Fix performance degradation introduced by the second expansion feature.

I did this by adding intelligence into the algorithm such that the
second expansion was only actually performed when the prerequisite list
contained at least one "$", so we knew it is actually needed.

Without this we were using up a LOT more memory, since every single
target (even ones never used by make) had their file variables
initialized.  This also used a lot more CPU, since we needed to create
and populate a new variable hash table for every target.

There is one issue remaining with this feature: it leaks memory.  In
pattern_search() we now initialize the file variables for every pattern
target, which allocates a hash table, etc.  However, sometimes we
recursively invoke pattern_search() (for intermediate files) with an
automatic variable (alloca() I believe) as the file.  When that function
returns, obviously, the file variable hash memory is lost.

1 files changed, 2 insertions, 0 deletions

diff --git a/main.c b/main.c
index 014c41f..b99bf27 100644
--- a/main.c
+++ b/main.c
@@ -2125,6 +2125,7 @@ main (int argc, char **argv, char **envp)
             goals->next = 0;
             goals->name = 0;
             goals->ignore_mtime = 0;
+            goals->need_2nd_expansion = 0;
             goals->file = default_goal_file;
           }
       }
@@ -2290,6 +2291,7 @@ handle_non_switch_argument (char *arg, int env)
       lastgoal->name = 0;
       lastgoal->file = f;
       lastgoal->ignore_mtime = 0;
+      lastgoal->need_2nd_expansion = 0;
 
       {
         /* Add this target name to the MAKECMDGOALS variable. */