checkstack: Handle conditional checks at start of functions

Recent versions of gcc will sometimes place conditional checks in the
code prior to setting up the function's stack frame.  Handle this case
correctly.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

diff --git a/scripts/checkstack.py b/scripts/checkstack.py
index 5d9b0bfaf304d7d4b2a6d6c8128ad7f61ac807ec..255768aebce0341f0bb06d13973e653735aa5154 100755 (executable)
--- a/scripts/checkstack.py
+++ b/scripts/checkstack.py
@@ -153,6 +153,11 @@ def main():
             if '%esp' in insn or insn.startswith('leal'):
                 # Still part of initial header
                 continue
+            if not stackusage and (
+                    insn.startswith('test') or insn.startswith('cmp')
+                    or insn.startswith('j')):
+                # There may be conditional checks prior to stack frame
+                continue
             cur.basic_stack_usage = stackusage
             atstart = 0