From ccdb08ef4ed8f96e79aa06cf5e806c9c487d58ad Mon Sep 17 00:00:00 2001
From: Paul Eggert <address@hidden>
Date: Sat, 25 Aug 2018 13:39:18 -0700
Subject: [PATCH] Improve performance of CONSP, FIXNUMP, etc.
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Optimization opportunity noted by Pip Cet in:
https://lists.gnu.org/r/emacs-devel/2018-08/msg00828.html
On my platform (Fedora 28 x86-64, AMD Phenom II X4 910e,
user+system time), this improved ‘make compile-always’
performance by 0.4% and shrank text size by a similar amount.
* src/lisp.h (TAGGEDP, lisp_h_TAGGEDP): New macros and function.
(lisp_h_CONSP, lisp_h_FLOATP, lisp_h_SYMBOLP)
(lisp_h_VECTORLIKEP, make_lisp_ptr, STRINGP): Use them.
(lisp_h_FIXNUMP): Use the same idea that lisp_h_TAGGEDP uses.
---
 src/lisp.h | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/src/lisp.h b/src/lisp.h
index bca4dfbb60..fb11a11fda 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -362,10 +362,13 @@ typedef EMACS_INT Lisp_Word;
 #define lisp_h_CHECK_SYMBOL(x) CHECK_TYPE (SYMBOLP (x), Qsymbolp, x)
 #define lisp_h_CHECK_TYPE(ok, predicate, x) \
    ((ok) ? (void) 0 : wrong_type_argument (predicate, x))
-#define lisp_h_CONSP(x) (XTYPE (x) == Lisp_Cons)
+#define lisp_h_CONSP(x) TAGGEDP (x, Lisp_Cons)
 #define lisp_h_EQ(x, y) (XLI (x) == XLI (y))
-#define lisp_h_FLOATP(x) (XTYPE (x) == Lisp_Float)
-#define lisp_h_FIXNUMP(x) ((XTYPE (x) & (Lisp_Int0 | ~Lisp_Int1)) == Lisp_Int0)
+#define lisp_h_FIXNUMP(x) \
+   (! (((unsigned) (XLI (x) >> (USE_LSB_TAG ? 0 : FIXNUM_BITS)) \
+	- (unsigned) (Lisp_Int0 >> !USE_LSB_TAG)) \
+       & ((1 << INTTYPEBITS) - 1)))
+#define lisp_h_FLOATP(x) TAGGEDP (x, Lisp_Float)
 #define lisp_h_NILP(x) EQ (x, Qnil)
 #define lisp_h_SET_SYMBOL_VAL(sym, v) \
    (eassert ((sym)->u.s.redirect == SYMBOL_PLAINVAL), \
@@ -375,8 +378,12 @@ typedef EMACS_INT Lisp_Word;
 #define lisp_h_SYMBOL_TRAPPED_WRITE_P(sym) (XSYMBOL (sym)->u.s.trapped_write)
 #define lisp_h_SYMBOL_VAL(sym) \
    (eassert ((sym)->u.s.redirect == SYMBOL_PLAINVAL), (sym)->u.s.val.value)
-#define lisp_h_SYMBOLP(x) (XTYPE (x) == Lisp_Symbol)
-#define lisp_h_VECTORLIKEP(x) (XTYPE (x) == Lisp_Vectorlike)
+#define lisp_h_SYMBOLP(x) TAGGEDP (x, Lisp_Symbol)
+#define lisp_h_TAGGEDP(a, tag) \
+   (! (((unsigned) (XLI (a) >> (USE_LSB_TAG ? 0 : VALBITS)) \
+	- (unsigned) (tag)) \
+       & ((1 << GCTYPEBITS) - 1)))
+#define lisp_h_VECTORLIKEP(x) TAGGEDP (x, Lisp_Vectorlike)
 #define lisp_h_XCAR(c) XCONS (c)->u.s.car
 #define lisp_h_XCDR(c) XCONS (c)->u.s.u.cdr
 #define lisp_h_XCONS(a) \
@@ -435,6 +442,7 @@ typedef EMACS_INT Lisp_Word;
 # define SYMBOL_TRAPPED_WRITE_P(sym) lisp_h_SYMBOL_TRAPPED_WRITE_P (sym)
 # define SYMBOL_VAL(sym) lisp_h_SYMBOL_VAL (sym)
 # define SYMBOLP(x) lisp_h_SYMBOLP (x)
+# define TAGGEDP(a, tag) lisp_h_TAGGEDP (a, tag)
 # define VECTORLIKEP(x) lisp_h_VECTORLIKEP (x)
 # define XCAR(c) lisp_h_XCAR (c)
 # define XCDR(c) lisp_h_XCDR (c)
@@ -647,6 +655,15 @@ INLINE enum Lisp_Type
 #endif
 }
 
+/* True if A has type tag TAG.
+   Equivalent to XTYPE (a) == TAG, but often faster.  */
+
+INLINE bool
+(TAGGEDP) (Lisp_Object a, enum Lisp_Type tag)
+{
+  return lisp_h_TAGGEDP (a, tag);
+}
+
 INLINE void
 (CHECK_TYPE) (int ok, Lisp_Object predicate, Lisp_Object x)
 {
@@ -1131,7 +1148,7 @@ INLINE Lisp_Object
 make_lisp_ptr (void *ptr, enum Lisp_Type type)
 {
   Lisp_Object a = TAG_PTR (type, ptr);
-  eassert (XTYPE (a) == type && XUNTAG (a, type, char) == ptr);
+  eassert (TAGGEDP (a, type) && XUNTAG (a, type, char) == ptr);
   return a;
 }
 
@@ -1364,7 +1381,7 @@ verify (alignof (struct Lisp_String) % GCALIGNMENT == 0);
 INLINE bool
 STRINGP (Lisp_Object x)
 {
-  return XTYPE (x) == Lisp_String;
+  return TAGGEDP (x, Lisp_String);
 }
 
 INLINE void
-- 
2.17.1