[PM] Port instcombine to the new pass manager!

This is exciting as this is a much more involved port. This is
a complex, existing transformation pass. All of the core logic is shared
between both old and new pass managers. Only the access to the analyses
is separate because the actual techniques are separate. This also uses
a bunch of different and interesting analyses and is the first time
where we need to use an analysis across an IR layer.

This also paves the way to expose instcombine utility functions. I've
got a static function that implements the core pass logic over
a function which might be mildly interesting, but more interesting is
likely exposing a routine which just uses instructions *already in* the
worklist and combines until empty.

I've switched one of my favorite instcombine tests to run with both as
well to make sure this keeps working.

llvm-svn: 226987

1 files changed, 64 insertions, 35 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index d27801b85b5..9a42d4580b8 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -33,7 +33,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/InstCombine/InstCombine.h"
 #include "InstCombineInternal.h"
 #include "llvm-c/Initialization.h"
 #include "llvm/ADT/SmallPtrSet.h"
@@ -45,6 +45,7 @@
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/DataLayout.h"
@@ -55,7 +56,7 @@
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
-#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include <algorithm>
 #include <climits>
@@ -2922,6 +2923,66 @@ static bool prepareICWorklistFromFunction(Function &F, const DataLayout *DL,
   return MadeIRChange;
 }
 
+static bool combineInstructionsOverFunction(
+    Function &F, InstCombineWorklist &Worklist, AssumptionCache &AC,
+    TargetLibraryInfo &TLI, DominatorTree &DT, const DataLayout *DL = nullptr,
+    LoopInfo *LI = nullptr) {
+  // Minimizing size?
+  bool MinimizeSize = F.getAttributes().hasAttribute(
+      AttributeSet::FunctionIndex, Attribute::MinSize);
+
+  /// Builder - This is an IRBuilder that automatically inserts new
+  /// instructions into the worklist when they are created.
+  IRBuilder<true, TargetFolder, InstCombineIRInserter> Builder(
+      F.getContext(), TargetFolder(DL), InstCombineIRInserter(Worklist, &AC));
+
+  // Lower dbg.declare intrinsics otherwise their value may be clobbered
+  // by instcombiner.
+  bool DbgDeclaresChanged = LowerDbgDeclare(F);
+
+  // Iterate while there is work to do.
+  int Iteration = 0;
+  for (;;) {
+    ++Iteration;
+    DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
+                 << F.getName() << "\n");
+
+    bool Changed = false;
+    if (prepareICWorklistFromFunction(F, DL, &TLI, Worklist))
+      Changed = true;
+
+    InstCombiner IC(Worklist, &Builder, MinimizeSize, &AC, &TLI, &DT, DL, LI);
+    if (IC.run())
+      Changed = true;
+
+    if (!Changed)
+      break;
+  }
+
+  return DbgDeclaresChanged || Iteration > 1;
+}
+
+PreservedAnalyses InstCombinePass::run(Function &F,
+                                       AnalysisManager<Function> *AM) {
+  auto *DL = F.getParent()->getDataLayout();
+
+  auto &AC = AM->getResult<AssumptionAnalysis>(F);
+  auto &DT = AM->getResult<DominatorTreeAnalysis>(F);
+  auto &TLI = AM->getResult<TargetLibraryAnalysis>(F);
+
+  auto *LI = AM->getCachedResult<LoopAnalysis>(F);
+
+  if (!combineInstructionsOverFunction(F, Worklist, AC, TLI, DT, DL, LI))
+    // No changes, all analyses are preserved.
+    return PreservedAnalyses::all();
+
+  // Mark all the analyses that instcombine updates as preserved.
+  // FIXME: Need a way to preserve CFG analyses here!
+  PreservedAnalyses PA;
+  PA.preserve<DominatorTreeAnalysis>();
+  return PA;
+}
+
 namespace {
 /// \brief The legacy pass manager's instcombine pass.
 ///
@@ -2954,10 +3015,6 @@ bool InstructionCombiningPass::runOnFunction(Function &F) {
   if (skipOptnoneFunction(F))
     return false;
 
-  // Lower dbg.declare intrinsics otherwise their value may be clobbered
-  // by instcombiner.
-  bool DbgDeclaresChanged = LowerDbgDeclare(F);
-
   // Required analyses.
   auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
   auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
@@ -2969,35 +3026,7 @@ bool InstructionCombiningPass::runOnFunction(Function &F) {
   auto *LIWP = getAnalysisIfAvailable<LoopInfoWrapperPass>();
   auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
 
-  // Minimizing size?
-  bool MinimizeSize = F.getAttributes().hasAttribute(
-      AttributeSet::FunctionIndex, Attribute::MinSize);
-
-  /// Builder - This is an IRBuilder that automatically inserts new
-  /// instructions into the worklist when they are created.
-  IRBuilder<true, TargetFolder, InstCombineIRInserter> Builder(
-      F.getContext(), TargetFolder(DL), InstCombineIRInserter(Worklist, &AC));
-
-  // Iterate while there is work to do.
-  int Iteration = 0;
-  for (;;) {
-    ++Iteration;
-    DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
-                 << F.getName() << "\n");
-
-    bool Changed = false;
-    if (prepareICWorklistFromFunction(F, DL, &TLI, Worklist))
-      Changed = true;
-
-    InstCombiner IC(Worklist, &Builder, MinimizeSize, &AC, &TLI, &DT, DL, LI);
-    if (IC.run())
-      Changed = true;
-
-    if (!Changed)
-      break;
-  }
-
-  return DbgDeclaresChanged || Iteration > 1;
+  return combineInstructionsOverFunction(F, Worklist, AC, TLI, DT, DL, LI);
 }
 
 char InstructionCombiningPass::ID = 0;