[src/trunk]: src/usr.bin/make make: migrate handling of the modifier ':S,from...

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2c2d900e9438
branches:  trunk
changeset: 982363:2c2d900e9438
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Apr 11 17:48:01 2021 +0000

description:
make: migrate handling of the modifier ':S,from,to,' to Substring

Right now this does not gain any performance, it only makes the code in
ModifyWord_Subst a little simpler since it only uses
Buf_AddBytesBetween, not a mixture with Buf_AddBytes.

When the word passed to the ModifyWord functions is converted to
Substring as well, the call to strlen will become redundant.

No functional change.

diffstat:

 usr.bin/make/var.c |  88 ++++++++++++++++++++++++++++++-----------------------
 1 files changed, 49 insertions(+), 39 deletions(-)

diffs (186 lines):

diff -r 4be3492fc253 -r 2c2d900e9438 usr.bin/make/var.c
--- a/usr.bin/make/var.c        Sun Apr 11 16:21:04 2021 +0000
+++ b/usr.bin/make/var.c        Sun Apr 11 17:48:01 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: var.c,v 1.917 2021/04/11 13:35:56 rillig Exp $ */
+/*     $NetBSD: var.c,v 1.918 2021/04/11 17:48:01 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 1.917 2021/04/11 13:35:56 rillig Exp $");
+MAKE_RCSID("$NetBSD: var.c,v 1.918 2021/04/11 17:48:01 rillig Exp $");
 
 /*
  * Variables are defined using one of the VAR=value assignments.  Their
@@ -1541,14 +1541,25 @@
 
 
 struct ModifyWord_SubstArgs {
-       const char *lhs;
-       size_t lhsLen;
-       const char *rhs;
-       size_t rhsLen;
+       Substring lhs;
+       Substring rhs;
        VarPatternFlags pflags;
        bool matched;
 };
 
+static const char *
+Substring_Find(Substring haystack, Substring needle)
+{
+       size_t len, needleLen, i;
+
+       len = Substring_Length(haystack);
+       needleLen = Substring_Length(needle);
+       for (i = 0; i + needleLen <= len; i++)
+               if (memcmp(haystack.start + i, needle.start, needleLen) == 0)
+                       return haystack.start + i;
+       return NULL;
+}
+
 /*
  * Callback for ModifyWords to implement the :S,from,to, modifier.
  * Perform a string substitution on the given word.
@@ -1556,61 +1567,59 @@
 static void
 ModifyWord_Subst(const char *word, SepBuf *buf, void *data)
 {
-       size_t wordLen = strlen(word);
        struct ModifyWord_SubstArgs *args = data;
-       const char *match;
-
+       size_t wordLen, lhsLen;
+       const char *wordEnd, *match;
+
+       wordLen = strlen(word);
+       wordEnd = word + wordLen;
        if (args->pflags.subOnce && args->matched)
                goto nosub;
 
+       lhsLen = Substring_Length(args->lhs);
        if (args->pflags.anchorStart) {
-               if (wordLen < args->lhsLen ||
-                   memcmp(word, args->lhs, args->lhsLen) != 0)
+               if (wordLen < lhsLen ||
+                   memcmp(word, args->lhs.start, lhsLen) != 0)
                        goto nosub;
 
-               if (args->pflags.anchorEnd && wordLen != args->lhsLen)
+               if (args->pflags.anchorEnd && wordLen != lhsLen)
                        goto nosub;
 
                /* :S,^prefix,replacement, or :S,^whole$,replacement, */
-               SepBuf_AddBytes(buf, args->rhs, args->rhsLen);
-               SepBuf_AddBytesBetween(buf,
-                   word + args->lhsLen, word + wordLen);
+               SepBuf_AddBytesBetween(buf, args->rhs.start, args->rhs.end);
+               SepBuf_AddBytesBetween(buf, word + lhsLen, wordEnd);
                args->matched = true;
                return;
        }
 
        if (args->pflags.anchorEnd) {
-               const char *start;
-
-               if (wordLen < args->lhsLen)
+               if (wordLen < lhsLen)
                        goto nosub;
-
-               start = word + (wordLen - args->lhsLen);
-               if (memcmp(start, args->lhs, args->lhsLen) != 0)
+               if (memcmp(wordEnd - lhsLen, args->lhs.start, lhsLen) != 0)
                        goto nosub;
 
                /* :S,suffix$,replacement, */
-               SepBuf_AddBytesBetween(buf, word, start);
-               SepBuf_AddBytes(buf, args->rhs, args->rhsLen);
+               SepBuf_AddBytesBetween(buf, word, wordEnd - lhsLen);
+               SepBuf_AddBytesBetween(buf, args->rhs.start, args->rhs.end);
                args->matched = true;
                return;
        }
 
-       if (args->lhs[0] == '\0')
+       if (args->lhs.start[0] == '\0')
                goto nosub;
 
        /* unanchored case, may match more than once */
-       while ((match = strstr(word, args->lhs)) != NULL) {
+       while ((match = Substring_Find(Substring_Init(word, wordEnd),
+           args->lhs)) != NULL) {
                SepBuf_AddBytesBetween(buf, word, match);
-               SepBuf_AddBytes(buf, args->rhs, args->rhsLen);
+               SepBuf_AddBytesBetween(buf, args->rhs.start, args->rhs.end);
                args->matched = true;
-               wordLen -= (size_t)(match - word) + args->lhsLen;
-               word += (size_t)(match - word) + args->lhsLen;
-               if (wordLen == 0 || !args->pflags.subGlobal)
+               word += (size_t)(match - word) + lhsLen;
+               if (word == wordEnd || !args->pflags.subGlobal)
                        break;
        }
 nosub:
-       SepBuf_AddBytes(buf, word, wordLen);
+       SepBuf_AddBytesBetween(buf, word, wordEnd);
 }
 
 #ifndef NO_REGEX
@@ -2189,9 +2198,9 @@
     VarEvalMode emode,
     ModChain *ch,
     char **out_part,
-    /* Optionally stores the length of the returned string, just to save
+    /* Optionally stores the end of the returned string, just to save
      * another strlen call. */
-    size_t *out_length,
+    const char **out_part_end,
     /* For the first part of the :S modifier, sets the VARP_ANCHOR_END flag
      * if the last character of the pattern is a $. */
     VarPatternFlags *out_pflags,
@@ -2221,7 +2230,8 @@
 
                if (*p != '$') {        /* Unescaped, simple text */
                        if (subst != NULL && *p == '&')
-                               Buf_AddBytes(&buf, subst->lhs, subst->lhsLen);
+                               Buf_AddBytesBetween(&buf,
+                                   subst->lhs.start, subst->lhs.end);
                        else
                                Buf_AddByte(&buf, *p);
                        p++;
@@ -2299,8 +2309,8 @@
        }
 
        *pp = p + 1;
-       if (out_length != NULL)
-               *out_length = buf.len;
+       if (out_part_end != NULL)
+               *out_part_end = buf.data + buf.len;
 
        *out_part = Buf_DoneData(&buf);
        DEBUG1(VAR, "Modifier part: \"%s\"\n", *out_part);
@@ -2931,16 +2941,16 @@
        }
 
        res = ParseModifierPartSubst(pp, delim, ch->expr->emode, ch, &lhs,
-           &args.lhsLen, &args.pflags, NULL);
+           &args.lhs.end, &args.pflags, NULL);
        if (res != VPR_OK)
                return AMR_CLEANUP;
-       args.lhs = lhs;
+       args.lhs.start = lhs;
 
        res = ParseModifierPartSubst(pp, delim, ch->expr->emode, ch, &rhs,
-           &args.rhsLen, NULL, &args);
+           &args.rhs.end, NULL, &args);
        if (res != VPR_OK)
                return AMR_CLEANUP;
-       args.rhs = rhs;
+       args.rhs.start = rhs;
 
        oneBigWord = ch->oneBigWord;
        ParsePatternFlags(pp, &args.pflags, &oneBigWord);