Hexagon (target/hexagon) Only pass env to generated helper when needed

Currently, we pass env to every generated helper.  When the semantics of
the instruction only depend on the arguments, this is unnecessary and
adds extra overhead to the helper call.

We add the TCG_CALL_NO_RWG_SE flag to any non-HVX helpers that don't get
the ptr to env.

The A2_nop and SA1_setin1 instructions end up with no arguments.  This
results in a "old-style function definition" error from the compiler, so
we write overrides for them.

With this change, the number of helpers with env argument is
    idef-parser enabled:    329 total, 23 with env
    idef-parser disabled:   1543 total, 550 with env

Signed-off-by: Taylor Simpson <ltaylorsimpson@gmail.com>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Tested-by: Anton Johansson <anjo@rev.ng>
Message-Id: <20240214042726.19290-4-ltaylorsimpson@gmail.com>
Signed-off-by: Brian Cain <bcain@quicinc.com>

diff --git a/target/hexagon/gen_helper_protos.py b/target/hexagon/gen_helper_protos.py
index c82b0f54e4d8e10e85cfba6c8fa6979c0ecf54da..f8578d5033031a243b8549090d3616a0604eb733 100755 (executable)
--- a/target/hexagon/gen_helper_protos.py
+++ b/target/hexagon/gen_helper_protos.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 
 ##
-##  Copyright(c) 2019-2023 Qualcomm Innovation Center, Inc. All Rights Reserved.
+##  Copyright(c) 2019-2024 Qualcomm Innovation Center, Inc. All Rights Reserved.
 ##
 ##  This program is free software; you can redistribute it and/or modify
 ##  it under the terms of the GNU General Public License as published by
@@ -40,7 +40,15 @@ def gen_helper_prototype(f, tag, tagregs, tagimms):
         declared.append(arg.proto_arg)
 
     arguments = ", ".join(declared)
-    f.write(f"DEF_HELPER_{len(declared) - 1}({tag}, {arguments})\n")
+
+    ## Add the TCG_CALL_NO_RWG_SE flag to helpers that don't take the env
+    ## argument and aren't HVX instructions.  Since HVX instructions take
+    ## pointers to their arguments, they will have side effects.
+    if hex_common.need_env(tag) or hex_common.is_hvx_insn(tag):
+        f.write(f"DEF_HELPER_{len(declared) - 1}({tag}, {arguments})\n")
+    else:
+        f.write(f"DEF_HELPER_FLAGS_{len(declared) - 1}({tag}, "
+                f"TCG_CALL_NO_RWG_SE, {arguments})\n")
 
 
 def main():

diff --git a/target/hexagon/gen_tcg.h b/target/hexagon/gen_tcg.h
index 1c4391b4156ff304b76fa7995a8bc66dcab0d122..3fc1f4e28127d0c973240650a3d6a0ee2e77500b 100644 (file)
--- a/target/hexagon/gen_tcg.h
+++ b/target/hexagon/gen_tcg.h
@@ -1,5 +1,5 @@
 /*
- *  Copyright(c) 2019-2023 Qualcomm Innovation Center, Inc. All Rights Reserved.
+ *  Copyright(c) 2019-2024 Qualcomm Innovation Center, Inc. All Rights Reserved.
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -1369,3 +1369,6 @@
         gen_helper_raise_exception(tcg_env, excp); \
     } while (0)
 #endif
+
+#define fGEN_TCG_A2_nop(SHORTCODE) do { } while (0)
+#define fGEN_TCG_SA1_setin1(SHORTCODE) tcg_gen_movi_tl(RdV, -1)

diff --git a/target/hexagon/hex_common.py b/target/hexagon/hex_common.py
index 03c9ce1d8a03b30fe8e424ac6f7cf49084cc5649..c09b48bb36e1b4ca7191777f3d5f2d9555a07843 100755 (executable)
--- a/target/hexagon/hex_common.py
+++ b/target/hexagon/hex_common.py
@@ -206,6 +206,18 @@ def need_sp(tag):
     return "A_IMPLICIT_READS_SP" in attribdict[tag]
 
 
+def is_hvx_insn(tag):
+    return "A_CVI" in attribdict[tag]
+
+
+def need_env(tag):
+    return ("A_STORE" in attribdict[tag] or
+            "A_LOAD" in attribdict[tag] or
+            "A_CVI_GATHER" in attribdict[tag] or
+            "A_CVI_SCATTER" in attribdict[tag] or
+            "A_IMPLICIT_WRITES_USR" in attribdict[tag])
+
+
 def need_slot(tag):
     if (
         "A_CVI_SCATTER" not in attribdict[tag]
@@ -1085,11 +1097,12 @@ def helper_args(tag, regs, imms):
     args = []
 
     ## First argument is the CPU state
-    args.append(HelperArg(
-        "env",
-        "tcg_env",
-        "CPUHexagonState *env"
-    ))
+    if need_env(tag):
+        args.append(HelperArg(
+            "env",
+            "tcg_env",
+            "CPUHexagonState *env"
+        ))
 
     ## For predicated instructions, we pass in the destination register
     if is_predicated(tag):