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[src/trunk]: src/usr.bin/make make: migrate ModifyWord functions to use Subst...



details:   https://anonhg.NetBSD.org/src/rev/4b8c156b0340
branches:  trunk
changeset: 961167:4b8c156b0340
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Apr 11 18:44:57 2021 +0000

description:
make: migrate ModifyWord functions to use Substring

This benefits the modifiers ':T' and ':H' since these scan the word from
the end.  The SysV modifier '.c=.o' does not benefit yet, this will be
done in a follow-up commit.

Currently ModifyWords calls strlen for each single word, which degrades
performance.  This will be cleaned up in a follow-up commit as well.

No functional change.

diffstat:

 usr.bin/make/str.h |   41 ++++++++++++++-
 usr.bin/make/var.c |  142 ++++++++++++++++++++++++++++++----------------------
 2 files changed, 123 insertions(+), 60 deletions(-)

diffs (truncated from 419 to 300 lines):

diff -r 2c00160ac046 -r 4b8c156b0340 usr.bin/make/str.h
--- a/usr.bin/make/str.h        Sun Apr 11 18:18:39 2021 +0000
+++ b/usr.bin/make/str.h        Sun Apr 11 18:44:57 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: str.h,v 1.1 2021/04/11 12:06:53 rillig Exp $   */
+/*     $NetBSD: str.h,v 1.2 2021/04/11 18:44:57 rillig Exp $   */
 
 /*
  Copyright (c) 2021 Roland Illig <rillig%NetBSD.org@localhost>
@@ -162,6 +162,12 @@
 }
 
 MAKE_INLINE bool
+Substring_IsEmpty(Substring sub)
+{
+       return sub.start == sub.end;
+}
+
+MAKE_INLINE bool
 Substring_Equals(Substring sub, const char *str)
 {
        size_t len = strlen(str);
@@ -183,6 +189,39 @@
        return FStr_InitOwn(bmake_strsedup(sub.start, sub.end));
 }
 
+MAKE_INLINE const char *
+Substring_LastIndex(Substring sub, char ch)
+{
+       const char *p;
+
+       for (p = sub.end; p != sub.start; p--)
+               if (p[-1] == ch)
+                       return p - 1;
+       return NULL;
+}
+
+MAKE_INLINE Substring
+Substring_Dirname(Substring pathname)
+{
+       const char *p;
+
+       for (p = pathname.end; p != pathname.start; p--)
+               if (p[-1] == '/')
+                       return Substring_Init(pathname.start, p - 1);
+       return Substring_InitStr(".");
+}
+
+MAKE_INLINE Substring
+Substring_Basename(Substring pathname)
+{
+       const char *p;
+
+       for (p = pathname.end; p != pathname.start; p--)
+               if (p[-1] == '/')
+                       return Substring_Init(p, pathname.end);
+       return pathname;
+}
+
 
 MAKE_INLINE void
 LazyBuf_Init(LazyBuf *buf, Substring expected)
diff -r 2c00160ac046 -r 4b8c156b0340 usr.bin/make/var.c
--- a/usr.bin/make/var.c        Sun Apr 11 18:18:39 2021 +0000
+++ b/usr.bin/make/var.c        Sun Apr 11 18:44:57 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: var.c,v 1.918 2021/04/11 17:48:01 rillig Exp $ */
+/*     $NetBSD: var.c,v 1.919 2021/04/11 18:44:57 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -140,7 +140,7 @@
 #include "metachar.h"
 
 /*     "@(#)var.c      8.3 (Berkeley) 3/19/94" */
-MAKE_RCSID("$NetBSD: var.c,v 1.918 2021/04/11 17:48:01 rillig Exp $");
+MAKE_RCSID("$NetBSD: var.c,v 1.919 2021/04/11 18:44:57 rillig Exp $");
 
 /*
  * Variables are defined using one of the VAR=value assignments.  Their
@@ -1334,6 +1334,12 @@
        SepBuf_AddBytes(buf, str, strlen(str));
 }
 
+static void
+SepBuf_AddSubstring(SepBuf *buf, Substring sub)
+{
+       SepBuf_AddBytesBetween(buf, sub.start, sub.end);
+}
+
 static char *
 SepBuf_DoneData(SepBuf *buf)
 {
@@ -1348,8 +1354,12 @@
  *
  * For example, when evaluating the modifier ':M*b' in ${:Ua b c:M*b}, the
  * callback is called 3 times, once for "a", "b" and "c".
+ *
+ * Some ModifyWord functions assume that they are always passed a
+ * null-terminated substring, which is currently guaranteed but may change in
+ * the future.
  */
-typedef void (*ModifyWordProc)(const char *word, SepBuf *buf, void *data);
+typedef void (*ModifyWordProc)(Substring word, SepBuf *buf, void *data);
 
 
 /*
@@ -1358,13 +1368,9 @@
  */
 /*ARGSUSED*/
 static void
-ModifyWord_Head(const char *word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
+ModifyWord_Head(Substring word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
 {
-       const char *slash = strrchr(word, '/');
-       if (slash != NULL)
-               SepBuf_AddBytesBetween(buf, word, slash);
-       else
-               SepBuf_AddStr(buf, ".");
+       SepBuf_AddSubstring(buf, Substring_Dirname(word));
 }
 
 /*
@@ -1373,9 +1379,9 @@
  */
 /*ARGSUSED*/
 static void
-ModifyWord_Tail(const char *word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
+ModifyWord_Tail(Substring word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
 {
-       SepBuf_AddStr(buf, str_basename(word));
+       SepBuf_AddSubstring(buf, Substring_Basename(word));
 }
 
 /*
@@ -1384,11 +1390,11 @@
  */
 /*ARGSUSED*/
 static void
-ModifyWord_Suffix(const char *word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
+ModifyWord_Suffix(Substring word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
 {
-       const char *lastDot = strrchr(word, '.');
+       const char *lastDot = Substring_LastIndex(word, '.');
        if (lastDot != NULL)
-               SepBuf_AddStr(buf, lastDot + 1);
+               SepBuf_AddBytesBetween(buf, lastDot + 1, word.end);
 }
 
 /*
@@ -1397,11 +1403,13 @@
  */
 /*ARGSUSED*/
 static void
-ModifyWord_Root(const char *word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
+ModifyWord_Root(Substring word, SepBuf *buf, void *dummy MAKE_ATTR_UNUSED)
 {
-       const char *lastDot = strrchr(word, '.');
-       size_t len = lastDot != NULL ? (size_t)(lastDot - word) : strlen(word);
-       SepBuf_AddBytes(buf, word, len);
+       const char *lastDot, *end;
+
+       lastDot = Substring_LastIndex(word, '.');
+       end = lastDot != NULL ? lastDot : word.end;
+       SepBuf_AddBytesBetween(buf, word.start, end);
 }
 
 /*
@@ -1409,12 +1417,13 @@
  * Place the word in the buffer if it matches the given pattern.
  */
 static void
-ModifyWord_Match(const char *word, SepBuf *buf, void *data)
+ModifyWord_Match(Substring word, SepBuf *buf, void *data)
 {
        const char *pattern = data;
 
-       if (Str_Match(word, pattern))
-               SepBuf_AddStr(buf, word);
+       assert(word.end[0] == '\0');    /* assume null-terminated word */
+       if (Str_Match(word.start, pattern))
+               SepBuf_AddSubstring(buf, word);
 }
 
 /*
@@ -1422,12 +1431,13 @@
  * Place the word in the buffer if it doesn't match the given pattern.
  */
 static void
-ModifyWord_NoMatch(const char *word, SepBuf *buf, void *data)
+ModifyWord_NoMatch(Substring word, SepBuf *buf, void *data)
 {
        const char *pattern = data;
 
-       if (!Str_Match(word, pattern))
-               SepBuf_AddStr(buf, word);
+       assert(word.end[0] == '\0');    /* assume null-terminated word */
+       if (!Str_Match(word.start, pattern))
+               SepBuf_AddSubstring(buf, word);
 }
 
 #ifdef SYSVVARSUB
@@ -1444,6 +1454,7 @@
  *     out_match_len returns the length of the match, if any.
  *     out_hasPercent returns whether the pattern contains a percent.
  */
+/* TODO: migrate to using Substring */
 static const char *
 SysVMatch(const char *word, const char *pattern,
          size_t *out_match_len, bool *out_hasPercent)
@@ -1498,18 +1509,20 @@
 
 /* Callback for ModifyWords to implement the :%.from=%.to modifier. */
 static void
-ModifyWord_SYSVSubst(const char *word, SepBuf *buf, void *data)
+ModifyWord_SYSVSubst(Substring word, SepBuf *buf, void *data)
 {
        const struct ModifyWord_SYSVSubstArgs *args = data;
        char *rhs_expanded;
        const char *rhs;
        const char *percent;
-
        size_t match_len;
        bool lhsPercent;
-       const char *match = SysVMatch(word, args->lhs, &match_len, &lhsPercent);
+       const char *match;
+
+       assert(word.end[0] == '\0');    /* assume null-terminated word */
+       match = SysVMatch(word.start, args->lhs, &match_len, &lhsPercent);
        if (match == NULL) {
-               SepBuf_AddStr(buf, word);
+               SepBuf_AddSubstring(buf, word);
                return;
        }
 
@@ -1565,29 +1578,29 @@
  * Perform a string substitution on the given word.
  */
 static void
-ModifyWord_Subst(const char *word, SepBuf *buf, void *data)
+ModifyWord_Subst(Substring word, SepBuf *buf, void *data)
 {
        struct ModifyWord_SubstArgs *args = data;
        size_t wordLen, lhsLen;
        const char *wordEnd, *match;
 
-       wordLen = strlen(word);
-       wordEnd = word + wordLen;
+       wordLen = Substring_Length(word);
+       wordEnd = word.end;
        if (args->pflags.subOnce && args->matched)
                goto nosub;
 
        lhsLen = Substring_Length(args->lhs);
        if (args->pflags.anchorStart) {
                if (wordLen < lhsLen ||
-                   memcmp(word, args->lhs.start, lhsLen) != 0)
+                   memcmp(word.start, args->lhs.start, lhsLen) != 0)
                        goto nosub;
 
                if (args->pflags.anchorEnd && wordLen != lhsLen)
                        goto nosub;
 
                /* :S,^prefix,replacement, or :S,^whole$,replacement, */
-               SepBuf_AddBytesBetween(buf, args->rhs.start, args->rhs.end);
-               SepBuf_AddBytesBetween(buf, word + lhsLen, wordEnd);
+               SepBuf_AddSubstring(buf, args->rhs);
+               SepBuf_AddBytesBetween(buf, word.start + lhsLen, wordEnd);
                args->matched = true;
                return;
        }
@@ -1599,8 +1612,8 @@
                        goto nosub;
 
                /* :S,suffix$,replacement, */
-               SepBuf_AddBytesBetween(buf, word, wordEnd - lhsLen);
-               SepBuf_AddBytesBetween(buf, args->rhs.start, args->rhs.end);
+               SepBuf_AddBytesBetween(buf, word.start, wordEnd - lhsLen);
+               SepBuf_AddSubstring(buf, args->rhs);
                args->matched = true;
                return;
        }
@@ -1609,17 +1622,16 @@
                goto nosub;
 
        /* unanchored case, may match more than once */
-       while ((match = Substring_Find(Substring_Init(word, wordEnd),
-           args->lhs)) != NULL) {
-               SepBuf_AddBytesBetween(buf, word, match);
-               SepBuf_AddBytesBetween(buf, args->rhs.start, args->rhs.end);
+       while ((match = Substring_Find(word, args->lhs)) != NULL) {
+               SepBuf_AddBytesBetween(buf, word.start, match);
+               SepBuf_AddSubstring(buf, args->rhs);
                args->matched = true;
-               word += (size_t)(match - word) + lhsLen;
-               if (word == wordEnd || !args->pflags.subGlobal)
+               word.start += (size_t)(match - word.start) + lhsLen;
+               if (Substring_IsEmpty(word) || !args->pflags.subGlobal)
                        break;
        }



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