Check that the value matches opcode_wregs

Signed-off-by: Taylor Simpson <ltaylorsimpson@gmail.com>
---
 target/hexagon/insn.h             | 1 +
 target/hexagon/decode.c           | 3 +++
 target/hexagon/gen_trans_funcs.py | 4 ++++
 3 files changed, 8 insertions(+)

diff --git a/target/hexagon/insn.h b/target/hexagon/insn.h
index a770379958..24dcf7fe9f 100644
--- a/target/hexagon/insn.h
+++ b/target/hexagon/insn.h
@@ -41,6 +41,7 @@ struct Instruction {
     uint32_t new_value_producer_slot:4;
     int32_t new_read_idx;
     int32_t dest_idx;
+    bool has_pred_dest;
 
     bool part1;              /*
                               * cmp-jumps are split into two insns.
diff --git a/target/hexagon/decode.c b/target/hexagon/decode.c
index a4d8500fea..84a3899556 100644
--- a/target/hexagon/decode.c
+++ b/target/hexagon/decode.c
@@ -366,6 +366,9 @@ static void decode_shuffle_for_execution(Packet *packet)
         for (flag = false, i = 0; i < last_insn + 1; i++) {
             int opcode = packet->insn[i].opcode;
 
+            g_assert(packet->insn[i].has_pred_dest ==
+                     (strstr(opcode_wregs[opcode], "Pd4") ||
+                      strstr(opcode_wregs[opcode], "Pe4")));
             if ((strstr(opcode_wregs[opcode], "Pd4") ||
                  strstr(opcode_wregs[opcode], "Pe4")) &&
                 GET_ATTRIB(opcode, A_STORE) == 0) {
diff --git a/target/hexagon/gen_trans_funcs.py b/target/hexagon/gen_trans_funcs.py
index 07292e0170..f1972fd2dd 100755
--- a/target/hexagon/gen_trans_funcs.py
+++ b/target/hexagon/gen_trans_funcs.py
@@ -86,6 +86,7 @@ def gen_trans_funcs(f):
 
         new_read_idx = -1
         dest_idx = -1
+        has_pred_dest = "false"
         for regno, regstruct in enumerate(regs):
             reg_type, reg_id, _, _ = regstruct
             reg = hex_common.get_register(tag, reg_type, reg_id)
@@ -96,6 +97,8 @@ def gen_trans_funcs(f):
                 new_read_idx = regno
             if reg.is_written() and dest_idx == -1:
                 dest_idx = regno
+            if reg_type == "P" and not reg.is_read():
+                has_pred_dest = "true"
 
         if len(imms) != 0:
             mark_which_imm_extended(f, tag)
@@ -119,6 +122,7 @@ def gen_trans_funcs(f):
         f.write(code_fmt(f"""\
             insn->new_read_idx = {new_read_idx};
             insn->dest_idx = {dest_idx};
+            insn->has_pred_dest = {has_pred_dest};
         """))
         f.write(textwrap.dedent(f"""\
                 return true;
-- 
2.34.1

On Mon, 26 Feb 2024 13:17:17 -0700 Taylor Simpson <ltaylorsimpson@gmail.com> wrote:
>
> diff --git a/target/hexagon/gen_trans_funcs.py b/target/hexagon/gen_trans_funcs.py
> index 07292e0170..f1972fd2dd 100755
> --- a/target/hexagon/gen_trans_funcs.py
> +++ b/target/hexagon/gen_trans_funcs.py
> @@ -86,6 +86,7 @@ def gen_trans_funcs(f):
>  
>          new_read_idx = -1
>          dest_idx = -1
> +        has_pred_dest = "false"
>          for regno, regstruct in enumerate(regs):
>              reg_type, reg_id, _, _ = regstruct
>              reg = hex_common.get_register(tag, reg_type, reg_id)
> @@ -96,6 +97,8 @@ def gen_trans_funcs(f):
>                  new_read_idx = regno
>              if reg.is_written() and dest_idx == -1:
>                  dest_idx = regno
> +            if reg_type == "P" and not reg.is_read():
> +                has_pred_dest = "true"

I got a bit confused here. Why do we use "not reg.is_read()"? I though this
would be "reg.is_written()".

> -----Original Message-----
> From: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
> Sent: Tuesday, February 27, 2024 8:21 AM
> To: Taylor Simpson <ltaylorsimpson@gmail.com>
> Cc: qemu-devel@nongnu.org; bcain@quicinc.com;
> quic_mathbern@quicinc.com; sidneym@quicinc.com;
> quic_mliebel@quicinc.com; richard.henderson@linaro.org;
> philmd@linaro.org; ale@rev.ng; anjo@rev.ng
> Subject: Re: [PATCH 4/9] Hexagon (target/hexagon) Mark has_pred_dest in
> trans functions
> 
> On Mon, 26 Feb 2024 13:17:17 -0700 Taylor Simpson
> <ltaylorsimpson@gmail.com> wrote:
> >
> > diff --git a/target/hexagon/gen_trans_funcs.py
> > b/target/hexagon/gen_trans_funcs.py
> > index 07292e0170..f1972fd2dd 100755
> > --- a/target/hexagon/gen_trans_funcs.py
> > +++ b/target/hexagon/gen_trans_funcs.py
> > @@ -86,6 +86,7 @@ def gen_trans_funcs(f):
> >
> >          new_read_idx = -1
> >          dest_idx = -1
> > +        has_pred_dest = "false"
> >          for regno, regstruct in enumerate(regs):
> >              reg_type, reg_id, _, _ = regstruct
> >              reg = hex_common.get_register(tag, reg_type, reg_id) @@
> > -96,6 +97,8 @@ def gen_trans_funcs(f):
> >                  new_read_idx = regno
> >              if reg.is_written() and dest_idx == -1:
> >                  dest_idx = regno
> > +            if reg_type == "P" and not reg.is_read():
> > +                has_pred_dest = "true"
> 
> I got a bit confused here. Why do we use "not reg.is_read()"? I though
this
> would be "reg.is_written()".

The original C code is
            if ((strstr(opcode_wregs[opcode], "Pd4") ||
                 strstr(opcode_wregs[opcode], "Pe4")) &&
Checking for reg.is_written() would also match Px4, which is read-write.

Would it be more clear if we checked for reg.is_written() and non
reg.is_read()?

Thanks,
Taylor