Merge pull request swiftlang#1847 from trentxintong/FSO

Make FSO thunks always_inline.

Author: trentxintong

lib/SILOptimizer/Analysis/FunctionSignatureAnalysis.cpp

@@ -252,8 +252,6 @@ std::string FunctionSignatureInfo::getOptimizedName() const {
   auto P = SpecializationPass::FunctionSignatureOpts;
   FunctionSignatureSpecializationMangler FSSM(P, M, F);
 
-  std::string ArgEnc;
-
   // Handle arguments' changes.
   for (unsigned i : indices(ArgDescList)) {
     const ArgumentDescriptor &Arg = ArgDescList[i];
@@ -271,9 +269,6 @@ std::string FunctionSignatureInfo::getOptimizedName() const {
     // mangling.
     if (Arg.Explode && !Arg.IsEntirelyDead) {
       FSSM.setArgumentSROA(i);
-      // Generate a string of encoding for the argument projection tree.
-      // TODO: we can put this into the mangler itself.
-      ArgEnc += "_arg" + std::to_string(i) + "_" + Arg.ProjTree.getNameEncoding();
     }
   }
 
@@ -285,7 +280,7 @@ std::string FunctionSignatureInfo::getOptimizedName() const {
 
   FSSM.mangle();
 
-  return M.finalize() + ArgEnc;
+  return M.finalize();
 }
 
 

lib/SILOptimizer/PassManager/Passes.cpp

@@ -340,11 +340,6 @@ void swift::runSILOptimizationPasses(SILModule &Module) {
 
   PM.setStageName("LowLevel");
 
-  // Rewrite to get the benefit of release devirtualizer.
-  // Also, Make sure the run the rewriter to create the optimized functions before
-  // the cloner on the current function is run !.
-  PM.addFunctionSignatureOptRewriter();
-
   // Should be after FunctionSignatureOpts and before the last inliner.
   PM.addReleaseDevirtualizer();
 

lib/SILOptimizer/Transforms/FunctionSignatureOptCloner.cpp

@@ -566,7 +566,13 @@ class FunctionSignatureOptCloner : public SILFunctionTransform {
                  createOptimizedFunction(RCIA->get(F), FSA->get(F), AA, F);
 
     if (NewF) { 
-      // Make sure the PM knows about this function.
+      // The thunk now carries the information on how the signature is
+      // optimized. If we inline the thunk, we will get the benefit of calling
+      // the signature optimized function without additional setup on the
+      // caller side.
+      F->setInlineStrategy(AlwaysInline);
+      // Make sure the PM knows about this function. This will also help us
+      // with self-recursion.
       notifyPassManagerOfFunction(NewF);
       invalidateAnalysis(SILAnalysis::InvalidationKind::Everything);
     }

test/SILOptimizer/devirt_default_case.swift

@@ -109,7 +109,7 @@ func foo(a: A3) -> Int {
 // Check that call to A3.f() can be devirtualized.
 //
 // CHECK-NORMAL: sil{{( hidden)?}} [noinline] @_TF19devirt_default_case3fooFCS_2A3Si
-// CHECK-TESTABLE: sil{{( hidden)?}} [thunk] [noinline] @_TF19devirt_default_case3fooFCS_2A3Si
+// CHECK-TESTABLE: sil{{( hidden)?}} [thunk] [always_inline] @_TF19devirt_default_case3fooFCS_2A3Si
 // CHECK-NORMAL: function_ref @{{.*}}TFC19devirt_default_case2B31f
 // CHECK-NORMAL: function_ref @{{.*}}TFC19devirt_default_case2A31f
 // CHECK-NORMAL-NOT: class_method