RFR: JDK-8254889: name_and_sig_as_C_string usages in frame coding without ResourceMark

[Matthias Baesken]

On Fri, 16 Oct 2020 12:46:32 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Hello, seems we have some usages of name_and_sig_as_C_string() in frame related HS coding without using a ResourceMark.
>> Please review.
>> Thanks, Matthias
>
> src/hotspot/share/runtime/frame.cpp line 1145:
> 
>> 1143: #ifndef PRODUCT
>> 1144: void frame::describe(FrameValues& values, int frame_no) {
>> 1145:   ResourceMark rm;
> 
> Not sure this works. RA allocated memory escapes the function in FrameValues::describe() (via FrameValue::description):
> 
> void FrameValues::describe(int owner, intptr_t* location, const char* description, int priority) {
>   FrameValue fv;
>   fv.location = location;
>   fv.owner = owner;
>   fv.priority = priority;
>   fv.description = NEW_RESOURCE_ARRAY(char, strlen(description) + 1);
>   strcpy(fv.description, description);
>   _values.append(fv);
> }

Okay thanks , we have to take escaping memory indeed into consideration .
 I  think I should omit the frame_zero.cpp  change.
In frame.cpp I could use a local buffer (any idea  how large?)  and the name_and_sig_as_C_string-version taking a
pre-allocated buffer :   name_and_sig_as_C_string(buffer, buf_len)   . Then there is not need to add the  ResourceMark
, correct ?

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PR: https://git.openjdk.java.net/jdk/pull/698