From 5b62317b697c04b4120a026e53309e04e15bd9e0 Mon Sep 17 00:00:00 2001
From: Nickolas Lloyd <ultrageek.lloyd@gmail.com>
Date: Sun, 29 Jan 2017 13:22:06 -0500
Subject: [PATCH] Small speed improvement for JITed lisp function dispatch

* src/alloc.c (make-byte-code):
* src/bytecode-jit.c (jit_byte_code__):
* src/bytecode.c [HAVE_LIBJIT] (exec_byte_code):
* src/eval.c (funcall_lambda):
* src/lisp.h (funcall_lambda): Store pointer to bytecode execution function
(either `exec_byte_code' or `jit_exec') in Lisp_Compiled objects to avoid
the need for an extra function call in `exec_byte_code'.
---
 src/alloc.c        |  1 +
 src/bytecode-jit.c |  1 +
 src/bytecode.c     |  4 +---
 src/eval.c         | 12 +++++++++---
 src/lisp.h         |  5 +++--
 5 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/alloc.c b/src/alloc.c
index 1a3f747ec5c..fe7bc12f414 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3510,6 +3510,7 @@ usage: (make-byte-code ARGLIST BYTE-CODE CONSTANTS DEPTH &optional DOCSTRING INT
 
   /* set rest size so that total footprint = COMPILED_JIT_CLOSURE + 1 */
   XSETPVECTYPESIZE (p, PVEC_COMPILED, size, COMPILED_JIT_CLOSURE + 1 - size);
+  p->contents[COMPILED_INTERPRETER] = (Lisp_Object )exec_byte_code;
   p->contents[COMPILED_JIT_CTXT] = (Lisp_Object )NULL;
   p->contents[COMPILED_JIT_CLOSURE] = (Lisp_Object )NULL;
   XSETCOMPILED (val, p);
diff --git a/src/bytecode-jit.c b/src/bytecode-jit.c
index 0d058c95b07..974b6aabac2 100644
--- a/src/bytecode-jit.c
+++ b/src/bytecode-jit.c
@@ -1588,6 +1588,7 @@ jit_byte_code__ (Lisp_Object byte_code)
     jit_context_build_end (ctxt.libjit_ctxt);
     if (err)
       emacs_abort ();
+    ASET (byte_code, COMPILED_INTERPRETER, (Lisp_Object )jit_exec);
     ASET (byte_code, COMPILED_JIT_CTXT, (Lisp_Object )ctxt.libjit_ctxt);
     ASET (byte_code, COMPILED_JIT_CLOSURE,
 	  (Lisp_Object )jit_function_to_closure (ctxt.func));
diff --git a/src/bytecode.c b/src/bytecode.c
index 8b132caac0a..3e64d2f42b6 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -1291,9 +1291,7 @@ exec_byte_code (Lisp_Object byte_code, Lisp_Object args_template,
 		ptrdiff_t nargs, Lisp_Object *args)
 {
 #ifdef HAVE_LIBJIT
-  if (AREF (byte_code, COMPILED_JIT_CTXT) != (Lisp_Object )NULL)
-    return jit_exec (byte_code, args_template, nargs, args);
-  else if (byte_code_jit_on)
+  if (byte_code_jit_on)
     {
       jit_byte_code__ (byte_code);
       return jit_exec (byte_code, args_template, nargs, args);
diff --git a/src/eval.c b/src/eval.c
index f2e6ba85214..57af384f774 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2954,8 +2954,11 @@ funcall_lambda (Lisp_Object fun, ptrdiff_t nargs,
 	     and constants vector yet, fetch them from the file.  */
 	  if (CONSP (AREF (fun, COMPILED_BYTECODE)))
 	    Ffetch_bytecode (fun);
-	  return exec_byte_code (fun, syms_left,
-				 nargs, arg_vector);
+	  Lisp_Object (*interpreter)(Lisp_Object, Lisp_Object,
+				     ptrdiff_t, Lisp_Object *) =
+	    (void *)AREF (fun, COMPILED_INTERPRETER);
+	  return interpreter (fun, syms_left,
+			      nargs, arg_vector);
 	}
       lexenv = Qnil;
     }
@@ -3029,7 +3032,10 @@ funcall_lambda (Lisp_Object fun, ptrdiff_t nargs,
 	 and constants vector yet, fetch them from the file.  */
       if (CONSP (AREF (fun, COMPILED_BYTECODE)))
 	Ffetch_bytecode (fun);
-      val = exec_byte_code (fun, Qnil, 0, 0);
+      Lisp_Object (*interpreter)(Lisp_Object, Lisp_Object,
+				 ptrdiff_t, Lisp_Object *) =
+	(void *)AREF (fun, COMPILED_INTERPRETER);
+      val = interpreter (fun, Qnil, 0, 0);
     }
 
   return unbind_to (count, val);
diff --git a/src/lisp.h b/src/lisp.h
index 931dcef7712..79cd85b736b 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2592,8 +2592,9 @@ enum Lisp_Compiled
     COMPILED_STACK_DEPTH = 3,
     COMPILED_DOC_STRING = 4,
     COMPILED_INTERACTIVE = 5,
-    COMPILED_JIT_CTXT = 6,
-    COMPILED_JIT_CLOSURE = 7
+    COMPILED_INTERPRETER = 6,
+    COMPILED_JIT_CTXT = 7,
+    COMPILED_JIT_CLOSURE = 8
   };
 
 /* Flag bits in a character.  These also get used in termhooks.h.
-- 
2.39.5