From 76753e7fcd0153c82794b436092c87140c38c16d Mon Sep 17 00:00:00 2001
From: Nicholas Clark <nick@ccl4.org>
Date: Mon, 4 Feb 2008 13:59:21 +0000
Subject: [PATCH] Micro-optimise the order of the context types. [Because I can
 :-)] Here saves 72 bytes in pp_ctl.o. Small, but in the right direction.

p4raw-id: //depot/perl@33232
---
 cop.h    | 31 +++++++++++++++++++------------
 perl.h   |  8 ++++----
 pp_ctl.c | 13 ++++++++-----
 3 files changed, 31 insertions(+), 21 deletions(-)

diff --git a/cop.h b/cop.h
index 8cfc88d..272dbcc 100644
--- a/cop.h
+++ b/cop.h
@@ -650,20 +650,27 @@ struct context {
 };
 #define cx_type cx_u.cx_subst.sbu_type
 
+/* If you re-order these, there is also an array of uppercase names in perl.h
+   and a static array of context names in pp_ctl.c  */
 #define CXTYPEMASK	0xf
 #define CXt_NULL	0
-#define CXt_SUB		1
-#define CXt_EVAL	2
-#define CXt_WHEN	3
-#define CXt_SUBST	4
-#define CXt_BLOCK	5
-#define CXt_FORMAT	6
-#define CXt_GIVEN	7
+#define CXt_WHEN	1
+#define CXt_BLOCK	2
+/* When micro-optimising :-) keep GIVEN next to the LOOPs, as these 5 share a
+   jump table in pp_ctl.c
+   The first 4 don't have a 'case' in at least one switch statement in pp_ctl.c
+*/
+#define CXt_GIVEN	3
 /* This is first so that CXt_LOOP_FOR|CXt_LOOP_LAZYIV is CXt_LOOP_LAZYIV */
-#define CXt_LOOP_FOR	8
-#define CXt_LOOP_PLAIN	9
-#define CXt_LOOP_LAZYSV	10
-#define CXt_LOOP_LAZYIV	11
+#define CXt_LOOP_FOR	4
+#define CXt_LOOP_PLAIN	5
+#define CXt_LOOP_LAZYSV	6
+#define CXt_LOOP_LAZYIV	7
+#define CXt_SUB		8
+#define CXt_FORMAT      9
+#define CXt_EVAL       10
+#define CXt_SUBST      11
+/* SUBST doesn't feature in all switch statements.  */
 
 /* private flags for CXt_SUB and CXt_NULL
    However, this is checked in many places which do not check the type, so
@@ -689,7 +696,7 @@ struct context {
 #define CXp_ONCE	0x10	/* What was sbu_once in struct subst */
 
 #define CxTYPE(c)	((c)->cx_type & CXTYPEMASK)
-#define CxTYPE_is_LOOP(c)	(((c)->cx_type & 0xC) == 0x8)
+#define CxTYPE_is_LOOP(c)	(((c)->cx_type & 0xC) == 0x4)
 #define CxMULTICALL(c)	(((c)->cx_type & CXp_MULTICALL)			\
 			 == CXp_MULTICALL)
 #define CxREALEVAL(c)	(((c)->cx_type & (CXTYPEMASK|CXp_REAL))		\
diff --git a/perl.h b/perl.h
index ba95492..35bc28a 100644
--- a/perl.h
+++ b/perl.h
@@ -4363,17 +4363,17 @@ EXTCONST unsigned char PL_freq[];
 #ifdef DOINIT
 EXTCONST char* const PL_block_type[] = {
 	"NULL",
-	"SUB",
-	"EVAL",
 	"WHEN",
-	"SUBST",
 	"BLOCK",
-	"FORMAT",
 	"GIVEN",
 	"LOOP_FOR",
 	"LOOP_PLAIN",
 	"LOOP_LAZYSV",
 	"LOOP_LAZYIV",
+	"SUB",
+	"FORMAT",
+	"EVAL",
+	"SUBST"
 };
 #else
 EXTCONST char* PL_block_type[];
diff --git a/pp_ctl.c b/pp_ctl.c
index b0ffcb5..f6b788f 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -1224,14 +1224,17 @@ PP(pp_flop)
 
 static const char * const context_name[] = {
     "pseudo-block",
+    "when",
+    NULL, /* CXt_BLOCK never actually needs "block" */
+    "given",
+    NULL, /* CXt_LOOP_FOR never actually needs "loop" */
+    NULL, /* CXt_LOOP_PLAIN never actually needs "loop" */
+    NULL, /* CXt_LOOP_LAZYSV never actually needs "loop" */
+    NULL, /* CXt_LOOP_LAZYIV never actually needs "loop" */
     "subroutine",
+    "format",
     "eval",
-    "loop",
     "substitution",
-    "block",
-    "format",
-    "given",
-    "when"
 };
 
 STATIC I32
-- 
2.7.4