[PassManager] Process the function in a bottom-up order.

This commit changes the order in which we process the functions in the module
from module order to bottom-up order. Right now this change should not make any
noticeable difference, but soon we'll be able to make the inliner a function
pass and improve the caching of our inter-procedural analysis like side-effects
analysis.

Author: nadavrot

lib/SILPasses/PassManager/PassManager.cpp

@@ -19,6 +19,7 @@
 #include "swift/SILPasses/Transforms.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "swift/SILAnalysis/FunctionOrder.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/TimeValue.h"
@@ -160,21 +161,25 @@ SILPassManager::SILPassManager(SILModule *M, llvm::StringRef Stage) :
 bool SILPassManager::runFunctionPasses(PassList FuncTransforms) {
   const SILOptions &Options = getOptions();
 
-  for (auto &F : *Mod) {
-    if (F.empty())
+  BasicCalleeAnalysis *BCA = getAnalysis<BasicCalleeAnalysis>();
+  BottomUpFunctionOrder BottomUpOrder(*Mod, BCA);
+  auto BottomUpFunctions = BottomUpOrder.getFunctions();
+
+  for (auto *F : BottomUpFunctions) {
+    if (F->empty())
       continue;
 
     // Don't optimize functions that are marked with the opt.never attribute.
-    if (!F.shouldOptimize())
+    if (!F->shouldOptimize())
       continue;
 
-    CompletedPasses &completedPasses = CompletedPassesMap[&F];
+    CompletedPasses &completedPasses = CompletedPassesMap[F];
 
     for (auto SFT : FuncTransforms) {
       PrettyStackTraceSILFunctionTransform X(SFT);
       SFT->injectPassManager(this);
-      SFT->injectFunction(&F);
-      
+      SFT->injectFunction(F);
+
       // If nothing changed since the last run of this pass, we can skip this
       // pass.
       if (completedPasses.test((size_t)SFT->getPassKind()))
@@ -188,13 +193,13 @@ bool SILPassManager::runFunctionPasses(PassList FuncTransforms) {
       if (SILPrintPassName)
         llvm::dbgs() << "#" << NumPassesRun << " Stage: " << StageName
                      << " Pass: " << SFT->getName()
-                     << ", Function: " << F.getName() << "\n";
+                     << ", Function: " << F->getName() << "\n";
 
-      if (doPrintBefore(SFT, &F)) {
+      if (doPrintBefore(SFT, F)) {
         llvm::dbgs() << "*** SIL function before " << StageName << " "
                      << SFT->getName() << " (" << NumOptimizationIterations
                      << ") ***\n";
-        F.dump(Options.EmitVerboseSIL);
+        F->dump(Options.EmitVerboseSIL);
       }
 
       llvm::sys::TimeValue StartTime = llvm::sys::TimeValue::now();
@@ -205,17 +210,17 @@ bool SILPassManager::runFunctionPasses(PassList FuncTransforms) {
       if (SILPrintPassTime) {
         auto Delta = llvm::sys::TimeValue::now().nanoseconds() -
           StartTime.nanoseconds();
-        llvm::dbgs() << Delta << " (" << SFT->getName() << "," << F.getName()
+        llvm::dbgs() << Delta << " (" << SFT->getName() << "," << F->getName()
                      << ")\n";
       }
 
       // If this pass invalidated anything, print and verify.
-      if (doPrintAfter(SFT, &F,
+      if (doPrintAfter(SFT, F,
                        currentPassHasInvalidated && SILPrintAll)) {
         llvm::dbgs() << "*** SIL function after " << StageName << " "
                      << SFT->getName() << " (" << NumOptimizationIterations
                      << ") ***\n";
-        F.dump(Options.EmitVerboseSIL);
+        F->dump(Options.EmitVerboseSIL);
       }
 
       // Remember if this pass didn't change anything.
@@ -224,8 +229,8 @@ bool SILPassManager::runFunctionPasses(PassList FuncTransforms) {
 
       if (Options.VerifyAll &&
           (currentPassHasInvalidated || SILVerifyWithoutInvalidation)) {
-        F.verify();
-        verifyAnalyses(&F);
+        F->verify();
+        verifyAnalyses(F);
       }
 
       ++NumPassesRun;