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

[Taylor Simpson]

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.

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, 553 with env

Signed-off-by: Taylor Simpson <ltaylorsimpson@gmail.com>
---
 target/hexagon/gen_tcg.h         |  3 +++
 target/hexagon/attribs_def.h.inc |  1 +
 target/hexagon/hex_common.py     | 22 +++++++++++++++++-----
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/target/hexagon/gen_tcg.h b/target/hexagon/gen_tcg.h
index 1c4391b415..e9ac2e3fe0 100644
--- a/target/hexagon/gen_tcg.h
+++ b/target/hexagon/gen_tcg.h
@@ -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/attribs_def.h.inc b/target/hexagon/attribs_def.h.inc
index 87942d46f4..8949ee09cf 100644
--- a/target/hexagon/attribs_def.h.inc
+++ b/target/hexagon/attribs_def.h.inc
@@ -117,6 +117,7 @@ DEF_ATTRIB(IMPLICIT_READS_P1, "Reads the P1 register", "", 
"")
 DEF_ATTRIB(IMPLICIT_READS_P2, "Reads the P2 register", "", "")
 DEF_ATTRIB(IMPLICIT_READS_P3, "Reads the P3 register", "", "")
 DEF_ATTRIB(IMPLICIT_WRITES_USR, "May write USR", "", "")
+DEF_ATTRIB(IMPLICIT_READS_SP, "Reads the SP register", "", "")
 DEF_ATTRIB(COMMUTES, "The operation is communitive", "", "")
 DEF_ATTRIB(DEALLOCRET, "dealloc_return", "", "")
 DEF_ATTRIB(DEALLOCFRAME, "deallocframe", "", "")
diff --git a/target/hexagon/hex_common.py b/target/hexagon/hex_common.py
index 195620c7ec..12bc410bb2 100755
--- a/target/hexagon/hex_common.py
+++ b/target/hexagon/hex_common.py
@@ -101,6 +101,7 @@ def calculate_attribs():
     add_qemu_macro_attrib('fLSBNEW1', 'A_IMPLICIT_READS_P1')
     add_qemu_macro_attrib('fLSBNEW1NOT', 'A_IMPLICIT_READS_P1')
     add_qemu_macro_attrib('fREAD_P3', 'A_IMPLICIT_READS_P3')
+    add_qemu_macro_attrib('fREAD_SP', 'A_IMPLICIT_READS_SP')
 
     # Recurse down macros, find attributes from sub-macros
     macroValues = list(macros.values())
@@ -197,6 +198,16 @@ def get_tagimms():
     return dict(zip(tags, list(map(compute_tag_immediates, tags))))
 
 
+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] or
+            "A_IMPLICIT_READS_P0" in attribdict[tag] or
+            "A_IMPLICIT_READS_SP" in attribdict[tag])
+
+
 def need_slot(tag):
     if (
         "A_CVI_SCATTER" not in attribdict[tag]
@@ -1060,11 +1071,12 @@ 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):
-- 
2.34.1