[gcc(refs/users/marxin/heads/fixinclude-speed-up)] Speed up fixincludes.

[Martin Liska <marxin@gcc.gnu.org>]

https://gcc.gnu.org/g:0ba77db8a29ad1d98937d1deedbe1ad86638fc23

commit 0ba77db8a29ad1d98937d1deedbe1ad86638fc23
Author: Martin Liska <mliska@suse.cz>
Date:   Thu Feb 3 15:49:43 2022 +0100

    Speed up fixincludes.
    
    In my case:
    $ rm ./stmp-fixinc ; time make -j16
    
    takes 17 seconds, where I can reduce it easily with the suggested
    change. Then I get to 11.2 seconds.
    
    The scripts searches ~2500 folders in my case with total 20K header
    files.
    
    fixincludes/ChangeLog:
    
            * fixinc.in: Use mkdir -p rather that a loop.

Diff:
---
 fixincludes/fixinc.in | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/fixincludes/fixinc.in b/fixincludes/fixinc.in
index de5a37f6acc..92f3dfc39a9 100755
--- a/fixincludes/fixinc.in
+++ b/fixincludes/fixinc.in
@@ -258,12 +258,23 @@ then echo "All directories (including links to directories):"
      echo $all_dirs
 fi
 
-for file in $all_dirs; do
-  rm -rf $LIB/$file
-  if [ ! -d $LIB/$file ]
-  then mkdir $LIB/$file
-  fi
-done
+ARG_MAX=`getconf ARG_MAX 2>/dev/null`
+LENGTH=`expr length "$all_dirs" + 10`
+
+if test -n "$ARG_MAX" && test $LENGTH -lt $ARG_MAX
+then
+  cd $LIB
+  mkdir -p $all_dirs
+  cd ..
+else
+  for file in $all_dirs; do
+    rm -rf $LIB/$file
+    if [ ! -d $LIB/$file ]
+    then mkdir $LIB/$file
+    fi
+  done
+fi
+
 mkdir $LIB/root
 
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