Issue #4753: By enabling a configure option named '--with-computed-gotos'

on compilers that support it (notably: gcc, SunPro, icc), the bytecode
evaluation loop is compiled with a new dispatch mechanism which gives
speedups of up to 20%, depending on the system, on various benchmarks.

1 files changed, 16 insertions, 0 deletions

diff --git a/configure.in b/configure.in
index 12e4c80..a29a4c5 100644
--- a/configure.in
+++ b/configure.in
@@ -3660,6 +3660,22 @@ then
    wide chars that would be converted.])
 fi
 
+# Check for --with-computed-gotos
+AC_MSG_CHECKING(for --with-computed-gotos)
+AC_ARG_WITH(computed-gotos,
+            AC_HELP_STRING(--with-computed-gotos,
+                           Use computed gotos / threaded dispatch in evaluation loop (not available on all compilers)),
+[
+if test "$withval" != no
+then 
+  AC_DEFINE(USE_COMPUTED_GOTOS, 1,
+  [Define if you want to use computed gotos in ceval.c.]) 
+  AC_MSG_RESULT(yes)
+else AC_MSG_RESULT(no)
+fi],
+[AC_MSG_RESULT(no)])
+
+
 AC_SUBST(THREADHEADERS)
 
 for h in `(cd $srcdir;echo Python/thread_*.h)`