Revert "Merge pull request #7401 from swiftix/wip-generics-inlining-flag-4"

This reverts commit a380855, reversing
changes made to 6633214.

We're seeing a handful of issues from turning on inlining of generics,
so I'm reverting to unblock the bots.

Author: jrose-apple

lib/SIL/SILModule.cpp

@@ -499,14 +499,6 @@ bool SILModule::linkFunction(StringRef Name, SILModule::LinkingMode Mode) {
   return SILLinkerVisitor(*this, getSILLoader(), Mode).processFunction(Name);
 }
 
-bool SILModule::hasFunction(StringRef Name) {
-  if (lookUpFunction(Name))
-    return true;
-  SILLinkerVisitor Visitor(*this, getSILLoader(),
-                           SILModule::LinkingMode::LinkNormal);
-  return Visitor.hasFunction(Name);
-}
-
 /// Check if a given SIL linkage matches the required linkage.
 /// If the required linkage is Private, then anything matches it.
 static bool isMatchingLinkage(SILLinkage ActualLinkage,
@@ -516,15 +508,19 @@ static bool isMatchingLinkage(SILLinkage ActualLinkage,
   return ActualLinkage == Linkage;
 }
 
+bool SILModule::hasFunction(StringRef Name) {
+  if (lookUpFunction(Name))
+    return true;
+  SILLinkerVisitor Visitor(*this, getSILLoader(),
+                           SILModule::LinkingMode::LinkNormal);
+  return Visitor.hasFunction(Name);
+}
+
 SILFunction *SILModule::findFunction(StringRef Name,
                                      Optional<SILLinkage> Linkage) {
-  assert(Linkage);
-  auto RequiredLinkage = *Linkage;
-  assert((RequiredLinkage == SILLinkage::Public ||
-          RequiredLinkage == SILLinkage::PublicExternal) &&
-         "Only a lookup of public functions is supported currently");
 
   SILFunction *F = nullptr;
+  SILLinkage RequiredLinkage = Linkage ? *Linkage : SILLinkage::Private;
 
   // First, check if there is a function with a required name in the
   // current module.
@@ -569,20 +565,27 @@ SILFunction *SILModule::findFunction(StringRef Name,
     }
   }
 
-  // If an external public function representing a pre-specialization
-  // exists already and it is a non-optimizing compilation,
-  // simply convert it into an external declaration,
+  // If a function exists already and it is a non-optimizing
+  // compilation, simply convert it into an external declaration,
   // so that a compiled version from the shared library is used.
-  // It is important to remove its body here, because it may
-  // contain references to non-public functions.
   if (F->isDefinition() &&
       F->getModule().getOptions().Optimization <
           SILOptions::SILOptMode::Optimize) {
     F->convertToDeclaration();
   }
-  if (F->isExternalDeclaration())
+  if (F->isExternalDeclaration()) {
     F->setFragile(IsFragile_t::IsNotFragile);
-  F->setLinkage(RequiredLinkage);
+    if (isAvailableExternally(F->getLinkage()) &&
+        !hasPublicVisibility(F->getLinkage()) && !Linkage) {
+      // We were just asked if a given function exists anywhere.
+      // It is not going to be used by the current module.
+      // Since external non-public function declarations should not
+      // exist, strip the "external" part from the linkage.
+      F->setLinkage(stripExternalFromLinkage(F->getLinkage()));
+    }
+  }
+  if (Linkage)
+    F->setLinkage(RequiredLinkage);
   return F;
 }