Switch function signature optimization away from call graph.

Use the new function ordering utility instead.

Author: rudkx

lib/SILPasses/IPO/FunctionSignatureOpts.cpp

@@ -12,7 +12,8 @@
 
 #define DEBUG_TYPE "sil-function-signature-opts"
 #include "swift/SILPasses/Passes.h"
-#include "swift/SILAnalysis/CallGraphAnalysis.h"
+#include "swift/SILAnalysis/BasicCalleeAnalysis.h"
+#include "swift/SILAnalysis/FunctionOrder.h"
 #include "swift/SILAnalysis/RCIdentityAnalysis.h"
 #include "swift/SILAnalysis/ARCAnalysis.h"
 #include "swift/SILPasses/Transforms.h"
@@ -981,14 +982,12 @@ class FunctionSignatureOpts : public SILModuleTransform {
 
   void run() override {
     SILModule *M = getModule();
-    auto *CGA = getAnalysis<CallGraphAnalysis>();
+    auto *BCA = getAnalysis<BasicCalleeAnalysis>();
     auto *RCIA = getAnalysis<RCIdentityAnalysis>();
     llvm::BumpPtrAllocator Allocator;
 
     DEBUG(llvm::dbgs() << "**** Optimizing Function Signatures ****\n\n");
 
-    CallGraph &CG = CGA->getOrBuildCallGraph();
-
     // Construct a map from Callee -> Call Site Set.
 
     // Process each function in the callgraph that we are able to optimize.
@@ -1029,7 +1028,8 @@ class FunctionSignatureOpts : public SILModuleTransform {
       }
     }
 
-    for (auto *F : CG.getBottomUpFunctionOrder()) {
+    BottomUpFunctionOrder BottomUpOrder(*M, BCA);
+    for (auto *F : BottomUpOrder.getFunctions()) {
       // Don't optimize callees that should not be optimized.
       if (!F->shouldOptimize())
         continue;