Frontend: force order of evaluation #19346
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lib/Frontend/Frontend.cpp
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| Context->LoadedModules[MainModule->getName()] = getMainModule(); | ||
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| ModuleDecl *mainModule = getMainModule(); | ||
| Context->LoadedModules[MainModule->getName()] = mainModule; |
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Can you read the name from mainModule and not the instance variable here as well?
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Sure, I can do that, it is trivial enough. Shouldn't AA ensure that the extra load is elided? Or is there another purpose to the change?
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If getMainModule is inlined it probably would, but it still seems like a funny thing to rely on.
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It’s not a perf thing, it’s a code smell thing. It’s lazily initialized so all direct access to the instance variable can break the laziness contract - order of evaluation issues aside.
The previous statement happened to work out of sheer luck. `MainModule` is initialized by the call to `getMainModule()`. The expression could be evaluated in any order, and in the Visual Studio case, was evaluated with the index *first*. At this point `MainModule` was uninitialized (fortunately, it was set to NULL). As a result, the `getName` call would fail. Ensure that the `MainModule` is initialized first by using a local variable.
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The previous statement happened to work out of sheer luck.
MainModuleisinitialized by the call to
getMainModule(). The expression could be evaluatedin any order, and in the Visual Studio case, was evaluated with the index
first. At this point
MainModulewas uninitialized (fortunately, it was setto NULL). As a result, the
getNamecall would fail. Ensure that theMainModuleis initialized first by using a local variable.Replace this paragraph with a description of your changes and rationale. Provide links to external references/discussions if appropriate.
Resolves SR-NNNN.