diff mbox series

tcg: Introduce tcg_remove_ops_after

Message ID 20210604212747.959028-1-richard.henderson@linaro.org
State New
Headers show
Series tcg: Introduce tcg_remove_ops_after | expand

Commit Message

Richard Henderson June 4, 2021, 9:27 p.m. UTC
Introduce a function to remove everything emitted
since a given point.

Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 include/tcg/tcg.h |  1 +
 tcg/tcg.c         | 13 +++++++++++++
 2 files changed, 14 insertions(+)

-- 
2.25.1

Comments

Peter Maydell June 7, 2021, 1:51 p.m. UTC | #1
On Fri, 4 Jun 2021 at 22:27, Richard Henderson
<richard.henderson@linaro.org> wrote:
>

> Introduce a function to remove everything emitted

> since a given point.

>

> Cc: Peter Maydell <peter.maydell@linaro.org>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---

>  include/tcg/tcg.h |  1 +

>  tcg/tcg.c         | 13 +++++++++++++

>  2 files changed, 14 insertions(+)

>

> diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h

> index 74cb345308..6895246fab 100644

> --- a/include/tcg/tcg.h

> +++ b/include/tcg/tcg.h

> @@ -1081,6 +1081,7 @@ TCGOp *tcg_emit_op(TCGOpcode opc);

>  void tcg_op_remove(TCGContext *s, TCGOp *op);

>  TCGOp *tcg_op_insert_before(TCGContext *s, TCGOp *op, TCGOpcode opc);

>  TCGOp *tcg_op_insert_after(TCGContext *s, TCGOp *op, TCGOpcode opc);

> +void tcg_remove_ops_after(TCGOp *op);


A doc comment would be nice.

>  void tcg_optimize(TCGContext *s);

>

> diff --git a/tcg/tcg.c b/tcg/tcg.c

> index 0dc271aac9..262dbba1fd 100644

> --- a/tcg/tcg.c

> +++ b/tcg/tcg.c

> @@ -2649,6 +2649,19 @@ void tcg_op_remove(TCGContext *s, TCGOp *op)

>  #endif

>  }

>

> +void tcg_remove_ops_after(TCGOp *op)

> +{

> +    TCGContext *s = tcg_ctx;

> +

> +    while (true) {

> +        TCGOp *last = tcg_last_op();

> +        if (last == op) {

> +            return;

> +        }

> +        tcg_op_remove(s, last);

> +    }

> +}


This looks OK as far as TCG proper goes, but is it going to confuse
the TCG plugin infrastructure if a frontend generates a bunch of
TCG IR and then winds back the insn stream and generates something
else instead ? I see some calls from tcg/ into plugin related
functions, so I'm not sure...

thanks
-- PMM
Richard Henderson June 7, 2021, 3:22 p.m. UTC | #2
On 6/7/21 6:51 AM, Peter Maydell wrote:
>> +void tcg_remove_ops_after(TCGOp *op);

> 

> A doc comment would be nice.


Fair enough.

> This looks OK as far as TCG proper goes, but is it going to confuse

> the TCG plugin infrastructure if a frontend generates a bunch of

> TCG IR and then winds back the insn stream and generates something

> else instead ? I see some calls from tcg/ into plugin related

> functions, so I'm not sure...


Mm.  Didn't think about that Friday.  But looking now, if you wind back to 
dc->insn_start, everything will be fine.

The plugin stuff will put stuff in the stream, and then go back and 
post-process it.  But it does not record anything on the side, so if the stuff 
is no longer in the stream all's well.


r~
diff mbox series

Patch

diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h
index 74cb345308..6895246fab 100644
--- a/include/tcg/tcg.h
+++ b/include/tcg/tcg.h
@@ -1081,6 +1081,7 @@  TCGOp *tcg_emit_op(TCGOpcode opc);
 void tcg_op_remove(TCGContext *s, TCGOp *op);
 TCGOp *tcg_op_insert_before(TCGContext *s, TCGOp *op, TCGOpcode opc);
 TCGOp *tcg_op_insert_after(TCGContext *s, TCGOp *op, TCGOpcode opc);
+void tcg_remove_ops_after(TCGOp *op);
 
 void tcg_optimize(TCGContext *s);
 
diff --git a/tcg/tcg.c b/tcg/tcg.c
index 0dc271aac9..262dbba1fd 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -2649,6 +2649,19 @@  void tcg_op_remove(TCGContext *s, TCGOp *op)
 #endif
 }
 
+void tcg_remove_ops_after(TCGOp *op)
+{
+    TCGContext *s = tcg_ctx;
+
+    while (true) {
+        TCGOp *last = tcg_last_op();
+        if (last == op) {
+            return;
+        }
+        tcg_op_remove(s, last);
+    }
+}
+
 static TCGOp *tcg_op_alloc(TCGOpcode opc)
 {
     TCGContext *s = tcg_ctx;