[NFC][DwarfDebug] Add test for variables with a single location which

don't span their entire scope.

The previous commit (6d1c40c) is an older version of the test.

Reviewed By: aprantl, vsk

Differential Revision: https://reviews.llvm.org/D79573

llvm/include/llvm/Analysis/AssumeBundleQueries.h

@@ -122,6 +122,9 @@ inline RetainedKnowledge getKnowledgeFromUseInAssume(const Use *U) {
                                          U->getOperandNo());
 }
 
+/// Tag in operand bundle indicating that this bundle should be ignored.
+constexpr StringRef IgnoreBundleTag = "ignore";
+
 /// Return true iff the operand bundles of the provided llvm.assume doesn't
 /// contain any valuable information. This is true when:
 ///  - The operand bundle is empty
@@ -154,6 +157,11 @@ RetainedKnowledge getKnowledgeValidInContext(
     const Instruction *CtxI, const DominatorTree *DT = nullptr,
     AssumptionCache *AC = nullptr);
 
+/// This extracts the Knowledge from an element of an operand bundle.
+/// This is mostly for use in the assume builder.
+RetainedKnowledge getKnowledgeFromBundle(CallInst &Assume,
+                                         const CallBase::BundleOpInfo &BOI);
+
 } // namespace llvm
 
 #endif

llvm/include/llvm/IR/LLVMContext.h

@@ -31,6 +31,7 @@ class LLVMContextImpl;
 class Module;
 class OptPassGate;
 template <typename T> class SmallVectorImpl;
+template <typename T> class StringMapEntry;
 class SMDiagnostic;
 class StringRef;
 class Twine;
@@ -107,6 +108,10 @@ class LLVMContext {
   /// \see LLVMContext::getOperandBundleTagID
   void getOperandBundleTags(SmallVectorImpl<StringRef> &Result) const;
 
+  /// getOrInsertBundleTag - Returns the Tag to use for an operand bundle of
+  /// name TagName.
+  StringMapEntry<uint32_t> *getOrInsertBundleTag(StringRef TagName) const;
+
   /// getOperandBundleTagID - Maps a bundle tag to an integer ID.  Every bundle
   /// tag registered with an LLVMContext has an unique ID.
   uint32_t getOperandBundleTagID(StringRef Tag) const;

llvm/include/llvm/InitializePasses.h

@@ -71,6 +71,7 @@ void initializeAggressiveInstCombinerLegacyPassPass(PassRegistry&);
 void initializeAliasSetPrinterPass(PassRegistry&);
 void initializeAlignmentFromAssumptionsPass(PassRegistry&);
 void initializeAlwaysInlinerLegacyPassPass(PassRegistry&);
+void initializeAssumeSimplifyPassLegacyPassPass(PassRegistry &);
 void initializeOpenMPOptLegacyPassPass(PassRegistry &);
 void initializeArgPromotionPass(PassRegistry&);
 void initializeAssumptionCacheTrackerPass(PassRegistry&);

llvm/include/llvm/Transforms/Utils.h

@@ -147,6 +147,13 @@ FunctionPass *createUnifyLoopExitsPass();
 // into a natural loop.
 //
 FunctionPass *createFixIrreduciblePass();
-}
+
+//===----------------------------------------------------------------------===//
+//
+// AssumeSimplify - remove redundant assumes and merge assumes in the same
+// BasicBlock when possible.
+//
+FunctionPass *createAssumeSimplifyPass();
+} // namespace llvm
 
 #endif

llvm/include/llvm/Transforms/Utils/AssumeBundleBuilder.h

@@ -41,6 +41,14 @@ IntrinsicInst *buildAssumeFromInst(Instruction *I);
 void salvageKnowledge(Instruction *I, AssumptionCache *AC = nullptr,
                       DominatorTree *DT = nullptr);
 
+/// This pass attempts to minimize the number of assume without loosing any
+/// information.
+struct AssumeSimplifyPass : public PassInfoMixin<AssumeSimplifyPass> {
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+
+FunctionPass *createAssumeSimplifyPass();
+
 /// This pass will try to build an llvm.assume for every instruction in the
 /// function. Its main purpose is testing.
 struct AssumeBuilderPass : public PassInfoMixin<AssumeBuilderPass> {

llvm/lib/Analysis/AssumeBundleQueries.cpp

@@ -89,11 +89,13 @@ void llvm::fillMapFromAssume(CallInst &AssumeCI, RetainedKnowledgeMap &Result) {
   }
 }
 
-static RetainedKnowledge
-getKnowledgeFromBundle(CallInst &Assume, const CallBase::BundleOpInfo &BOI) {
+RetainedKnowledge
+llvm::getKnowledgeFromBundle(CallInst &Assume,
+                             const CallBase::BundleOpInfo &BOI) {
   RetainedKnowledge Result;
   Result.AttrKind = Attribute::getAttrKindFromName(BOI.Tag->getKey());
-  Result.WasOn = getValueFromBundleOpInfo(Assume, BOI, ABA_WasOn);
+  if (bundleHasArgument(BOI, ABA_WasOn))
+    Result.WasOn = getValueFromBundleOpInfo(Assume, BOI, ABA_WasOn);
   if (BOI.End - BOI.Begin > ABA_Argument)
     Result.ArgValue =
         cast<ConstantInt>(getValueFromBundleOpInfo(Assume, BOI, ABA_Argument))
@@ -116,7 +118,7 @@ bool llvm::isAssumeWithEmptyBundle(CallInst &CI) {
          "this function is intended to be used on llvm.assume");
   return none_of(Assume.bundle_op_infos(),
                  [](const CallBase::BundleOpInfo &BOI) {
-                   return BOI.Tag->getKey() != "ignore";
+                   return BOI.Tag->getKey() != IgnoreBundleTag;
                  });
 }
 

llvm/lib/Analysis/AssumptionCache.cpp

@@ -80,7 +80,7 @@ findAffectedValues(CallInst *CI,
 
   for (unsigned Idx = 0; Idx != CI->getNumOperandBundles(); Idx++) {
     if (CI->getOperandBundleAt(Idx).Inputs.size() > ABA_WasOn &&
-        CI->getOperandBundleAt(Idx).getTagName() != "ignore")
+        CI->getOperandBundleAt(Idx).getTagName() != IgnoreBundleTag)
       AddAffected(CI->getOperandBundleAt(Idx).Inputs[ABA_WasOn], Idx);
   }
 

llvm/lib/IR/LLVMContext.cpp

@@ -282,6 +282,11 @@ void LLVMContext::getOperandBundleTags(SmallVectorImpl<StringRef> &Tags) const {
   pImpl->getOperandBundleTags(Tags);
 }
 
+StringMapEntry<uint32_t> *
+LLVMContext::getOrInsertBundleTag(StringRef TagName) const {
+  return pImpl->getOrInsertBundleTag(TagName);
+}
+
 uint32_t LLVMContext::getOperandBundleTagID(StringRef Tag) const {
   return pImpl->getOperandBundleTagID(Tag);
 }

llvm/lib/Passes/PassBuilder.cpp

@@ -259,6 +259,7 @@ extern cl::opt<bool> EnableOrderFileInstrumentation;
 extern cl::opt<bool> FlattenedProfileUsed;
 
 extern cl::opt<AttributorRunOption> AttributorRun;
+extern cl::opt<bool> EnableKnowledgeRetention;
 
 const PassBuilder::OptimizationLevel PassBuilder::OptimizationLevel::O0 = {
     /*SpeedLevel*/ 0,
@@ -425,6 +426,8 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
 
   // Catch trivial redundancies
   FPM.addPass(EarlyCSEPass(true /* Enable mem-ssa. */));
+  if (EnableKnowledgeRetention)
+    FPM.addPass(AssumeSimplifyPass());
 
   // Hoisting of scalars and load expressions.
   if (Level.getSpeedupLevel() > 1) {

llvm/lib/Passes/PassRegistry.def

@@ -167,6 +167,7 @@ FUNCTION_PASS("adce", ADCEPass())
 FUNCTION_PASS("add-discriminators", AddDiscriminatorsPass())
 FUNCTION_PASS("aggressive-instcombine", AggressiveInstCombinePass())
 FUNCTION_PASS("assume-builder", AssumeBuilderPass())
+FUNCTION_PASS("assume-simplify", AssumeSimplifyPass())
 FUNCTION_PASS("alignment-from-assumptions", AlignmentFromAssumptionsPass())
 FUNCTION_PASS("bdce", BDCEPass())
 FUNCTION_PASS("bounds-checking", BoundsCheckingPass())

llvm/lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -165,6 +165,8 @@ cl::opt<AttributorRunOption> AttributorRun(
                clEnumValN(AttributorRunOption::NONE, "none",
                           "disable attributor runs")));
 
+extern cl::opt<bool> EnableKnowledgeRetention;
+
 PassManagerBuilder::PassManagerBuilder() {
     OptLevel = 2;
     SizeLevel = 0;
@@ -359,6 +361,8 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
   assert(OptLevel >= 1 && "Calling function optimizer with no optimization level!");
   MPM.add(createSROAPass());
   MPM.add(createEarlyCSEPass(true /* Enable mem-ssa. */)); // Catch trivial redundancies
+  if (EnableKnowledgeRetention)
+    MPM.add(createAssumeSimplifyPass());
 
   if (OptLevel > 1) {
     if (EnableGVNHoist)