mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-16 11:30:51 +00:00
3e19a9ee9f
Current PPC64 RuntimeDyld code to handle TOC relocations has two problems: - With recent linkers, in addition to the relocations that implicitly refer to the TOC base (R_PPC64_TOC*), you can now also use the .TOC. magic symbol with any other relocation to refer to the TOC base explicitly. This isn't currently used much in ELFv1 code (although it could be), but it is essential in ELFv2 code. - In a complex JIT environment with multiple modules, each module may have its own .toc section, and TOC relocations in one module must refer to *its own* TOC section. The current findPPC64TOC implementation does not correctly implement this; in fact, it will always return the address of the first TOC section it finds anywhere. (Note that at the time findPPC64TOC is called, we don't even *know* which module the relocation originally resided in, so it is not even possible to fix this routine as-is.) This commit fixes both problems by handling TOC relocations earlier, in processRelocationRef. To do this, I've removed the findPPC64TOC routine and replaced it by a new routine findPPC64TOCSection, which works analogously to findOPDEntrySection in scanning the sections of the ObjImage provided by its caller, processRelocationRef. This solves the issue of finding the correct TOC section associated with the current module. This makes it straightforward to implement both R_PPC64_TOC relocations, and relocations explicitly refering to the .TOC. symbol, directly in processRelocationRef. There is now a new problem in implementing the R_PPC64_TOC16* relocations, because those can now in theory involve *three* different sections: the relocation may be applied in section A, refer explicitly to a symbol in section B, and refer implicitly to the TOC section C. The final processing of the relocation thus may only happen after all three of these sections have been assigned final addresses. There is currently no obvious means to implement this in its general form with the common-code RuntimeDyld infrastructure. Fortunately, ppc64 code usually makes no use of this most general form; in fact, TOC16 relocations are only ever generated by LLVM for symbols residing themselves in the TOC, which means "section B" == "section C" in the above terminology. This special case can easily be handled with the current infrastructure, and that is what this patch does. [ Unhandled cases result in an explicit error, unlike the current code which silently returns the wrong TOC base address ... ] This patch makes the JIT work on both BE and LE (ELFv2 requires additional patches, of course), and allowed me to successfully run complex JIT scenarios (via mesa/llvmpipe). Reviewed by Hal Finkel. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211885 91177308-0d34-0410-b5e6-96231b3b80d8 |
||
|---|---|---|
| .. | ||
| Analysis | ||
| AsmParser | ||
| Bitcode | ||
| CodeGen | ||
| DebugInfo | ||
| ExecutionEngine | ||
| IR | ||
| IRReader | ||
| LineEditor | ||
| Linker | ||
| LTO | ||
| MC | ||
| Object | ||
| Option | ||
| ProfileData | ||
| Support | ||
| TableGen | ||
| Target | ||
| Transforms | ||
| CMakeLists.txt | ||
| LLVMBuild.txt | ||
| Makefile | ||