Merge pull request swiftlang#30074 from eeckstein/globalopt

GlobalOpt: improvements for constant folding global variables

Author: eeckstein

include/swift/SIL/SILBuilder.h

@@ -197,6 +197,8 @@ class SILBuilder {
     assert(F && "cannot create this instruction without a function context");
     return *F;
   }
+  
+  bool isInsertingIntoGlobal() const { return F == nullptr; }
 
   TypeExpansionContext getTypeExpansionContext() const {
     return TypeExpansionContext(getFunction());

include/swift/SIL/SILCloner.h

@@ -149,7 +149,8 @@ class SILCloner : protected SILInstructionVisitor<ImplClass> {
   /// override the implementation via `postProcess`.
   void recordClonedInstruction(SILInstruction *Orig, SILInstruction *Cloned) {
     asImpl().postProcess(Orig, Cloned);
-    assert((Orig->getDebugScope() ? Cloned->getDebugScope() != nullptr : true)
+    assert((!Orig->getDebugScope() || Cloned->getDebugScope() ||
+            Builder.isInsertingIntoGlobal())
            && "cloned instruction dropped debug scope");
   }
 
@@ -560,7 +561,8 @@ template<typename ImplClass>
 void
 SILCloner<ImplClass>::postProcess(SILInstruction *orig,
                                   SILInstruction *cloned) {
-  assert((orig->getDebugScope() ? cloned->getDebugScope()!=nullptr : true) &&
+  assert((!orig->getDebugScope() || cloned->getDebugScope() ||
+          Builder.isInsertingIntoGlobal()) &&
          "cloned function dropped debug scope");
 
   // It sometimes happens that an instruction with no results gets mapped

include/swift/SILOptimizer/Utils/BasicBlockOptUtils.h

@@ -289,10 +289,18 @@ class StaticInitCloner : public SILCloner<StaticInitCloner> {
   /// don't have any operands).
   llvm::SmallVector<SILInstruction *, 8> readyToClone;
 
+  SILInstruction *insertionPoint = nullptr;
+
 public:
   StaticInitCloner(SILGlobalVariable *gVar)
       : SILCloner<StaticInitCloner>(gVar) {}
 
+  StaticInitCloner(SILInstruction *insertionPoint)
+      : SILCloner<StaticInitCloner>(*insertionPoint->getFunction()),
+        insertionPoint(insertionPoint) {
+    Builder.setInsertionPoint(insertionPoint);
+  }
+
   /// Add \p InitVal and all its operands (transitively) for cloning.
   ///
   /// Note: all init values must are added, before calling clone().
@@ -314,8 +322,16 @@ class StaticInitCloner : public SILCloner<StaticInitCloner> {
 
 protected:
   SILLocation remapLocation(SILLocation loc) {
+    if (insertionPoint)
+      return insertionPoint->getLoc();
     return ArtificialUnreachableLocation();
   }
+
+  const SILDebugScope *remapScope(const SILDebugScope *DS) {
+    if (insertionPoint)
+      return insertionPoint->getDebugScope();
+    return nullptr;
+  }
 };
 
 } // namespace swift