |
|---|---|
| State | New |
| Headers | show |
On 2012-10-23 16:21, Evgeny Voevodin wrote: > We will use this pointer from functions where we don't have an > interface to pass tcg_ctx as a parameter. I don't think this is worthwhile. It'll just make the whole thing slower, passing around unnecessary pointers. r~
On 10/24/2012 01:18 AM, Richard Henderson wrote: > On 2012-10-23 16:21, Evgeny Voevodin wrote: >> We will use this pointer from functions where we don't have an >> interface to pass tcg_ctx as a parameter. > I don't think this is worthwhile. It'll just make the whole thing slower, > passing around unnecessary pointers. > > > r~ > 1. I didn't noticed any slow-down of kernel boot process. Maybe it's worth to make more tests with self modifying code but I don't think so, because 2. The most intensive usage of tcg_cur_ctx is in tcg/tcg-op.h functions. If we look carefully at them then we will see that there are only few functions for which single excessive dereferencing of a pointer leads to any significant slow-down. These functions are those which make just one or two operations and exit. And we should keep in mind that there is only single dereference of a pointer since it is stored in the register for further operations. Of course some slow-down should present but I found it negligible (actually I didn't find it at all). If there are some common tests for TCG generation speed I can try to run them and report results. Also we can specify tcg_cur_ctx as const and in that case I guess that dereferencing of tcg_cur_ctx should not lead to any slow-down. Also I can drop tcg_cur_ctx and use tcg_ctx.xxx instead as was in the first series. What about the rest patches?
diff --git a/tcg/tcg.h b/tcg/tcg.h index 43b4317..d326b36 100644 --- a/tcg/tcg.h +++ b/tcg/tcg.h @@ -431,6 +431,7 @@ struct TCGContext { }; extern TCGContext tcg_ctx; +extern TCGContext *tcg_cur_ctx; extern uint16_t *gen_opc_ptr; extern TCGArg *gen_opparam_ptr; extern uint16_t gen_opc_buf[]; diff --git a/translate-all.c b/translate-all.c index 5bd2d37..ccdcddf 100644 --- a/translate-all.c +++ b/translate-all.c @@ -32,6 +32,7 @@ /* code generation context */ TCGContext tcg_ctx; +TCGContext *tcg_cur_ctx = &tcg_ctx; uint16_t gen_opc_buf[OPC_BUF_SIZE]; TCGArg gen_opparam_buf[OPPARAM_BUF_SIZE];
We will use this pointer from functions where we don't have an interface to pass tcg_ctx as a parameter. Signed-off-by: Evgeny Voevodin <e.voevodin@samsung.com> --- tcg/tcg.h | 1 + translate-all.c | 1 + 2 files changed, 2 insertions(+)