[PM] Port the PostOrderFunctionAttrs pass to the new pass manager and

convert one test to use this.

This is a particularly significant milestone because it required
a working per-function AA framework which can be queried over each
function from within a CGSCC transform pass (and additionally a module
analysis to be accessible). This is essentially *the* point of the
entire pass manager rewrite. A CGSCC transform is able to query for
multiple different function's analysis results. It works. The whole
thing appears to actually work and accomplish the original goal. While
we were able to hack function attrs and basic-aa to "work" in the old
pass manager, this port doesn't use any of that, it directly leverages
the new fundamental functionality.

For this to work, the CGSCC framework also has to support SCC-based
behavior analysis, etc. The only part of the CGSCC pass infrastructure
not sorted out at this point are the updates in the face of inlining and
running function passes that mutate the call graph.

The changes are pretty boring and boiler-plate. Most of the work was
factored into more focused preperatory patches. But this is what wires
it all together.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261203 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/InitializePasses.h

@@ -231,7 +231,7 @@ void initializePostDomOnlyViewerPass(PassRegistry&);
 void initializePostDomPrinterPass(PassRegistry&);
 void initializePostDomViewerPass(PassRegistry&);
 void initializePostDominatorTreePass(PassRegistry&);
-void initializePostOrderFunctionAttrsPass(PassRegistry&);
+void initializePostOrderFunctionAttrsLegacyPassPass(PassRegistry&);
 void initializePostRASchedulerPass(PassRegistry&);
 void initializePostMachineSchedulerPass(PassRegistry&);
 void initializePrintFunctionPassWrapperPass(PassRegistry&);

include/llvm/LinkAllPasses.h

@@ -36,6 +36,7 @@
 #include "llvm/IR/Function.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/IPO/FunctionAttrs.h"
 #include "llvm/Transforms/Instrumentation.h"
 #include "llvm/Transforms/ObjCARC.h"
 #include "llvm/Transforms/Scalar.h"
@@ -159,7 +160,7 @@ namespace {
       (void) llvm::createPostDomTree();
       (void) llvm::createInstructionNamerPass();
       (void) llvm::createMetaRenamerPass();
-      (void) llvm::createPostOrderFunctionAttrsPass();
+      (void) llvm::createPostOrderFunctionAttrsLegacyPass();
       (void) llvm::createReversePostOrderFunctionAttrsPass();
       (void) llvm::createMergeFunctionsPass();
       std::string buf;

include/llvm/Transforms/IPO.h

@@ -187,15 +187,6 @@ ModulePass *createBlockExtractorPass();
 /// (prototypes) that are not used.
 ModulePass *createStripDeadPrototypesPass();
 
-//===----------------------------------------------------------------------===//
-/// createPostOrderFunctionAttrsPass - This pass walks SCCs of the call graph
-/// in post-order to deduce and propagate function attributes. It can discover
-/// functions that do not access memory, or only read memory, and give them the
-/// readnone/readonly attribute. It also discovers function arguments that are
-/// not captured by the function and marks them with the nocapture attribute.
-///
-Pass *createPostOrderFunctionAttrsPass();
-
 //===----------------------------------------------------------------------===//
 /// createReversePostOrderFunctionAttrsPass - This pass walks SCCs of the call
 /// graph in RPO to deduce and propagate function attributes. Currently it

include/llvm/Transforms/IPO/FunctionAttrs.h

@@ -0,0 +1,45 @@
+//===-- FunctionAttrs.h - Compute function attrs --------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// Provides passes for computing function attributes based on interprocedural
+/// analyses.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
+#define LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
+
+#include "llvm/Analysis/LazyCallGraph.h"
+#include "llvm/Analysis/CGSCCPassManager.h"
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+/// Computes function attributes in post-order over the call graph.
+///
+/// By operating in post-order, this pass computes precise attributes for
+/// called functions prior to processsing their callers. This "bottom-up"
+/// approach allows powerful interprocedural inference of function attributes
+/// like memory access patterns, etc. It can discover functions that do not
+/// access memory, or only read memory, and give them the readnone/readonly
+/// attribute. It also discovers function arguments that are not captured by
+/// the function and marks them with the nocapture attribute.
+class PostOrderFunctionAttrsPass {
+public:
+  static StringRef name() { return "PostOrderFunctionAttrsPass"; }
+
+  PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager *AM);
+};
+
+/// Create a legacy pass manager instance of a pass to compute function attrs
+/// in post-order.
+Pass *createPostOrderFunctionAttrsLegacyPass();
+
+}
+
+#endif // LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H

lib/LTO/LTOCodeGenerator.cpp

@@ -93,7 +93,7 @@ void LTOCodeGenerator::initializeLTOPasses() {
   initializeSROALegacyPassPass(R);
   initializeSROA_DTPass(R);
   initializeSROA_SSAUpPass(R);
-  initializePostOrderFunctionAttrsPass(R);
+  initializePostOrderFunctionAttrsLegacyPassPass(R);
   initializeReversePostOrderFunctionAttrsPass(R);
   initializeGlobalsAAWrapperPassPass(R);
   initializeLICMPass(R);

lib/Passes/PassBuilder.cpp

@@ -32,6 +32,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Transforms/IPO/ForceFunctionAttrs.h"
+#include "llvm/Transforms/IPO/FunctionAttrs.h"
 #include "llvm/Transforms/IPO/InferFunctionAttrs.h"
 #include "llvm/Transforms/IPO/StripDeadPrototypes.h"
 #include "llvm/Transforms/InstCombine/InstCombine.h"

lib/Passes/PassRegistry.def

@@ -47,6 +47,7 @@ CGSCC_ANALYSIS("no-op-cgscc", NoOpCGSCCAnalysis())
 #define CGSCC_PASS(NAME, CREATE_PASS)
 #endif
 CGSCC_PASS("invalidate<all>", InvalidateAllAnalysesPass())
+CGSCC_PASS("function-attrs", PostOrderFunctionAttrsPass())
 CGSCC_PASS("no-op-cgscc", NoOpCGSCCPass())
 #undef CGSCC_PASS
 

lib/Transforms/IPO/FunctionAttrs.cpp

@@ -13,6 +13,7 @@
 ///
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/IPO/FunctionAttrs.h"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/ADT/SCCIterator.h"
 #include "llvm/ADT/SetVector.h"
@@ -51,39 +52,6 @@ namespace {
 typedef SmallSetVector<Function *, 8> SCCNodeSet;
 }
 
-namespace {
-struct PostOrderFunctionAttrs : public CallGraphSCCPass {
-  static char ID; // Pass identification, replacement for typeid
-  PostOrderFunctionAttrs() : CallGraphSCCPass(ID) {
-    initializePostOrderFunctionAttrsPass(*PassRegistry::getPassRegistry());
-  }
-
-  bool runOnSCC(CallGraphSCC &SCC) override;
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.setPreservesCFG();
-    AU.addRequired<AssumptionCacheTracker>();
-    AU.addRequired<TargetLibraryInfoWrapperPass>();
-    addUsedAAAnalyses(AU);
-    CallGraphSCCPass::getAnalysisUsage(AU);
-  }
-
-private:
-  TargetLibraryInfo *TLI;
-};
-}
-
-char PostOrderFunctionAttrs::ID = 0;
-INITIALIZE_PASS_BEGIN(PostOrderFunctionAttrs, "functionattrs",
-                      "Deduce function attributes", false, false)
-INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
-INITIALIZE_PASS_END(PostOrderFunctionAttrs, "functionattrs",
-                    "Deduce function attributes", false, false)
-
-Pass *llvm::createPostOrderFunctionAttrsPass() { return new PostOrderFunctionAttrs(); }
-
 namespace {
 /// The three kinds of memory access relevant to 'readonly' and
 /// 'readnone' attributes.
@@ -1019,7 +987,102 @@ static bool addNoRecurseAttrs(const SCCNodeSet &SCCNodes) {
   return setDoesNotRecurse(*F);
 }
 
-bool PostOrderFunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
+PreservedAnalyses
+PostOrderFunctionAttrsPass::run(LazyCallGraph::SCC &C, CGSCCAnalysisManager *AM) {
+  Module &M = *C.begin()->getFunction().getParent();
+  const ModuleAnalysisManager &MAM =
+      AM->getResult<ModuleAnalysisManagerCGSCCProxy>(C).getManager();
+  FunctionAnalysisManager &FAM =
+      AM->getResult<FunctionAnalysisManagerCGSCCProxy>(C).getManager();
+
+  // FIXME: Need some way to make it more reasonable to assume that this is
+  // always cached.
+  TargetLibraryInfo &TLI = *MAM.getCachedResult<TargetLibraryAnalysis>(M);
+
+  // We pass a lambda into functions to wire them up to the analysis manager
+  // for getting function analyses.
+  auto AARGetter = [&](Function &F) -> AAResults & {
+    return FAM.getResult<AAManager>(F);
+  };
+
+  // Fill SCCNodes with the elements of the SCC. Also track whether there are
+  // any external or opt-none nodes that will prevent us from optimizing any
+  // part of the SCC.
+  SCCNodeSet SCCNodes;
+  bool HasUnknownCall = false;
+  for (LazyCallGraph::Node &N : C) {
+    Function &F = N.getFunction();
+    if (F.hasFnAttribute(Attribute::OptimizeNone)) {
+      // Treat any function we're trying not to optimize as if it were an
+      // indirect call and omit it from the node set used below.
+      HasUnknownCall = true;
+      continue;
+    }
+    // Track whether any functions in this SCC have an unknown call edge.
+    // Note: if this is ever a performance hit, we can common it with
+    // subsequent routines which also do scans over the instructions of the
+    // function.
+    if (!HasUnknownCall)
+      for (Instruction &I : instructions(F))
+        if (auto CS = CallSite(&I))
+          if (!CS.getCalledFunction()) {
+            HasUnknownCall = true;
+            break;
+          }
+
+    SCCNodes.insert(&F);
+  }
+
+  bool Changed = false;
+  Changed |= addReadAttrs(SCCNodes, AARGetter);
+  Changed |= addArgumentAttrs(SCCNodes);
+
+  // If we have no external nodes participating in the SCC, we can deduce some
+  // more precise attributes as well.
+  if (!HasUnknownCall) {
+    Changed |= addNoAliasAttrs(SCCNodes);
+    Changed |= addNonNullAttrs(SCCNodes, TLI);
+    Changed |= removeConvergentAttrs(SCCNodes);
+    Changed |= addNoRecurseAttrs(SCCNodes);
+  }
+
+  return Changed ? PreservedAnalyses::none() : PreservedAnalyses::all();
+}
+
+namespace {
+struct PostOrderFunctionAttrsLegacyPass : public CallGraphSCCPass {
+  static char ID; // Pass identification, replacement for typeid
+  PostOrderFunctionAttrsLegacyPass() : CallGraphSCCPass(ID) {
+    initializePostOrderFunctionAttrsLegacyPassPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnSCC(CallGraphSCC &SCC) override;
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    AU.addRequired<AssumptionCacheTracker>();
+    AU.addRequired<TargetLibraryInfoWrapperPass>();
+    addUsedAAAnalyses(AU);
+    CallGraphSCCPass::getAnalysisUsage(AU);
+  }
+
+private:
+  TargetLibraryInfo *TLI;
+};
+}
+
+char PostOrderFunctionAttrsLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(PostOrderFunctionAttrsLegacyPass, "functionattrs",
+                      "Deduce function attributes", false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_END(PostOrderFunctionAttrsLegacyPass, "functionattrs",
+                    "Deduce function attributes", false, false)
+
+Pass *llvm::createPostOrderFunctionAttrsLegacyPass() { return new PostOrderFunctionAttrsLegacyPass(); }
+
+bool PostOrderFunctionAttrsLegacyPass::runOnSCC(CallGraphSCC &SCC) {
   TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
   bool Changed = false;
 

lib/Transforms/IPO/IPO.cpp

@@ -18,6 +18,7 @@
 #include "llvm/InitializePasses.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/IPO/FunctionAttrs.h"
 
 using namespace llvm;
 
@@ -41,7 +42,7 @@ void llvm::initializeIPO(PassRegistry &Registry) {
   initializeLowerBitSetsPass(Registry);
   initializeMergeFunctionsPass(Registry);
   initializePartialInlinerPass(Registry);
-  initializePostOrderFunctionAttrsPass(Registry);
+  initializePostOrderFunctionAttrsLegacyPassPass(Registry);
   initializeReversePostOrderFunctionAttrsPass(Registry);
   initializePruneEHPass(Registry);
   initializeStripDeadPrototypesLegacyPassPass(Registry);
@@ -73,7 +74,7 @@ void LLVMAddDeadArgEliminationPass(LLVMPassManagerRef PM) {
 }
 
 void LLVMAddFunctionAttrsPass(LLVMPassManagerRef PM) {
-  unwrap(PM)->add(createPostOrderFunctionAttrsPass());
+  unwrap(PM)->add(createPostOrderFunctionAttrsLegacyPass());
 }
 
 void LLVMAddFunctionInliningPass(LLVMPassManagerRef PM) {

lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -31,6 +31,7 @@
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Transforms/IPO/ForceFunctionAttrs.h"
+#include "llvm/Transforms/IPO/FunctionAttrs.h"
 #include "llvm/Transforms/IPO/InferFunctionAttrs.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Vectorize.h"
@@ -382,7 +383,7 @@ void PassManagerBuilder::populateModulePassManager(
     Inliner = nullptr;
   }
   if (!DisableUnitAtATime)
-    MPM.add(createPostOrderFunctionAttrsPass());
+    MPM.add(createPostOrderFunctionAttrsLegacyPass());
   if (OptLevel > 2)
     MPM.add(createArgumentPromotionPass()); // Scalarize uninlined fn args
 
@@ -577,7 +578,7 @@ void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
   PM.add(createIPSCCPPass());
 
   // Now that we internalized some globals, see if we can hack on them!
-  PM.add(createPostOrderFunctionAttrsPass());
+  PM.add(createPostOrderFunctionAttrsLegacyPass());
   PM.add(createReversePostOrderFunctionAttrsPass());
   PM.add(createGlobalOptimizerPass());
   // Promote any localized global vars.
@@ -627,7 +628,7 @@ void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
     PM.add(createScalarReplAggregatesPass());
 
   // Run a few AA driven optimizations here and now, to cleanup the code.
-  PM.add(createPostOrderFunctionAttrsPass()); // Add nocapture.
+  PM.add(createPostOrderFunctionAttrsLegacyPass()); // Add nocapture.
   PM.add(createGlobalsAAWrapperPass()); // IP alias analysis.
 
   PM.add(createLICMPass());                 // Hoist loop invariants.

test/Transforms/FunctionAttrs/readattrs.ll

@@ -1,4 +1,5 @@
 ; RUN: opt < %s -functionattrs -S | FileCheck %s
+; RUN: opt < %s -aa-pipeline=basic-aa -passes='require<targetlibinfo>,cgscc(function-attrs)' -S | FileCheck %s
 @x = global i32 0
 
 declare void @test1_1(i8* %x1_1, i8* readonly %y1_1, ...)