[llvm] r208257 - [RuntimeDyld] Make RuntimeDyldImpl::resolveExternalSymbols preserve the
David Blaikie
dblaikie at gmail.com
Wed May 7 16:16:10 PDT 2014
On Wed, May 7, 2014 at 3:34 PM, Lang Hames <lhames at gmail.com> wrote:
> Author: lhames
> Date: Wed May 7 17:34:08 2014
> New Revision: 208257
>
> URL: http://llvm.org/viewvc/llvm-project?rev=208257&view=rev
> Log:
> [RuntimeDyld] Make RuntimeDyldImpl::resolveExternalSymbols preserve the
> relocation entries it applies.
>
> Prior to this patch, RuntimeDyldImpl::resolveExternalSymbols discarded
> relocations for external symbols once they had been applied. This causes issues
> if the client calls MCJIT::finalizeLoadedModules more than once, and updates the
> location of any symbols in between (e.g. by calling MCJIT::mapSectionAddress).
>
> No test case yet: None of our in-tree memory managers support moving sections
> around. I'll have to hack up a dummy memory manager before I can write a unit
> test.
>
> Fixes <rdar://problem/16764378>
>
>
> Modified:
> llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
>
> Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp?rev=208257&r1=208256&r2=208257&view=diff
> ==============================================================================
> --- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp (original)
> +++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp Wed May 7 17:34:08 2014
> @@ -620,6 +620,8 @@ void RuntimeDyldImpl::resolveRelocationL
> }
>
> void RuntimeDyldImpl::resolveExternalSymbols() {
> + StringMap<RelocationList> ProcessedSymbols;
> +
> while (!ExternalSymbolRelocations.empty()) {
> StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin();
>
> @@ -665,8 +667,20 @@ void RuntimeDyldImpl::resolveExternalSym
> resolveRelocationList(Relocs, Addr);
> }
>
> + ProcessedSymbols[i->first()] = i->second;
> ExternalSymbolRelocations.erase(i);
> }
> +
> + // Restore the relocation entries that were consumed in the loop above:
> + //
> + // FIXME: Replace the following loop with:
> + // std::swap(ProcessedSymbols, ExternalSymbolRelocations)
Presumably just: ExternalSymbolRelocations = std::move(ProcessedSymbols);
swap was what you had to use for this back in C++98 when there were no
move semantics.
(but, yes, in either case, StringMap needs move semantic support to
rewrite it that way)
> + // once StringMap has copy and move construction.
> + for (StringMap<RelocationList>::iterator I = ProcessedSymbols.begin(),
> + E = ProcessedSymbols.end();
> + I != E; ++I) {
> + ExternalSymbolRelocations[I->first()] = I->second;
But this code looks about as expensive as a copy anyway, so why not
just write this as suggested above (Ext = std::move(Proc);) and then
it'll just get 'better' if/when StringMap grows move semantics?
> + }
> }
>
> //===----------------------------------------------------------------------===//
>
>
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