Author: Armin Rigo <[email protected]>
Branch:
Changeset: r90572:4c7864396507
Date: 2017-03-05 21:33 +0100
http://bitbucket.org/pypy/pypy/changeset/4c7864396507/
Log: bug fix (memory corruption showing up from a cond_call_value_r)
diff --git a/rpython/jit/backend/x86/regalloc.py
b/rpython/jit/backend/x86/regalloc.py
--- a/rpython/jit/backend/x86/regalloc.py
+++ b/rpython/jit/backend/x86/regalloc.py
@@ -948,11 +948,11 @@
# If this also contains args[0], this returns the current
# location too.
arglocs = [self.loc(args[i]) for i in range(2, len(args))]
- gcmap = self.get_gcmap()
if op.type == 'v':
# a plain COND_CALL. Calls the function when args[0] is
# true. Often used just after a comparison operation.
+ gcmap = self.get_gcmap()
self.load_condition_into_cc(op.getarg(0))
resloc = None
else:
@@ -969,6 +969,22 @@
resloc = self.rm.force_result_in_reg(op, args[0],
forbidden_vars=args[2:])
+ # Get the gcmap here, possibly including the spilled
+ # location, and always excluding the 'resloc' register.
+ # Some more details: the only interesting case is the case
+ # where we're doing the call (if we are not, the gcmap is
+ # not used); and in this case, the gcmap must include the
+ # spilled location (it contains a valid GC pointer to fix
+ # during the call if a GC occurs), and never 'resloc'
+ # (it will be overwritten with the result of the call, which
+ # is not computed yet if a GC occurs).
+ #
+ # (Note that the spilled value is always NULL at the moment
+ # if the call really occurs, but it's not worth the effort to
+ # not list it in the gcmap and get crashes if we tweak
+ # COND_CALL_VALUE_R in the future)
+ gcmap = self.get_gcmap([resloc])
+
# Test the register for the result.
self.assembler.test_location(resloc)
self.assembler.guard_success_cc = rx86.Conditions['Z']
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