[PATCH] D131646: [clang][dataflow] Restructure loops to call widen on back edges

[Eric Li via Phabricator via cfe-commits]

li.zhe.hua added inline comments.


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Comment at: clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp:180
+      assert(Block->pred_size() == 2);
+      BackEdge = Pred;
+    }
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ymandel wrote:
> Might it be worth simply returning the backedge when you find it? Or is the assertion (above) sufficiently important to keep it as is?
So, I couldn't prove to myself that a block couldn't have two backedge predecessors from staring at the CFG code, but it seems conceptually unlikely enough that I'm OK simplifying this.


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Comment at: clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp:275
+  )";
+  auto BlockStates = llvm::cantFail(runAnalysis<ConvergesOnWidenAnalysis>(
+      Code, [](ASTContext &C) { return ConvergesOnWidenAnalysis(C); }));
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ymandel wrote:
> Might a (googletest) assertion here be better than `llvm::cantFail`? I would think that this line is the crux of checking whether it converges or not.
Ah, yes. I hadn't thought to look for `llvm::Expected` matchers; good call.


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  https://reviews.llvm.org/D131646/new/

https://reviews.llvm.org/D131646