Merge pull request #798 from kmod/section_ordering

section ordering hack: use the PGO-determined ordering

tools/generate_section_ordering_from_pgo_build.py

+"""
+This script attempts to generate a section_ordering.txt file
+based on how gcc decided to lay out the pgo build.
+"""
+
+import subprocess
+import sys
+
+"""
+typical usage:
+    make perf_combined
+    make pyston_pgo
+    python tools/generate_section_ordering_from_pgo_build.py pyston_pgo perf.data > section_ordering.txt
+"""
+
+if __name__ == "__main__":
+    assert len(sys.argv) == 3, "Usage: %s PGO_BINARY PERF_DATA" % sys.argv[0]
+    binary = sys.argv[1]
+    perf_data = sys.argv[2]
+
+    perf_results = subprocess.check_output(["perf", "report", "-i", perf_data, "--no-demangle", "-g",
+        "none", "--percent-limit", "0.0"])
+
+    functions_in_perf = set([])
+    for l in perf_results.split('\n'):
+        l = l.strip()
+        if not l:
+            continue
+        if not l[0].isdigit():
+            continue
+        func_name = l.rsplit(' ', 1)[1]
+        if func_name.startswith('0x0'):
+            continue
+        functions_in_perf.add(func_name)
+
+    print >>sys.stderr, "%d functions in the perf results" % len(functions_in_perf)
+    nm_output = subprocess.check_output(["nm", binary]).split('\n')
+
+    functions = []
+    for l in nm_output:
+        if not l:
+            continue
+        if not l[0].isalnum():
+            continue
+        addr, type, name = l.split()
+        if type not in 'tT':
+            continue
+
+        if name not in functions_in_perf:
+            continue
+
+        functions.append((int(addr, 16), name))
+    functions.sort()
+
+    for l in functions:
+        print ".text." + l[1]