mstorsjo added a comment. In https://reviews.llvm.org/D43184#1038129, @rnk wrote:
> In https://reviews.llvm.org/D43184#1031831, @mstorsjo wrote: > > > So in case this approach as my hacky PoC does is the only feasible way > > left, I obviously need to fix it up. Any directions and suggestions on how > > to structure it properly? And suggestions for the user visible option, etc? > > > Well, I guess it's the equivalent of /MD /MT, i.e. is your CRT static or > dynamic. How is this expressed to GCC? I don't think they really have any equivalent; on mingw, the CRT itself can only be linked dynamically, and for things like libstdc++, it follows the `-static` flag (i.e. normally looks for libs named `libX.dll.a`, and if not found or if `-static` is specified, looks for `libX.a`). But `-static` is a linker flag only so it doesn't help for deciding what to emit at compile time. >> Actually, it feels like that blogpost is rather outdated; I can't manage to >> make current binutils produce this form of fixups for the issue at all. What >> it does however, is create a runtime pseudo relocation; the linker generates >> extra info in the rdata section about the relocations it wasn't able to >> handle, which the mingw crt will fix up on startup before handing control >> over to the end user code. This can involve changing the protection of the >> code sections to writeable in order to do such fixups there. (This feature >> has been in binutils since 2002.) > > So basically mingw has a custom relocation format layered on top of PE. I > mean, that would certainly help code size. Otherwise, every TU that emits a > vtable with RTTI is going to need a dynamic initializer... that would be bad > for startup time, unless we have clever ways to dedupe them across TUs. > > Maybe the cleaner thing to do is to actually handle this as a relocation. I > tried to figure out what GCC is doing, but it doesn't seem to work at all. This was my conclusion at some point as well - but there's also a few issues with that approach which makes me quite hesitant: - doing fixups in the code segment Repository: rC Clang https://reviews.llvm.org/D43184 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
