Fix gdb.trace/mi-traceframe-changed.exp on s390.
The test fails on s390 with: -trace-find frame-number 0^M &"PC not available\n"^M ^done,found="1",tracepoint="1",traceframe="0",frame={level="-1",addr="<unavailable>",func="??",args=[]}^M (gdb) ^M FAIL: gdb.trace/mi-traceframe-changed.exp: tfile: -trace-find frame-number 0 tfile knows to infer the PC from the tracepoint's address if the PC wasn't collected (tfile_fetch_registers) but, that only works on targets whose PC register is a raw register, and on s390, the PC register is a pseudo register. But even if GDB doesn't know how to infer the value of PC, saying the current frame is level -1 is a bug: ^done,found="1",tracepoint="1",traceframe="0",frame={level="-1",addr="<unavailable>",func="??",args=[]}^M ^^^^^^^^^ '-1' is the level of the sentinel frame, which should never be visible. This is caused by the s390's heuristic unwinder accepting the frame (the fallback heuristic unwinders _always_ accept the frame), but then the unwind->this_id method throws that "PC not available\n" error. IOW, the s390's heuristic unwinder was never adjusted to handle unavailable register values gracefully, which can happen with e.g., a trimmed core file too. This is just the minimal necessary for <unavailable> frames, which at least gets us: (gdb) tfind Found trace frame 0, tracepoint 1 #0 <unavailable> in ?? () That is, frame #0 instead of -1. We could get better info out of "info frame" (this patch makes us show "outermost"), but this change would still be necessary. gdb/ 2014-01-16 Pedro Alves <palves@redhat.com> * s390-linux-tdep.c (s390_frame_unwind_cache): Swallow NOT_AVAILABLE_ERROR errors while parsing the prologue or reading the backchain.
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@ -1,3 +1,9 @@
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2014-01-16 Pedro Alves <palves@redhat.com>
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* s390-linux-tdep.c (s390_frame_unwind_cache): Swallow
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NOT_AVAILABLE_ERROR errors while parsing the prologue or reading
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the backchain.
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2014-01-16 Doug Evans <dje@google.com>
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* dwarf2read.c (open_and_init_dwp_file): Fix typo in comment.
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@ -2039,7 +2039,9 @@ static struct s390_unwind_cache *
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s390_frame_unwind_cache (struct frame_info *this_frame,
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void **this_prologue_cache)
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{
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volatile struct gdb_exception ex;
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struct s390_unwind_cache *info;
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if (*this_prologue_cache)
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return *this_prologue_cache;
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@ -2050,10 +2052,15 @@ s390_frame_unwind_cache (struct frame_info *this_frame,
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info->frame_base = -1;
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info->local_base = -1;
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TRY_CATCH (ex, RETURN_MASK_ERROR)
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{
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/* Try to use prologue analysis to fill the unwind cache.
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If this fails, fall back to reading the stack backchain. */
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if (!s390_prologue_frame_unwind_cache (this_frame, info))
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s390_backchain_frame_unwind_cache (this_frame, info);
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}
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if (ex.reason < 0 && ex.error != NOT_AVAILABLE_ERROR)
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throw_exception (ex);
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return info;
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}
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