[NewPM][Sancov] Make Sancov a Module Pass instead of 2 Passes

This patch merges the sancov module and funciton passes into one module pass.

The reason for this is because we ran into an out of memory error when
attempting to run asan fuzzer on some protobufs (pc.cc files). I traced the OOM
error to the destructor of SanitizerCoverage where we only call
appendTo[Compiler]Used which calls appendToUsedList. I'm not sure where precisely
in appendToUsedList causes the OOM, but I am able to confirm that it's calling
this function *repeatedly* that causes the OOM. (I hacked sancov a bit such that
I can still create and destroy a new sancov on every function run, but only call
appendToUsedList after all functions in the module have finished. This passes, but
when I make it such that appendToUsedList is called on every sancov destruction,
we hit OOM.)

I don't think the OOM is from just adding to the SmallSet and SmallVector inside
appendToUsedList since in either case for a given module, they'll have the same
max size. I suspect that when the existing llvm.compiler.used global is erased,
the memory behind it isn't freed. I could be wrong on this though.

This patch works around the OOM issue by just calling appendToUsedList at the
end of every module run instead of function run. The same amount of constants
still get added to llvm.compiler.used, abd we make the pass usage and logic
simpler by not having any inter-pass dependencies.

Differential Revision: https://reviews.llvm.org/D66988

llvm-svn: 370971

Author: PiJoules

clang/lib/CodeGen/BackendUtil.cpp

@@ -224,7 +224,6 @@ static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
   auto Opts = getSancovOptsFromCGOpts(CGOpts);
   PM.add(createModuleSanitizerCoverageLegacyPassPass(Opts));
-  PM.add(createSanitizerCoverageLegacyPassPass(Opts));
 }
 
 // Check if ASan should use GC-friendly instrumentation for globals.
@@ -1159,11 +1158,6 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
             [SancovOpts](ModulePassManager &MPM) {
               MPM.addPass(ModuleSanitizerCoveragePass(SancovOpts));
             });
-        PB.registerOptimizerLastEPCallback(
-            [SancovOpts](FunctionPassManager &FPM,
-                         PassBuilder::OptimizationLevel Level) {
-              FPM.addPass(SanitizerCoveragePass(SancovOpts));
-            });
       }
 
       // Register callbacks to schedule sanitizer passes at the appropriate part of
@@ -1249,8 +1243,6 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
           CodeGenOpts.SanitizeCoverageTraceCmp) {
         auto SancovOpts = getSancovOptsFromCGOpts(CodeGenOpts);
         MPM.addPass(ModuleSanitizerCoveragePass(SancovOpts));
-        MPM.addPass(createModuleToFunctionPassAdaptor(
-            SanitizerCoveragePass(SancovOpts)));
       }
 
       addSanitizersAtO0(MPM, TargetTriple, LangOpts, CodeGenOpts);

llvm/include/llvm/InitializePasses.h

@@ -364,8 +364,6 @@ void initializeSROALegacyPassPass(PassRegistry&);
 void initializeSafeStackLegacyPassPass(PassRegistry&);
 void initializeSafepointIRVerifierPass(PassRegistry&);
 void initializeSampleProfileLoaderLegacyPassPass(PassRegistry&);
-void initializeSanitizerCoverageFunctionCheckLegacyPassPass(PassRegistry &);
-void initializeSanitizerCoverageLegacyPassPass(PassRegistry &);
 void initializeModuleSanitizerCoverageLegacyPassPass(PassRegistry &);
 void initializeScalarEvolutionWrapperPassPass(PassRegistry&);
 void initializeScalarizeMaskedMemIntrinPass(PassRegistry&);

llvm/include/llvm/Transforms/Instrumentation/SanitizerCoverage.h

@@ -16,29 +16,16 @@
 #ifndef LLVM_TRANSFORMS_INSTRUMENTATION_SANITIZERCOVERAGE_H
 #define LLVM_TRANSFORMS_INSTRUMENTATION_SANITIZERCOVERAGE_H
 
-#include "llvm/IR/Function.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/Transforms/Instrumentation.h"
 
 namespace llvm {
 
-/// This is the SanitizerCoverage pass used in the new pass manager. The
-/// pass instruments functions for coverage.
-class SanitizerCoveragePass : public PassInfoMixin<SanitizerCoveragePass> {
-public:
-  explicit SanitizerCoveragePass(
-      SanitizerCoverageOptions Options = SanitizerCoverageOptions())
-      : Options(Options) {}
-  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
-
-private:
-  SanitizerCoverageOptions Options;
-};
-
-/// This is the ModuleSanitizerCoverage pass used in the new pass manager. This
-/// adds initialization calls to the module for trace PC guards and 8bit
-/// counters if they are requested.
+/// This is the ModuleSanitizerCoverage pass used in the new pass manager. The
+/// pass instruments functions for coverage, adds initialization calls to the
+/// module for trace PC guards and 8bit counters if they are requested, and
+/// appends globals to llvm.compiler.used.
 class ModuleSanitizerCoveragePass
     : public PassInfoMixin<ModuleSanitizerCoveragePass> {
 public:
@@ -52,8 +39,6 @@ class ModuleSanitizerCoveragePass
 };
 
 // Insert SanitizerCoverage instrumentation.
-FunctionPass *createSanitizerCoverageLegacyPassPass(
-    const SanitizerCoverageOptions &Options = SanitizerCoverageOptions());
 ModulePass *createModuleSanitizerCoverageLegacyPassPass(
     const SanitizerCoverageOptions &Options = SanitizerCoverageOptions());
 

llvm/lib/Passes/PassRegistry.def

@@ -246,7 +246,6 @@ FUNCTION_PASS("kasan", AddressSanitizerPass(true, false, false))
 FUNCTION_PASS("msan", MemorySanitizerPass({}))
 FUNCTION_PASS("kmsan", MemorySanitizerPass({0, false, /*Kernel=*/true}))
 FUNCTION_PASS("tsan", ThreadSanitizerPass())
-FUNCTION_PASS("sancov-func", SanitizerCoveragePass())
 #undef FUNCTION_PASS
 
 #ifndef FUNCTION_PASS_WITH_PARAMS

llvm/lib/Transforms/Instrumentation/Instrumentation.cpp

@@ -116,7 +116,7 @@ void llvm::initializeInstrumentation(PassRegistry &Registry) {
   initializeMemorySanitizerLegacyPassPass(Registry);
   initializeHWAddressSanitizerLegacyPassPass(Registry);
   initializeThreadSanitizerLegacyPassPass(Registry);
-  initializeSanitizerCoverageLegacyPassPass(Registry);
+  initializeModuleSanitizerCoverageLegacyPassPass(Registry);
   initializeDataFlowSanitizerPass(Registry);
 }