[PATCH v3] covoar: Handle periods in symbols from objdump

[Gedare Bloom]

On Tue, Mar 16, 2021 at 8:25 AM Alex White <alex.white at oarcorp.com> wrote:
>
> Occasionally the compiler will generate symbols that look similar to
> symbols defined in RTEMS code except that they contain some suffix.
> These symbol suffixes are only found in the ELF symbol table; the
> symbols appear to be normal in the DWARF info. This appears to be
> happening on all architectures.
>
> For example, the function _Message_queue_Create from rtems appears as
> "_Message_queue_Create.part.0". Other suffixes include ".isra.0",
> ".constprop.0", and ".0".
>

Do any non-compiler-generated symbols include "."?

Are there symbols that start with a "." that might be caught? I know
we do this in assembly programming often, e.g., ".vectors", although
probably it is unlikely to appear in C/asm I just want to be thorough.

> This looks to be related to compiler optimizations. Symbols with
> suffixes were being treated as unique. For our purposes, they should be
> mapped to the equivalent symbols in the DWARF info. This has been
> fixed.
> ---
>  tester/covoar/ExecutableInfo.cc   | 22 +++++++++++++++++++---
>  tester/covoar/ObjdumpProcessor.cc |  6 ++++++
>  tester/covoar/SymbolTable.cc      | 12 +++++++++---
>  3 files changed, 34 insertions(+), 6 deletions(-)
>
> diff --git a/tester/covoar/ExecutableInfo.cc b/tester/covoar/ExecutableInfo.cc
> index c996d75..9384973 100644
> --- a/tester/covoar/ExecutableInfo.cc
> +++ b/tester/covoar/ExecutableInfo.cc
> @@ -118,8 +118,7 @@ namespace Coverage {
>      // Obtain the coverage map containing the specified address.
>      itsSymbol = theSymbolTable.getSymbol( address );
>      if (itsSymbol != "") {
> -      it = coverageMaps.find( itsSymbol );
> -      aCoverageMap = (*it).second;
> +      aCoverageMap = &findCoverageMap(itsSymbol);
>      }
>
>      return aCoverageMap;
> @@ -150,8 +149,25 @@ namespace Coverage {
>    )
>    {
>      CoverageMaps::iterator cmi = coverageMaps.find( symbolName );
> -    if ( cmi == coverageMaps.end() )
> +    if ( cmi != coverageMaps.end() ) {
> +      return *(cmi->second);
> +    }
> +
> +    size_t periodIndex = symbolName.find(".");
> +
> +    if (periodIndex == std::string::npos) {
> +      // Symbol name has no '.', can't do another lookup.
>        throw CoverageMapNotFoundError(symbolName);
> +    }
> +
> +    cmi = coverageMaps.find(
> +      symbolName.substr(0, periodIndex)
> +    );
> +
> +    if ( cmi == coverageMaps.end() ) {
> +      throw CoverageMapNotFoundError(symbolName);
> +    }
> +
>      return *(cmi->second);
>    }
>
> diff --git a/tester/covoar/ObjdumpProcessor.cc b/tester/covoar/ObjdumpProcessor.cc
> index fa9894d..544bfa1 100644
> --- a/tester/covoar/ObjdumpProcessor.cc
> +++ b/tester/covoar/ObjdumpProcessor.cc
> @@ -417,6 +417,12 @@ namespace Coverage {
>          processSymbol = false;
>          theInstructions.clear();
>
> +        // Look for a '.' character and strip everything after it.
> +        char *periodIndex = strstr(symbol, ".");
> +        if (periodIndex != NULL) {
> +          *periodIndex = 0;
> +        }
> +
>          // See if the new symbol is one that we care about.
>          if (SymbolsToAnalyze->isDesired( symbol )) {
>            currentSymbol = symbol;
> diff --git a/tester/covoar/SymbolTable.cc b/tester/covoar/SymbolTable.cc
> index 53bc8af..00062cc 100644
> --- a/tester/covoar/SymbolTable.cc
> +++ b/tester/covoar/SymbolTable.cc
> @@ -46,12 +46,18 @@ namespace Coverage {
>      symbolData.startingAddress = start;
>      symbolData.length = length;
>
> -    if ( info[ symbol ].empty() == false ) {
> -      if ( info[ symbol ].front().length != length ) {
> +    for (auto& symData : info[ symbol ]) {
> +      // The starting address could differ since we strip any suffixes beginning
> +      // with a '.'
> +      if (symData.startingAddress != start) {
> +        continue;
> +      }
> +
> +      if (symData.length != length) {
>          std::ostringstream what;
>          what << "Different lengths for the symbol "
>               << symbol
> -             << " (" << info[ symbol ].front().length
> +             << " (" << symData.length
>               << " and " << length
>               << ")";
>          throw rld::error( what, "SymbolTable::addSymbol" );
> --
> 2.27.0
>
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