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.
diff --git a/Python/makeopcodetargets.py b/Python/makeopcodetargets.py
new file mode 100644
index 0000000..6b1ab43
--- /dev/null
+++ b/Python/makeopcodetargets.py
@@ -0,0 +1,43 @@
+#! /usr/bin/env python
+"""Generate C code for the jump table of the threaded code interpreter
+(for compilers supporting computed gotos or "labels-as-values", such as gcc).
+"""
+
+import imp
+import os
+
+
+def find_module(modname):
+ """Finds and returns a module in the local dist/checkout.
+ """
+ modpath = os.path.join(
+ os.path.dirname(os.path.dirname(__file__)), "Lib")
+ return imp.load_module(modname, *imp.find_module(modname, [modpath]))
+
+def write_contents(f):
+ """Write C code contents to the target file object.
+ """
+ opcode = find_module("opcode")
+ targets = ['_unknown_opcode'] * 256
+ for opname, op in opcode.opmap.items():
+ if opname == "STOP_CODE":
+ # XXX opcode not implemented
+ continue
+ targets[op] = "TARGET_%s" % opname
+ f.write("static void *opcode_targets[256] = {\n")
+ f.write(",\n".join("\t&&%s" % s for s in targets))
+ f.write("\n};\n")
+
+
+if __name__ == "__main__":
+ import sys
+ assert len(sys.argv) < 3, "Too many arguments"
+ if len(sys.argv) == 2:
+ target = sys.argv[1]
+ else:
+ target = "Python/opcode_targets.h"
+ f = open(target, "w")
+ try:
+ write_contents(f)
+ finally:
+ f.close()