Re: [Qemu-devel] [PATCH v5++ 1/3] tcg/mips: implement goto_ptr

[Aurelien Jarno]

On 2017-05-02 18:21, Richard Henderson wrote:
> On 04/30/2017 04:52 PM, Aurelien Jarno wrote:
> > +/* jmp to the given host address (could be epilogue) */
> > +tcg_out_opc_reg(s, OPC_JR, 0, a0, 0);
> > +tcg_out_nop(s);
> 
> Any particular reason not to do the zeroing in the delay slot...
> 
> > +s->code_gen_epilogue = s->code_ptr;
> > +tcg_out_mov(s, TCG_TYPE_REG, TCG_REG_V0, TCG_REG_ZERO);
> 
> ... instead of here?

There is no particular reason in the current usage of goto_ptr. It's
just that in the future we might want to use code_gen_epilogue for
other reasons or use the tcg_out_opc_reg to do other things. It's
probably better to have a consistent behaviour across all TCG
targets.

That said if you prefer, I am find sending a v2 with the zeroing moved
to the delay slot.

-- 
Aurelien Jarno  GPG: 4096R/1DDD8C9B
aurel...@aurel32.net http://www.aurel32.net

Re: [Qemu-devel] [PATCH v5++ 1/3] tcg/mips: implement goto_ptr

[Richard Henderson]

On 04/30/2017 04:52 PM, Aurelien Jarno wrote:

+/* jmp to the given host address (could be epilogue) */
+tcg_out_opc_reg(s, OPC_JR, 0, a0, 0);
+tcg_out_nop(s);


Any particular reason not to do the zeroing in the delay slot...


+s->code_gen_epilogue = s->code_ptr;
+tcg_out_mov(s, TCG_TYPE_REG, TCG_REG_V0, TCG_REG_ZERO);


... instead of here?


r~

Re: [Qemu-devel] [PATCH v5++ 1/3] tcg/mips: implement goto_ptr

[Philippe Mathieu-Daudé]

On 04/30/2017 11:52 AM, Aurelien Jarno wrote:

Signed-off-by: Aurelien Jarno 


Reviewed-by: Philippe Mathieu-Daudé 


---
 tcg/mips/tcg-target.h |  2 +-
 tcg/mips/tcg-target.inc.c | 13 +
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/tcg/mips/tcg-target.h b/tcg/mips/tcg-target.h
index e3240cfba7..d75cb63ed3 100644
--- a/tcg/mips/tcg-target.h
+++ b/tcg/mips/tcg-target.h
@@ -130,7 +130,7 @@ extern bool use_mips32r2_instructions;
 #define TCG_TARGET_HAS_muluh_i321
 #define TCG_TARGET_HAS_mulsh_i321
 #define TCG_TARGET_HAS_bswap32_i32  1
-#define TCG_TARGET_HAS_goto_ptr 0
+#define TCG_TARGET_HAS_goto_ptr 1

 #if TCG_TARGET_REG_BITS == 64
 #define TCG_TARGET_HAS_add2_i32 0
diff --git a/tcg/mips/tcg-target.inc.c b/tcg/mips/tcg-target.inc.c
index 01ac7b2c81..9e5b9f42da 100644
--- a/tcg/mips/tcg-target.inc.c
+++ b/tcg/mips/tcg-target.inc.c
@@ -1747,6 +1747,11 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode 
opc,
 tcg_out_nop(s);
 s->tb_jmp_reset_offset[a0] = tcg_current_code_size(s);
 break;
+case INDEX_op_goto_ptr:
+/* jmp to the given host address (could be epilogue) */
+tcg_out_opc_reg(s, OPC_JR, 0, a0, 0);
+tcg_out_nop(s);
+break;
 case INDEX_op_br:
 tcg_out_brcond(s, TCG_COND_EQ, TCG_REG_ZERO, TCG_REG_ZERO,
arg_label(a0));
@@ -2160,6 +2165,7 @@ static const TCGTargetOpDef mips_op_defs[] = {
 { INDEX_op_exit_tb, { } },
 { INDEX_op_goto_tb, { } },
 { INDEX_op_br, { } },
+{ INDEX_op_goto_ptr, { "r" } },

 { INDEX_op_ld8u_i32, { "r", "r" } },
 { INDEX_op_ld8s_i32, { "r", "r" } },
@@ -2451,6 +2457,13 @@ static void tcg_target_qemu_prologue(TCGContext *s)
 /* delay slot */
 tcg_out_mov(s, TCG_TYPE_PTR, TCG_AREG0, tcg_target_call_iarg_regs[0]);

+/*
+ * Return path for goto_ptr. Set return value to 0, a-la exit_tb,
+ * and fall through to the rest of the epilogue.
+ */
+s->code_gen_epilogue = s->code_ptr;
+tcg_out_mov(s, TCG_TYPE_REG, TCG_REG_V0, TCG_REG_ZERO);
+
 /* TB epilogue */
 tb_ret_addr = s->code_ptr;
 for (i = 0; i < ARRAY_SIZE(tcg_target_callee_save_regs); i++) {

[Qemu-devel] [PATCH v5++ 1/3] tcg/mips: implement goto_ptr

[Aurelien Jarno]

Signed-off-by: Aurelien Jarno 
---
 tcg/mips/tcg-target.h |  2 +-
 tcg/mips/tcg-target.inc.c | 13 +
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/tcg/mips/tcg-target.h b/tcg/mips/tcg-target.h
index e3240cfba7..d75cb63ed3 100644
--- a/tcg/mips/tcg-target.h
+++ b/tcg/mips/tcg-target.h
@@ -130,7 +130,7 @@ extern bool use_mips32r2_instructions;
 #define TCG_TARGET_HAS_muluh_i321
 #define TCG_TARGET_HAS_mulsh_i321
 #define TCG_TARGET_HAS_bswap32_i32  1
-#define TCG_TARGET_HAS_goto_ptr 0
+#define TCG_TARGET_HAS_goto_ptr 1
 
 #if TCG_TARGET_REG_BITS == 64
 #define TCG_TARGET_HAS_add2_i32 0
diff --git a/tcg/mips/tcg-target.inc.c b/tcg/mips/tcg-target.inc.c
index 01ac7b2c81..9e5b9f42da 100644
--- a/tcg/mips/tcg-target.inc.c
+++ b/tcg/mips/tcg-target.inc.c
@@ -1747,6 +1747,11 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode 
opc,
 tcg_out_nop(s);
 s->tb_jmp_reset_offset[a0] = tcg_current_code_size(s);
 break;
+case INDEX_op_goto_ptr:
+/* jmp to the given host address (could be epilogue) */
+tcg_out_opc_reg(s, OPC_JR, 0, a0, 0);
+tcg_out_nop(s);
+break;
 case INDEX_op_br:
 tcg_out_brcond(s, TCG_COND_EQ, TCG_REG_ZERO, TCG_REG_ZERO,
arg_label(a0));
@@ -2160,6 +2165,7 @@ static const TCGTargetOpDef mips_op_defs[] = {
 { INDEX_op_exit_tb, { } },
 { INDEX_op_goto_tb, { } },
 { INDEX_op_br, { } },
+{ INDEX_op_goto_ptr, { "r" } },
 
 { INDEX_op_ld8u_i32, { "r", "r" } },
 { INDEX_op_ld8s_i32, { "r", "r" } },
@@ -2451,6 +2457,13 @@ static void tcg_target_qemu_prologue(TCGContext *s)
 /* delay slot */
 tcg_out_mov(s, TCG_TYPE_PTR, TCG_AREG0, tcg_target_call_iarg_regs[0]);
 
+/*
+ * Return path for goto_ptr. Set return value to 0, a-la exit_tb,
+ * and fall through to the rest of the epilogue.
+ */
+s->code_gen_epilogue = s->code_ptr;
+tcg_out_mov(s, TCG_TYPE_REG, TCG_REG_V0, TCG_REG_ZERO);
+
 /* TB epilogue */
 tb_ret_addr = s->code_ptr;
 for (i = 0; i < ARRAY_SIZE(tcg_target_callee_save_regs); i++) {
-- 
2.11.0