Hi Richard,
On Mar 28, 2014, at 2:45 PM, Richard Smith <[email protected]> wrote: > On Fri, Mar 28, 2014 at 1:12 PM, Ben Langmuir <[email protected]> wrote: > This patch allows multiple modules that have the same name to coexist in the > module cache. To differentiate between two modules with the same name, we > will consider the path the module map file that they are defined by* part of > the ‘key’ for looking up the precompiled module (pcm file). Specifically, > this patch renames the precompiled module (pcm) files from > > cache-path/<module hash>/Foo.pcm > > to > > cache-path/<module hash>/Foo-<hash of module map path>.pcm > > From a high level, I don't really see why we need a second hash here. > Shouldn't the -I options be included in the <module hash>? If I build the > same module with different -I flags, that should resolve to different .pcm > files, regardless of whether it makes the module name resolve to a different > module.map file. If we include the -I options in the module hash, we will explode the number of module compilations needed. The following should all be able to share a module ‘A’. clang -fmodules -I /path/to/A -I /path/to/B some_file.c clang -fmodules -I /path/to/A -I /path/to/C some_file2.c clang -fmodules -I /path/to/A -I /path/to/D some_file3.c > Are you trying to cope with the case where the -I path finds multiple > module.map files defining the same module (where it's basically chance which > one will get built and used)? I don't really feel like this is the right > solution to that problem either -- we should remove the 'luck' aspect and use > some sane mechanism to determine which module.map files are loaded, and in > what order. Nope - that is not being addressed. > > Is this addressing some other case? > See above. > > In addition, I’ve taught the ASTReader to re-resolve the names of imported > modules during module loading so that if the header search context changes > between when a module was originally built and when it is loaded we can > rebuild it if necessary. For example, if module A imports module B > > first time: > clang -I /path/to/A -I /path/to/B … > > second time: > clang -I /path/to/A -I /different/path/to/B … > > will now rebuild A as expected. > > > * in the case of inferred modules, we use the module map file that *allowed* > the inference, not the __inferred_module.map file, since the inferred file > path is the same for every inferred module. > > > Review comments on the patch itself: > > + /// the inferrence (e.g. contained 'module *') rather than the virtual > > Typo 'inference', 'Module *'. > > + /// For an explanaition of \p ModuleMap, see Module::ModuleMap. > > Typo 'explanation'. > > + // safe becuase the FileManager is shared between the compiler instances. > > Typo ‘because' Thanks for catching the embarrassing quantity of typos :) > > + // the inferred module. If this->ModuleMap is nullptr, then we are using > + // -emit-module directly, and we cannot have an inferred module. > > I don't understand what this comment is trying to say. If we're using > -emit-module, then we were given a module map on the command-line; should > that not be referred to by this->ModuleMap? (Also, why 'this->'?) How can a > top-level module be inferred? Is that a framework-specific thing? Hmm, I don’t recall why I didn’t just pass in the InputFile as the module map. I’ll do that. Yes, AFAIK only framework modules can be inferred at the top-level. > > + StringRef ModuleMap = this->ModuleMap ? this->ModuleMap->getName() : > InFile; > > Please pick a different variable name rather than shadowing a member of > '*this' here. Will do. > > + // Construct the name <ModuleName>-<hash of ModuleMapPath>.pcm which > should > + // be globally unique to this particular module. > + llvm::APInt Code(64, llvm::hash_value(ModuleMapPath)); > + SmallString<128> HashStr; > + Code.toStringUnsigned(HashStr); > > Use base 36, like the module hash. I could have sworn I did… must have got lost along the way. Will do.
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