[PATCH] D15996: Avoid undefined behavior in LinkAllPasses.h

[Dimitry Andric via llvm-commits]

dim updated this revision to Diff 44652.
dim added a comment.

Two updates:

- Use a wrapper class around RegionPass, and call createPrinterPass on it. This ensures RegionPass.cpp is linked in.
- Use a raw_string_ostream to pass to functions requiring a raw_ostream, to avoid having to dereference yet another nullptr.


http://reviews.llvm.org/D15996

Files:
  include/llvm/LinkAllPasses.h

Index: include/llvm/LinkAllPasses.h
===================================================================
--- include/llvm/LinkAllPasses.h
+++ include/llvm/LinkAllPasses.h
@@ -160,9 +160,11 @@
       (void) llvm::createPostOrderFunctionAttrsPass();
       (void) llvm::createReversePostOrderFunctionAttrsPass();
       (void) llvm::createMergeFunctionsPass();
-      (void) llvm::createPrintModulePass(*(llvm::raw_ostream*)nullptr);
-      (void) llvm::createPrintFunctionPass(*(llvm::raw_ostream*)nullptr);
-      (void) llvm::createPrintBasicBlockPass(*(llvm::raw_ostream*)nullptr);
+      std::string buf;
+      llvm::raw_string_ostream os(buf);
+      (void) llvm::createPrintModulePass(os);
+      (void) llvm::createPrintFunctionPass(os);
+      (void) llvm::createPrintBasicBlockPass(os);
       (void) llvm::createModuleDebugInfoPrinterPass();
       (void) llvm::createPartialInliningPass();
       (void) llvm::createLintPass();
@@ -186,9 +188,14 @@
 
       (void)new llvm::IntervalPartition();
       (void)new llvm::ScalarEvolutionWrapperPass();
-      ((llvm::Function*)nullptr)->viewCFGOnly();
-      llvm::RGPassManager RGM;
-      ((llvm::RegionPass*)nullptr)->runOnRegion((llvm::Region*)nullptr, RGM);
+      llvm::Function::Create(nullptr, llvm::GlobalValue::ExternalLinkage)->viewCFGOnly();
+      struct BogusRegionPass : public llvm::RegionPass {
+        explicit BogusRegionPass(char c) : RegionPass(c) {}
+        bool runOnRegion(llvm::Region *R, llvm::RGPassManager &RGM) override {
+          return false;
+        }
+      } BRP(0);
+      (void) BRP.createPrinterPass(os, "");
       llvm::AliasSetTracker X(*(llvm::AliasAnalysis*)nullptr);
       X.add(nullptr, 0, llvm::AAMDNodes()); // for -print-alias-sets
       (void) llvm::AreStatisticsEnabled();


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