Rewrite the global merge pass to be subprogram agnostic for now.

It was previously using the subtarget to get values for the global
offset without actually checking each function as it was generating
code. Go ahead and solidify the current behavior and make the
existing FIXMEs more prominent.

As a note the ARM backend previously had a thumb1 and non-thumb1
set of defaults. Only the former was tested so I've changed the
behavior to only use that for now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230245 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h
index cd499ba5cb0f9855042b462c914df7ee94cfee72..d5ff0584422082d78d96fa403746651fee45404f 100644 (file)
--- a/include/llvm/Target/TargetLowering.h
+++ b/include/llvm/Target/TargetLowering.h
@@ -959,12 +959,6 @@ public:
     return false;
   }
 
-  /// Returns the maximal possible offset which can be used for loads / stores
-  /// from the global.
-  virtual unsigned getMaximalGlobalOffset() const {
-    return 0;
-  }
-
   /// Returns true if a cast between SrcAS and DestAS is a noop.
   virtual bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const {
     return false;

diff --git a/include/llvm/Transforms/Scalar.h b/include/llvm/Transforms/Scalar.h
index 108201f072fa49340444b10f60f2d9a64857c9ef..558b81e023c993d52f9ef1c205cdceb55b968ef6 100644 (file)
--- a/include/llvm/Transforms/Scalar.h
+++ b/include/llvm/Transforms/Scalar.h
@@ -145,7 +145,7 @@ Pass *createLICMPass();
 //
 Pass *createLoopStrengthReducePass();
 
-Pass *createGlobalMergePass(const TargetMachine *TM = nullptr);
+Pass *createGlobalMergePass(const TargetMachine *TM, unsigned MaximalOffset);
 
 //===----------------------------------------------------------------------===//
 //

diff --git a/lib/CodeGen/GlobalMerge.cpp b/lib/CodeGen/GlobalMerge.cpp
index 6da9766379e9bd699eea3048744dc01a7b57244e..32543b7723abe3b862f9e15a1f917ce6b5937987 100644 (file)
--- a/lib/CodeGen/GlobalMerge.cpp
+++ b/lib/CodeGen/GlobalMerge.cpp
@@ -90,10 +90,16 @@ EnableGlobalMergeOnExternal("global-merge-on-external", cl::Hidden,
      cl::desc("Enable global merge pass on external linkage"),
      cl::init(false));
 
-STATISTIC(NumMerged      , "Number of globals merged");
+STATISTIC(NumMerged, "Number of globals merged");
 namespace {
   class GlobalMerge : public FunctionPass {
     const TargetMachine *TM;
+    const DataLayout *DL;
+    // FIXME: Infer the maximum possible offset depending on the actual users
+    // (these max offsets are different for the users inside Thumb or ARM
+    // functions), see the code that passes in the offset in the ARM backend
+    // for more information.
+    unsigned MaxOffset;
 
     bool doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
                  Module &M, bool isConst, unsigned AddrSpace) const;
@@ -117,8 +123,10 @@ namespace {
 
   public:
     static char ID;             // Pass identification, replacement for typeid.
-    explicit GlobalMerge(const TargetMachine *TM = nullptr)
-      : FunctionPass(ID), TM(TM) {
+    explicit GlobalMerge(const TargetMachine *TM = nullptr,
+                         unsigned MaximalOffset = 0)
+        : FunctionPass(ID), TM(TM), DL(TM->getDataLayout()),
+          MaxOffset(MaximalOffset) {
       initializeGlobalMergePass(*PassRegistry::getPassRegistry());
     }
 
@@ -138,22 +146,16 @@ namespace {
 } // end anonymous namespace
 
 char GlobalMerge::ID = 0;
-INITIALIZE_TM_PASS(GlobalMerge, "global-merge", "Merge global variables",
-                   false, false)
+INITIALIZE_PASS_BEGIN(GlobalMerge, "global-merge", "Merge global variables",
+                      false, false)
+INITIALIZE_PASS_END(GlobalMerge, "global-merge", "Merge global variables",
+                    false, false)
 
 bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
                           Module &M, bool isConst, unsigned AddrSpace) const {
-  const TargetLowering *TLI = TM->getSubtargetImpl()->getTargetLowering();
-  const DataLayout *DL = TM->getDataLayout();
-
-  // FIXME: Infer the maximum possible offset depending on the actual users
-  // (these max offsets are different for the users inside Thumb or ARM
-  // functions)
-  unsigned MaxOffset = TLI->getMaximalGlobalOffset();
-
   // FIXME: Find better heuristics
   std::stable_sort(Globals.begin(), Globals.end(),
-                   [DL](const GlobalVariable *GV1, const GlobalVariable *GV2) {
+                   [this](const GlobalVariable *GV1, const GlobalVariable *GV2) {
     Type *Ty1 = cast<PointerType>(GV1->getType())->getElementType();
     Type *Ty2 = cast<PointerType>(GV2->getType())->getElementType();
 
@@ -282,9 +284,6 @@ bool GlobalMerge::doInitialization(Module &M) {
 
   DenseMap<unsigned, SmallVector<GlobalVariable*, 16> > Globals, ConstGlobals,
                                                         BSSGlobals;
-  const TargetLowering *TLI = TM->getSubtargetImpl()->getTargetLowering();
-  const DataLayout *DL = TM->getDataLayout();
-  unsigned MaxOffset = TLI->getMaximalGlobalOffset();
   bool Changed = false;
   setMustKeepGlobalVariables(M);
 
@@ -357,6 +356,6 @@ bool GlobalMerge::doFinalization(Module &M) {
   return false;
 }
 
-Pass *llvm::createGlobalMergePass(const TargetMachine *TM) {
-  return new GlobalMerge(TM);
+Pass *llvm::createGlobalMergePass(const TargetMachine *TM, unsigned Offset) {
+  return new GlobalMerge(TM, Offset);
 }

diff --git a/lib/Target/AArch64/AArch64ISelLowering.cpp b/lib/Target/AArch64/AArch64ISelLowering.cpp
index fb31d7d33763c46fb35920fdca773ce7db980567..f16ec9d00627a8331929eb3f6d0e29f6598862c7 100644 (file)
--- a/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -730,13 +730,6 @@ MVT AArch64TargetLowering::getScalarShiftAmountTy(EVT LHSTy) const {
   return MVT::i64;
 }
 
-unsigned AArch64TargetLowering::getMaximalGlobalOffset() const {
-  // FIXME: On AArch64, this depends on the type.
-  // Basically, the addressable offsets are up to 4095 * Ty.getSizeInBytes().
-  // and the offset has to be a multiple of the related size in bytes.
-  return 4095;
-}
-
 FastISel *
 AArch64TargetLowering::createFastISel(FunctionLoweringInfo &funcInfo,
                                       const TargetLibraryInfo *libInfo) const {

diff --git a/lib/Target/AArch64/AArch64ISelLowering.h b/lib/Target/AArch64/AArch64ISelLowering.h
index db15538e43be6959fb868188ad3c957a9cbea989..0a84294948fe1a3283dab37ccd0793876a0ea124 100644 (file)
--- a/lib/Target/AArch64/AArch64ISelLowering.h
+++ b/lib/Target/AArch64/AArch64ISelLowering.h
@@ -246,10 +246,6 @@ public:
   /// getFunctionAlignment - Return the Log2 alignment of this function.
   unsigned getFunctionAlignment(const Function *F) const;
 
-  /// getMaximalGlobalOffset - Returns the maximal possible offset which can
-  /// be used for loads / stores from the global.
-  unsigned getMaximalGlobalOffset() const override;
-
   /// Returns true if a cast between SrcAS and DestAS is a noop.
   bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const override {
     // Addrspacecasts are always noops.

diff --git a/lib/Target/AArch64/AArch64TargetMachine.cpp b/lib/Target/AArch64/AArch64TargetMachine.cpp
index 53360428050e7f79000d0669e43e976b4c357eb3..d73d0b3f8b709473f2bd8d8e08ef4e5175710417 100644 (file)
--- a/lib/Target/AArch64/AArch64TargetMachine.cpp
+++ b/lib/Target/AArch64/AArch64TargetMachine.cpp
@@ -236,8 +236,11 @@ bool AArch64PassConfig::addPreISel() {
   // get a chance to be merged
   if (TM->getOptLevel() != CodeGenOpt::None && EnablePromoteConstant)
     addPass(createAArch64PromoteConstantPass());
+  // FIXME: On AArch64, this depends on the type.
+  // Basically, the addressable offsets are up to 4095 * Ty.getSizeInBytes().
+  // and the offset has to be a multiple of the related size in bytes.
   if (TM->getOptLevel() != CodeGenOpt::None)
-    addPass(createGlobalMergePass(TM));
+    addPass(createGlobalMergePass(TM, 4095));
   if (TM->getOptLevel() != CodeGenOpt::None)
     addPass(createAArch64AddressTypePromotionPass());
 

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index a66d9ab00f4bb71657a20f053fb8d8d668e95c59..7620cd0a463c2093d4a95a8760f5972fda52f958 100644 (file)
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -1170,12 +1170,6 @@ ARMTargetLowering::createFastISel(FunctionLoweringInfo &funcInfo,
   return ARM::createFastISel(funcInfo, libInfo);
 }
 
-/// getMaximalGlobalOffset - Returns the maximal possible offset which can
-/// be used for loads / stores from the global.
-unsigned ARMTargetLowering::getMaximalGlobalOffset() const {
-  return (Subtarget->isThumb1Only() ? 127 : 4095);
-}
-
 Sched::Preference ARMTargetLowering::getSchedulingPreference(SDNode *N) const {
   unsigned NumVals = N->getNumValues();
   if (!NumVals)

diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index 2544be082342059c773500c87554a3a900f48d0f..12513370077132e9f00623856491fa60e84a668e 100644 (file)
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -353,10 +353,6 @@ namespace llvm {
     /// specified value type.
     const TargetRegisterClass *getRegClassFor(MVT VT) const override;
 
-    /// getMaximalGlobalOffset - Returns the maximal possible offset which can
-    /// be used for loads / stores from the global.
-    unsigned getMaximalGlobalOffset() const override;
-
     /// Returns true if a cast between SrcAS and DestAS is a noop.
     bool isNoopAddrSpaceCast(unsigned SrcAS, unsigned DestAS) const override {
       // Addrspacecasts are always noops.

diff --git a/lib/Target/ARM/ARMTargetMachine.cpp b/lib/Target/ARM/ARMTargetMachine.cpp
index 11fbb5c3e303fa93ca201069dd184d0fc3d3e52a..a97a058f2aa7deddad1e24e67a2f9f0b0467670a 100644 (file)
--- a/lib/Target/ARM/ARMTargetMachine.cpp
+++ b/lib/Target/ARM/ARMTargetMachine.cpp
@@ -326,7 +326,12 @@ void ARMPassConfig::addIRPasses() {
 
 bool ARMPassConfig::addPreISel() {
   if (TM->getOptLevel() != CodeGenOpt::None)
-    addPass(createGlobalMergePass(TM));
+    // FIXME: This is using the thumb1 only constant value for
+    // maximal global offset for merging globals. We may want
+    // to look into using the old value for non-thumb1 code of
+    // 4095 based on the TargetMachine, but this starts to become
+    // tricky when doing code gen per function.
+    addPass(createGlobalMergePass(TM, 127));
 
   return false;
 }