LTO: Verify the input even if optimize() isn't called

Clients may call writeMergedModules before calling optimize, or call
compileOptimized without calling optimize.  Make sure they don't sneak
past the verifier.  This adds LTOCodeGenerator::verifyMergedModuleOnce,
and calls it from writeMergedModule, optimize, and codegenOptimized.

I couldn't find a good way to test this.  I tried writing broken IR to
send into llvm-lto, but LTOCodeGenerator doesn't understand textual IR,
and assembler runs the verifier itself anyway.  Checking in
valid-but-doesn't-verify bitcode here doesn't seem valuable.

llvm-svn: 266894

include/llvm/LTO/LTOCodeGenerator.h

@@ -68,9 +68,13 @@ struct LTOCodeGenerator {
   ~LTOCodeGenerator();
 
   /// Merge given module.  Return true on success.
+  ///
+  /// Resets \a HasVerifiedInput.
   bool addModule(struct LTOModule *);
 
   /// Set the destination module.
+  ///
+  /// Resets \a HasVerifiedInput.
   void setModule(std::unique_ptr<LTOModule> M);
 
   void setTargetOptions(TargetOptions Options);
@@ -123,6 +127,8 @@ struct LTOCodeGenerator {
 
   /// Write the merged module to the file specified by the given path.  Return
   /// true on success.
+  ///
+  /// Calls \a verifyMergedModuleOnce().
   bool writeMergedModules(const char *Path);
 
   /// Compile the merged module into a *single* output file; the path to output
@@ -147,6 +153,8 @@ struct LTOCodeGenerator {
                                         bool DisableVectorization);
 
   /// Optimizes the merged module.  Returns true on success.
+  ///
+  /// Calls \a verifyMergedModuleOnce().
   bool optimize(bool DisableVerify, bool DisableInline, bool DisableGVNLoadPRE,
                 bool DisableVectorization);
 
@@ -160,6 +168,8 @@ struct LTOCodeGenerator {
   /// than one element, code generation is done in parallel with out.size()
   /// threads.  Output files will be written to members of out. Returns true on
   /// success.
+  ///
+  /// Calls \a verifyMergedModuleOnce().
   bool compileOptimized(ArrayRef<raw_pwrite_stream *> Out);
 
   void setDiagnosticHandler(lto_diagnostic_handler_t, void *);
@@ -171,6 +181,12 @@ struct LTOCodeGenerator {
 private:
   void initializeLTOPasses();
 
+  /// Verify the merged module on first call.
+  ///
+  /// Sets \a HasVerifiedInput on first call and doesn't run again on the same
+  /// input.
+  void verifyMergedModuleOnce();
+
   bool compileOptimizedToFile(const char **Name);
   void restoreLinkageForExternals();
   void applyScopeRestrictions();
@@ -189,6 +205,7 @@ private:
   std::unique_ptr<TargetMachine> TargetMach;
   bool EmitDwarfDebugInfo = false;
   bool ScopeRestrictionsDone = false;
+  bool HasVerifiedInput = false;
   Reloc::Model RelocModel = Reloc::Default;
   StringSet<> MustPreserveSymbols;
   StringSet<> AsmUndefinedRefs;

lib/LTO/LTOCodeGenerator.cpp

@@ -131,6 +131,9 @@ bool LTOCodeGenerator::addModule(LTOModule *Mod) {
   for (int i = 0, e = undefs.size(); i != e; ++i)
     AsmUndefinedRefs[undefs[i]] = 1;
 
+  // We've just changed the input, so let's make sure we verify it.
+  HasVerifiedInput = false;
+
   return !ret;
 }
 
@@ -146,6 +149,9 @@ void LTOCodeGenerator::setModule(std::unique_ptr<LTOModule> Mod) {
   const std::vector<const char*> &Undefs = Mod->getAsmUndefinedRefs();
   for (int I = 0, E = Undefs.size(); I != E; ++I)
     AsmUndefinedRefs[Undefs[I]] = 1;
+
+  // We've just changed the input, so let's make sure we verify it.
+  HasVerifiedInput = false;
 }
 
 void LTOCodeGenerator::setTargetOptions(TargetOptions Options) {
@@ -187,6 +193,9 @@ bool LTOCodeGenerator::writeMergedModules(const char *Path) {
   if (!determineTarget())
     return false;
 
+  // We always run the verifier once on the merged module.
+  verifyMergedModuleOnce();
+
   // mark which symbols can not be internalized
   applyScopeRestrictions();
 
@@ -413,6 +422,16 @@ void LTOCodeGenerator::restoreLinkageForExternals() {
                 externalize);
 }
 
+void LTOCodeGenerator::verifyMergedModuleOnce() {
+  // Only run on the first call.
+  if (HasVerifiedInput)
+    return;
+  HasVerifiedInput = true;
+
+  if (verifyModule(*MergedModule, &dbgs()))
+    report_fatal_error("Broken module found, compilation aborted!");
+}
+
 /// Optimize merged modules using various IPO passes
 bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
                                 bool DisableGVNLoadPRE,
@@ -422,8 +441,7 @@ bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
 
   // We always run the verifier once on the merged module, the `DisableVerify`
   // parameter only applies to subsequent verify.
-  if (verifyModule(*MergedModule, &dbgs()))
-    report_fatal_error("Broken module found, compilation aborted!");
+  verifyMergedModuleOnce();
 
   // Mark which symbols can not be internalized
   this->applyScopeRestrictions();
@@ -461,6 +479,10 @@ bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
   if (!this->determineTarget())
     return false;
 
+  // We always run the verifier once on the merged module.  If it has already
+  // been called in optimize(), this call will return early.
+  verifyMergedModuleOnce();
+
   legacy::PassManager preCodeGenPasses;
 
   // If the bitcode files contain ARC code and were compiled with optimization,