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[Go] Make sure that arguments for which use memcpy when calling C are

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still live after the call.  This ensures that they will not be
collected if the GC runs during the call.
This commit is contained in:
Ian Lance Taylor 2015-05-04 15:11:31 -07:00
commit 48263f4802
4 changed files with 77 additions and 34 deletions
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28
Source/Modules/go.cxx
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@ -2035,7 +2035,7 @@ private:
* needs to explicitly escape. This is true if the parameter has a
* non-empty argout or freearg typemap, because in those cases the
* Go argument might be or contain a pointer. We need to ensure
* that that pointer does not oint into the stack, which means that
* that that pointer does not point into the stack, which means that
* it needs to escape.
* ---------------------------------------------------------------------- */
bool paramNeedsEscape(Parm *p) {
@ -2502,6 +2502,28 @@ private:
p = Getattr(p, "tmap:goargout:next");
}
}
// When using cgo, if we need to memcpy a parameter to pass it to
// the C code, the compiler may think that the parameter is not
// live during the function call. If the garbage collector runs
// while the C/C++ function is running, the parameter may be
// freed. Force the compiler to see the parameter as live across
// the C/C++ function.
if (cgo_flag) {
int parm_count = emit_num_arguments(parms);
p = parms;
for (int i = 0; i < parm_count; ++i) {
p = getParm(p);
bool c_struct_type;
Delete(cgoTypeForGoValue(p, Getattr(p, "type"), &c_struct_type));
if (c_struct_type) {
Printv(f_go_wrappers, "\tif Swig_escape_always_false {\n", NULL);
Printv(f_go_wrappers, "\t\tSwig_escape_val = ", Getattr(p, "emit:goinput"), "\n", NULL);
Printv(f_go_wrappers, "\t}\n", NULL);
}
p = nextParm(p);
}
}
}
/* -----------------------------------------------------------------------
@ -3537,6 +3559,8 @@ private:
DelWrapper(dummy);
Swig_typemap_attach_parms("gotype", parms, NULL);
Swig_typemap_attach_parms("goin", parms, NULL);
Swig_typemap_attach_parms("goargout", parms, NULL);
Swig_typemap_attach_parms("imtype", parms, NULL);
int parm_count = emit_num_arguments(parms);
@ -3689,6 +3713,8 @@ private:
Printv(f_go_wrappers, call, "\n", NULL);
goargout(parms);
Printv(f_go_wrappers, "\treturn p\n", NULL);
Printv(f_go_wrappers, "}\n\n", NULL);