Re: [Qemu-devel] [RFC PATCH 1/3] tcg/aarch64: Introduce and use jump to register

[Richard Henderson]

On 06/07/2017 03:52 PM, Pranith Kumar wrote:

Signed-off-by: Pranith Kumar 
---
  tcg/aarch64/tcg-target.inc.c | 10 --
  1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/tcg/aarch64/tcg-target.inc.c b/tcg/aarch64/tcg-target.inc.c
index 1fa3bccc89..ab0a8caa03 100644
--- a/tcg/aarch64/tcg-target.inc.c
+++ b/tcg/aarch64/tcg-target.inc.c
@@ -819,6 +819,12 @@ static inline void tcg_out_goto(TCGContext *s, 
tcg_insn_unit *target)
  tcg_out_insn(s, 3206, B, offset);
  }
  
+static inline void tcg_out_goto_register(TCGContext *s, intptr_t target)

+{
+tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_TMP, target);
+tcg_out_insn(s, 3207, BR, TCG_REG_TMP);
+}
+
  static inline void tcg_out_goto_noaddr(TCGContext *s)
  {
  /* We pay attention here to not modify the branch target by reading from
@@ -1364,10 +1370,10 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc,
  case INDEX_op_exit_tb:
  /* Reuse the zeroing that exists for goto_ptr.  */
  if (a0 == 0) {
-tcg_out_goto(s, s->code_gen_epilogue);
+tcg_out_goto_register(s, (intptr_t)(s->code_gen_epilogue));


This pessimises the first 128MB of the buffer by not using a direct branch when 
it fits.  I think you should call the new function tcg_out_goto_long, and 
structure the function like tcg_out_call.



r~

[Qemu-devel] [RFC PATCH 1/3] tcg/aarch64: Introduce and use jump to register

[Pranith Kumar]

Signed-off-by: Pranith Kumar 
---
 tcg/aarch64/tcg-target.inc.c | 10 --
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/tcg/aarch64/tcg-target.inc.c b/tcg/aarch64/tcg-target.inc.c
index 1fa3bccc89..ab0a8caa03 100644
--- a/tcg/aarch64/tcg-target.inc.c
+++ b/tcg/aarch64/tcg-target.inc.c
@@ -819,6 +819,12 @@ static inline void tcg_out_goto(TCGContext *s, 
tcg_insn_unit *target)
 tcg_out_insn(s, 3206, B, offset);
 }
 
+static inline void tcg_out_goto_register(TCGContext *s, intptr_t target)
+{
+tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_TMP, target);
+tcg_out_insn(s, 3207, BR, TCG_REG_TMP);
+}
+
 static inline void tcg_out_goto_noaddr(TCGContext *s)
 {
 /* We pay attention here to not modify the branch target by reading from
@@ -1364,10 +1370,10 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc,
 case INDEX_op_exit_tb:
 /* Reuse the zeroing that exists for goto_ptr.  */
 if (a0 == 0) {
-tcg_out_goto(s, s->code_gen_epilogue);
+tcg_out_goto_register(s, (intptr_t)(s->code_gen_epilogue));
 } else {
 tcg_out_movi(s, TCG_TYPE_I64, TCG_REG_X0, a0);
-tcg_out_goto(s, tb_ret_addr);
+tcg_out_goto_register(s, (intptr_t)(tb_ret_addr));
 }
 break;
 
-- 
2.13.0