Switch TargetTransformInfo from an immutable analysis pass that requires

a TargetMachine to construct (and thus isn't always available), to an
analysis group that supports layered implementations much like
AliasAnalysis does. This is a pretty massive change, with a few parts
that I was unable to easily separate (sorry), so I'll walk through it.

The first step of this conversion was to make TargetTransformInfo an
analysis group, and to sink the nonce implementations in
ScalarTargetTransformInfo and VectorTargetTranformInfo into
a NoTargetTransformInfo pass. This allows other passes to add a hard
requirement on TTI, and assume they will always get at least on
implementation.

The TargetTransformInfo analysis group leverages the delegation chaining
trick that AliasAnalysis uses, where the base class for the analysis
group delegates to the previous analysis *pass*, allowing all but tho
NoFoo analysis passes to only implement the parts of the interfaces they
support. It also introduces a new trick where each pass in the group
retains a pointer to the top-most pass that has been initialized. This
allows passes to implement one API in terms of another API and benefit
when some other pass above them in the stack has more precise results
for the second API.

The second step of this conversion is to create a pass that implements
the TargetTransformInfo analysis using the target-independent
abstractions in the code generator. This replaces the
ScalarTargetTransformImpl and VectorTargetTransformImpl classes in
lib/Target with a single pass in lib/CodeGen called
BasicTargetTransformInfo. This class actually provides most of the TTI
functionality, basing it upon the TargetLowering abstraction and other
information in the target independent code generator.

The third step of the conversion adds support to all TargetMachines to
register custom analysis passes. This allows building those passes with
access to TargetLowering or other target-specific classes, and it also
allows each target to customize the set of analysis passes desired in
the pass manager. The baseline LLVMTargetMachine implements this
interface to add the BasicTTI pass to the pass manager, and all of the
tools that want to support target-aware TTI passes call this routine on
whatever target machine they end up with to add the appropriate passes.

The fourth step of the conversion created target-specific TTI analysis
passes for the X86 and ARM backends. These passes contain the custom
logic that was previously in their extensions of the
ScalarTargetTransformInfo and VectorTargetTransformInfo interfaces.
I separated them into their own file, as now all of the interface bits
are private and they just expose a function to create the pass itself.
Then I extended these target machines to set up a custom set of analysis
passes, first adding BasicTTI as a fallback, and then adding their
customized TTI implementations.

The fourth step required logic that was shared between the target
independent layer and the specific targets to move to a different
interface, as they no longer derive from each other. As a consequence,
a helper functions were added to TargetLowering representing the common
logic needed both in the target implementation and the codegen
implementation of the TTI pass. While technically this is the only
change that could have been committed separately, it would have been
a nightmare to extract.

The final step of the conversion was just to delete all the old
boilerplate. This got rid of the ScalarTargetTransformInfo and
VectorTargetTransformInfo classes, all of the support in all of the
targets for producing instances of them, and all of the support in the
tools for manually constructing a pass based around them.

Now that TTI is a relatively normal analysis group, two things become
straightforward. First, we can sink it into lib/Analysis which is a more
natural layer for it to live. Second, clients of this interface can
depend on it *always* being available which will simplify their code and
behavior. These (and other) simplifications will follow in subsequent
commits, this one is clearly big enough.

Finally, I'm very aware that much of the comments and documentation
needs to be updated. As soon as I had this working, and plausibly well
commented, I wanted to get it committed and in front of the build bots.
I'll be doing a few passes over documentation later if it sticks.

Commits to update DragonEgg and Clang will be made presently.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171681 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 142 insertions, 64 deletions

diff --git a/lib/Target/ARM/ARM.h b/lib/Target/ARM/ARM.h
index 1446bbbb8e..3e1329936a 100644
--- a/lib/Target/ARM/ARM.h
+++ b/lib/Target/ARM/ARM.h
@@ -44,6 +44,9 @@ FunctionPass *createMLxExpansionPass();
 FunctionPass *createThumb2ITBlockPass();
 FunctionPass *createThumb2SizeReductionPass();
 
+/// \brief Creates an X86-specific Target Transformation Info pass.
+ImmutablePass *createARMTargetTransformInfoPass(const ARMBaseTargetMachine *TM);
+
 void LowerARMMachineInstrToMCInst(const MachineInstr *MI, MCInst &OutMI,
                                   ARMAsmPrinter &AP);
 
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index dcdbd96276..5b3e31f0b1 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -10344,35 +10344,3 @@ bool ARMTargetLowering::getTgtMemIntrinsic(IntrinsicInfo &Info,
   return false;
 }
 
-unsigned
-ARMScalarTargetTransformImpl::getIntImmCost(const APInt &Imm, Type *Ty) const {
-  assert(Ty->isIntegerTy());
-
-  unsigned Bits = Ty->getPrimitiveSizeInBits();
-  if (Bits == 0 || Bits > 32)
-    return 4;
-
-  int32_t SImmVal = Imm.getSExtValue();
-  uint32_t ZImmVal = Imm.getZExtValue();
-  if (!Subtarget->isThumb()) {
-    if ((SImmVal >= 0 && SImmVal < 65536) ||
-        (ARM_AM::getSOImmVal(ZImmVal) != -1) ||
-        (ARM_AM::getSOImmVal(~ZImmVal) != -1))
-      return 1;
-    return Subtarget->hasV6T2Ops() ? 2 : 3;
-  } else if (Subtarget->isThumb2()) {
-    if ((SImmVal >= 0 && SImmVal < 65536) ||
-        (ARM_AM::getT2SOImmVal(ZImmVal) != -1) ||
-        (ARM_AM::getT2SOImmVal(~ZImmVal) != -1))
-      return 1;
-    return Subtarget->hasV6T2Ops() ? 2 : 3;
-  } else /*Thumb1*/ {
-    if (SImmVal >= 0 && SImmVal < 256)
-      return 1;
-    if ((~ZImmVal < 256) || ARM_AM::isThumbImmShiftedVal(ZImmVal))
-      return 2;
-    // Load from constantpool.
-    return 3;
-  }
-  return 2;
-}
diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index 61649a0d4d..9ee17f0781 100644
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -22,7 +22,6 @@
 #include "llvm/CodeGen/SelectionDAG.h"
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Target/TargetTransformImpl.h"
 #include <vector>
 
 namespace llvm {
@@ -574,16 +573,6 @@ namespace llvm {
     FastISel *createFastISel(FunctionLoweringInfo &funcInfo,
                              const TargetLibraryInfo *libInfo);
   }
-
-  class ARMScalarTargetTransformImpl : public ScalarTargetTransformImpl {
-    const ARMSubtarget *Subtarget;
-  public:
-    explicit ARMScalarTargetTransformImpl(const TargetLowering *TL) :
-      ScalarTargetTransformImpl(TL),
-      Subtarget(&TL->getTargetMachine().getSubtarget<ARMSubtarget>()) {};
-
-    virtual unsigned getIntImmCost(const APInt &Imm, Type *Ty) const;
-  };
 }
 
 #endif  // ARMISELLOWERING_H
diff --git a/lib/Target/ARM/ARMTargetMachine.cpp b/lib/Target/ARM/ARMTargetMachine.cpp
index 0613f2d939..dab7f178cd 100644
--- a/lib/Target/ARM/ARMTargetMachine.cpp
+++ b/lib/Target/ARM/ARMTargetMachine.cpp
@@ -51,6 +51,15 @@ ARMBaseTargetMachine::ARMBaseTargetMachine(const Target &T, StringRef TT,
     this->Options.FloatABIType = FloatABI::Soft;
 }
 
+void ARMBaseTargetMachine::addAnalysisPasses(PassManagerBase &PM) {
+  // Add first the target-independent BasicTTI pass, then our X86 pass. This
+  // allows the X86 pass to delegate to the target independent layer when
+  // appropriate.
+  PM.add(createBasicTargetTransformInfoPass(getTargetLowering()));
+  PM.add(createARMTargetTransformInfoPass(this));
+}
+
+
 void ARMTargetMachine::anchor() { }
 
 ARMTargetMachine::ARMTargetMachine(const Target &T, StringRef TT,
@@ -70,8 +79,7 @@ ARMTargetMachine::ARMTargetMachine(const Target &T, StringRef TT,
                            "v128:64:128-v64:64:64-n32-S32")),
     TLInfo(*this),
     TSInfo(*this),
-    FrameLowering(Subtarget),
-    STTI(&TLInfo), VTTI(&TLInfo) {
+    FrameLowering(Subtarget) {
   if (!Subtarget.hasARMOps())
     report_fatal_error("CPU: '" + Subtarget.getCPUString() + "' does not "
                        "support ARM mode execution!");
@@ -103,8 +111,7 @@ ThumbTargetMachine::ThumbTargetMachine(const Target &T, StringRef TT,
     TSInfo(*this),
     FrameLowering(Subtarget.hasThumb2()
               ? new ARMFrameLowering(Subtarget)
-              : (ARMFrameLowering*)new Thumb1FrameLowering(Subtarget)),
-    STTI(&TLInfo), VTTI(&TLInfo) {
+              : (ARMFrameLowering*)new Thumb1FrameLowering(Subtarget)) {
 }
 
 namespace {
diff --git a/lib/Target/ARM/ARMTargetMachine.h b/lib/Target/ARM/ARMTargetMachine.h
index bbc479501d..a8b21b2152 100644
--- a/lib/Target/ARM/ARMTargetMachine.h
+++ b/lib/Target/ARM/ARMTargetMachine.h
@@ -27,7 +27,6 @@
 #include "llvm/IR/DataLayout.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetTransformImpl.h"
 
 namespace llvm {
 
@@ -51,6 +50,9 @@ public:
     return &InstrItins;
   }
 
+  /// \brief Register X86 analysis passes with a pass manager.
+  virtual void addAnalysisPasses(PassManagerBase &PM);
+
   // Pass Pipeline Configuration
   virtual TargetPassConfig *createPassConfig(PassManagerBase &PM);
 
@@ -66,8 +68,6 @@ class ARMTargetMachine : public ARMBaseTargetMachine {
   ARMTargetLowering   TLInfo;
   ARMSelectionDAGInfo TSInfo;
   ARMFrameLowering    FrameLowering;
-  ARMScalarTargetTransformImpl STTI;
-  VectorTargetTransformImpl VTTI;
  public:
   ARMTargetMachine(const Target &T, StringRef TT,
                    StringRef CPU, StringRef FS,
@@ -89,12 +89,6 @@ class ARMTargetMachine : public ARMBaseTargetMachine {
   virtual const ARMFrameLowering *getFrameLowering() const {
     return &FrameLowering;
   }
-  virtual const ScalarTargetTransformInfo *getScalarTargetTransformInfo()const {
-    return &STTI;
-  }
-  virtual const VectorTargetTransformInfo *getVectorTargetTransformInfo()const {
-    return &VTTI;
-  }
   virtual const ARMInstrInfo     *getInstrInfo() const { return &InstrInfo; }
   virtual const DataLayout       *getDataLayout() const { return &DL; }
 };
@@ -112,8 +106,6 @@ class ThumbTargetMachine : public ARMBaseTargetMachine {
   ARMSelectionDAGInfo TSInfo;
   // Either Thumb1FrameLowering or ARMFrameLowering.
   OwningPtr<ARMFrameLowering> FrameLowering;
-  ARMScalarTargetTransformImpl STTI;
-  VectorTargetTransformImpl VTTI;
 public:
   ThumbTargetMachine(const Target &T, StringRef TT,
                      StringRef CPU, StringRef FS,
@@ -142,12 +134,6 @@ public:
   virtual const ARMFrameLowering *getFrameLowering() const {
     return FrameLowering.get();
   }
-  virtual const ScalarTargetTransformInfo *getScalarTargetTransformInfo()const {
-    return &STTI;
-  }
-  virtual const VectorTargetTransformInfo *getVectorTargetTransformInfo()const {
-    return &VTTI;
-  }
   virtual const DataLayout       *getDataLayout() const { return &DL; }
 };
 
diff --git a/lib/Target/ARM/ARMTargetTransformInfo.cpp b/lib/Target/ARM/ARMTargetTransformInfo.cpp
new file mode 100644
index 0000000000..7a830dd731
--- /dev/null
+++ b/lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -0,0 +1,124 @@
+//===-- ARMTargetTransformInfo.cpp - ARM specific TTI pass ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file implements a TargetTransformInfo analysis pass specific to the
+/// ARM target machine. It uses the target's detailed information to provide
+/// more precise answers to certain TTI queries, while letting the target
+/// independent and default TTI implementations handle the rest.
+///
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "armtti"
+#include "ARM.h"
+#include "ARMTargetMachine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/TargetTransformInfo.h"
+using namespace llvm;
+
+// Declare the pass initialization routine locally as target-specific passes
+// don't havve a target-wide initialization entry point, and so we rely on the
+// pass constructor initialization.
+namespace llvm {
+void initializeARMTTIPass(PassRegistry &);
+}
+
+namespace {
+
+class ARMTTI : public ImmutablePass, public TargetTransformInfo {
+  const ARMBaseTargetMachine *TM;
+  const ARMSubtarget *ST;
+
+  /// Estimate the overhead of scalarizing an instruction. Insert and Extract
+  /// are set if the result needs to be inserted and/or extracted from vectors.
+  unsigned getScalarizationOverhead(Type *Ty, bool Insert, bool Extract) const;
+
+public:
+  ARMTTI() : ImmutablePass(ID), TM(0), ST(0) {
+    llvm_unreachable("This pass cannot be directly constructed");
+  }
+
+  ARMTTI(const ARMBaseTargetMachine *TM)
+      : ImmutablePass(ID), TM(TM), ST(TM->getSubtargetImpl()) {
+    initializeARMTTIPass(*PassRegistry::getPassRegistry());
+  }
+
+  virtual void initializePass() {
+    pushTTIStack(this);
+  }
+
+  virtual void finalizePass() {
+    popTTIStack();
+  }
+
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+    TargetTransformInfo::getAnalysisUsage(AU);
+  }
+
+  /// Pass identification.
+  static char ID;
+
+  /// Provide necessary pointer adjustments for the two base classes.
+  virtual void *getAdjustedAnalysisPointer(const void *ID) {
+    if (ID == &TargetTransformInfo::ID)
+      return (TargetTransformInfo*)this;
+    return this;
+  }
+
+  /// \name Scalar TTI Implementations
+  /// @{
+
+  virtual unsigned getIntImmCost(const APInt &Imm, Type *Ty) const;
+
+  /// @}
+};
+
+} // end anonymous namespace
+
+INITIALIZE_AG_PASS(ARMTTI, TargetTransformInfo, "armtti",
+                   "ARM Target Transform Info", true, true, false)
+char ARMTTI::ID = 0;
+
+ImmutablePass *
+llvm::createARMTargetTransformInfoPass(const ARMBaseTargetMachine *TM) {
+  return new ARMTTI(TM);
+}
+
+
+unsigned ARMTTI::getIntImmCost(const APInt &Imm, Type *Ty) const {
+  assert(Ty->isIntegerTy());
+
+  unsigned Bits = Ty->getPrimitiveSizeInBits();
+  if (Bits == 0 || Bits > 32)
+    return 4;
+
+  int32_t SImmVal = Imm.getSExtValue();
+  uint32_t ZImmVal = Imm.getZExtValue();
+  if (!ST->isThumb()) {
+    if ((SImmVal >= 0 && SImmVal < 65536) ||
+        (ARM_AM::getSOImmVal(ZImmVal) != -1) ||
+        (ARM_AM::getSOImmVal(~ZImmVal) != -1))
+      return 1;
+    return ST->hasV6T2Ops() ? 2 : 3;
+  } else if (ST->isThumb2()) {
+    if ((SImmVal >= 0 && SImmVal < 65536) ||
+        (ARM_AM::getT2SOImmVal(ZImmVal) != -1) ||
+        (ARM_AM::getT2SOImmVal(~ZImmVal) != -1))
+      return 1;
+    return ST->hasV6T2Ops() ? 2 : 3;
+  } else /*Thumb1*/ {
+    if (SImmVal >= 0 && SImmVal < 256)
+      return 1;
+    if ((~ZImmVal < 256) || ARM_AM::isThumbImmShiftedVal(ZImmVal))
+      return 2;
+    // Load from constantpool.
+    return 3;
+  }
+  return 2;
+}
diff --git a/lib/Target/ARM/CMakeLists.txt b/lib/Target/ARM/CMakeLists.txt
index e279e2d829..586834cf73 100644
--- a/lib/Target/ARM/CMakeLists.txt
+++ b/lib/Target/ARM/CMakeLists.txt
@@ -37,6 +37,7 @@ add_llvm_target(ARMCodeGen
   ARMSubtarget.cpp
   ARMTargetMachine.cpp
   ARMTargetObjectFile.cpp
+  ARMTargetTransformInfo.cpp
   MLxExpansionPass.cpp
   Thumb1FrameLowering.cpp
   Thumb1InstrInfo.cpp