[PATCH] D58431: SanitizerCommon: fixes for unwinding & backtrace on SPARC

[Eric Botcazou via Phabricator via llvm-commits]

ebotcazou marked 2 inline comments as done.
ebotcazou added inline comments.


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Comment at: compiler-rt/lib/sanitizer_common/sanitizer_stacktrace_sparc.cc:35
+  // on the SPARC and not the return address, so we need to compensate.
+  trace_buffer[0] = GetNextInstructionPc(pc);
+#else
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vitalybuka wrote:
> I am not sure that we need to compensate here
> usually it's from GetStackTrace which pass the current PC or PC from signal
Yes, we do, the backtrace does GetPreviousInstructionPc in every case so, if you don' t do it there too, then the backtrace is wrong.



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Comment at: compiler-rt/lib/sanitizer_common/sanitizer_unwind_linux_libcdep.cc:139
+#if defined(__GNUC__) && defined(__sparc__)
+  // __builtin_return_address returns the address of the call instruction
+  // on the SPARC and not the return address, so we need to compensate.
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vitalybuka wrote:
> that's strange
> is this know issue?
Yes, it's a known historical quirk on the SPARC.  The root cause is probably that, in 32-bit mode, the return address is either %o7+8 or %o7+12 depending on the return type and the correct case isn't always easy to spot.  That's not the case in 64-bit mode, but the usage was preserved, for the sake of consistency I presume.




Repository:
  rCRT Compiler Runtime

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  https://reviews.llvm.org/D58431/new/

https://reviews.llvm.org/D58431