Move getOrEnforceKnownAlignment out of instcombine into Transforms/Utils.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122554 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 115 insertions, 103 deletions

diff --git a/include/llvm/Transforms/Utils/Local.h b/include/llvm/Transforms/Utils/Local.h
index dc18f3c4c7..26b5dd8365 100644
--- a/include/llvm/Transforms/Utils/Local.h
+++ b/include/llvm/Transforms/Utils/Local.h
@@ -145,6 +145,18 @@ AllocaInst *DemoteRegToStack(Instruction &X,
 /// The phi node is deleted and it returns the pointer to the alloca inserted. 
 AllocaInst *DemotePHIToStack(PHINode *P, Instruction *AllocaPoint = 0);
 
+/// getOrEnforceKnownAlignment - If the specified pointer has an alignment that
+/// we can determine, return it, otherwise return 0.  If PrefAlign is specified,
+/// and it is more than the alignment of the ultimate object, see if we can
+/// increase the alignment of the ultimate object, making this check succeed.
+unsigned getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
+                                    const TargetData *TD = 0);
+
+/// getKnownAlignment - Try to infer an alignment for the specified pointer.
+static inline unsigned getKnownAlignment(Value *V, const TargetData *TD = 0) {
+  return getOrEnforceKnownAlignment(V, 0, TD);
+}
+
 } // End llvm namespace
 
 #endif
diff --git a/lib/Transforms/InstCombine/InstCombine.h b/lib/Transforms/InstCombine/InstCombine.h
index 3a58708166..81b5b7ea6d 100644
--- a/lib/Transforms/InstCombine/InstCombine.h
+++ b/lib/Transforms/InstCombine/InstCombine.h
@@ -348,10 +348,6 @@ private:
 
 
   Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
-
-  unsigned GetOrEnforceKnownAlignment(Value *V,
-                                      unsigned PrefAlign = 0);
-
 };
 
       
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index f872a9b5ae..35f9791472 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -17,6 +17,7 @@
 #include "llvm/Target/TargetData.h"
 #include "llvm/Analysis/MemoryBuiltins.h"
 #include "llvm/Transforms/Utils/BuildLibCalls.h"
+#include "llvm/Transforms/Utils/Local.h"
 using namespace llvm;
 
 /// getPromotedType - Return the specified type promoted as it would be to pass
@@ -29,100 +30,10 @@ static const Type *getPromotedType(const Type *Ty) {
   return Ty;
 }
 
-/// EnforceKnownAlignment - If the specified pointer points to an object that
-/// we control, modify the object's alignment to PrefAlign. This isn't
-/// often possible though. If alignment is important, a more reliable approach
-/// is to simply align all global variables and allocation instructions to
-/// their preferred alignment from the beginning.
-///
-static unsigned EnforceKnownAlignment(Value *V,
-                                      unsigned Align, unsigned PrefAlign) {
-
-  User *U = dyn_cast<User>(V);
-  if (!U) return Align;
-
-  switch (Operator::getOpcode(U)) {
-  default: break;
-  case Instruction::BitCast:
-    return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
-  case Instruction::GetElementPtr: {
-    // If all indexes are zero, it is just the alignment of the base pointer.
-    bool AllZeroOperands = true;
-    for (User::op_iterator i = U->op_begin() + 1, e = U->op_end(); i != e; ++i)
-      if (!isa<Constant>(*i) ||
-          !cast<Constant>(*i)->isNullValue()) {
-        AllZeroOperands = false;
-        break;
-      }
-
-    if (AllZeroOperands) {
-      // Treat this like a bitcast.
-      return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
-    }
-    return Align;
-  }
-  case Instruction::Alloca: {
-    AllocaInst *AI = cast<AllocaInst>(V);
-    // If there is a requested alignment and if this is an alloca, round up.
-    if (AI->getAlignment() >= PrefAlign)
-      return AI->getAlignment();
-    AI->setAlignment(PrefAlign);
-    return PrefAlign;
-  }
-  }
-
-  if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
-    // If there is a large requested alignment and we can, bump up the alignment
-    // of the global.
-    if (GV->isDeclaration()) return Align;
-    
-    if (GV->getAlignment() >= PrefAlign)
-      return GV->getAlignment();
-    // We can only increase the alignment of the global if it has no alignment
-    // specified or if it is not assigned a section.  If it is assigned a
-    // section, the global could be densely packed with other objects in the
-    // section, increasing the alignment could cause padding issues.
-    if (!GV->hasSection() || GV->getAlignment() == 0)
-      GV->setAlignment(PrefAlign);
-    return GV->getAlignment();
-  }
-
-  return Align;
-}
-
-/// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
-/// we can determine, return it, otherwise return 0.  If PrefAlign is specified,
-/// and it is more than the alignment of the ultimate object, see if we can
-/// increase the alignment of the ultimate object, making this check succeed.
-unsigned InstCombiner::GetOrEnforceKnownAlignment(Value *V,
-                                                  unsigned PrefAlign) {
-  assert(V->getType()->isPointerTy() &&
-         "GetOrEnforceKnownAlignment expects a pointer!");
-  unsigned BitWidth = TD ? TD->getPointerSizeInBits() : 64;
-  APInt Mask = APInt::getAllOnesValue(BitWidth);
-  APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
-  ComputeMaskedBits(V, Mask, KnownZero, KnownOne);
-  unsigned TrailZ = KnownZero.countTrailingOnes();
-
-  // Avoid trouble with rediculously large TrailZ values, such as
-  // those computed from a null pointer.
-  TrailZ = std::min(TrailZ, unsigned(sizeof(unsigned) * CHAR_BIT - 1));
-
-  unsigned Align = 1u << std::min(BitWidth - 1, TrailZ);
-
-  // LLVM doesn't support alignments larger than this currently.
-  Align = std::min(Align, +Value::MaximumAlignment);
-
-  if (PrefAlign > Align)
-    Align = EnforceKnownAlignment(V, Align, PrefAlign);
-  
-    // We don't need to make any adjustment.
-  return Align;
-}
 
 Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
-  unsigned DstAlign = GetOrEnforceKnownAlignment(MI->getArgOperand(0));
-  unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getArgOperand(1));
+  unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), TD);
+  unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), TD);
   unsigned MinAlign = std::min(DstAlign, SrcAlign);
   unsigned CopyAlign = MI->getAlignment();
 
@@ -211,7 +122,7 @@ Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
 }
 
 Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
-  unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest());
+  unsigned Alignment = getKnownAlignment(MI->getDest());
   if (MI->getAlignment() < Alignment) {
     MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
                                              Alignment, false));
@@ -611,7 +522,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
   case Intrinsic::x86_sse2_loadu_dq:
     // Turn PPC lvx     -> load if the pointer is known aligned.
     // Turn X86 loadups -> load if the pointer is known aligned.
-    if (GetOrEnforceKnownAlignment(II->getArgOperand(0), 16) >= 16) {
+    if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, TD) >= 16) {
       Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0),
                                          PointerType::getUnqual(II->getType()));
       return new LoadInst(Ptr);
@@ -620,7 +531,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
   case Intrinsic::ppc_altivec_stvx:
   case Intrinsic::ppc_altivec_stvxl:
     // Turn stvx -> store if the pointer is known aligned.
-    if (GetOrEnforceKnownAlignment(II->getArgOperand(1), 16) >= 16) {
+    if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, TD) >= 16) {
       const Type *OpPtrTy = 
         PointerType::getUnqual(II->getArgOperand(0)->getType());
       Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy);
@@ -631,7 +542,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
   case Intrinsic::x86_sse2_storeu_pd:
   case Intrinsic::x86_sse2_storeu_dq:
     // Turn X86 storeu -> store if the pointer is known aligned.
-    if (GetOrEnforceKnownAlignment(II->getArgOperand(0), 16) >= 16) {
+    if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, TD) >= 16) {
       const Type *OpPtrTy = 
         PointerType::getUnqual(II->getArgOperand(1)->getType());
       Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), OpPtrTy);
@@ -718,7 +629,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
   case Intrinsic::arm_neon_vst2lane:
   case Intrinsic::arm_neon_vst3lane:
   case Intrinsic::arm_neon_vst4lane: {
-    unsigned MemAlign = GetOrEnforceKnownAlignment(II->getArgOperand(0));
+    unsigned MemAlign = getKnownAlignment(II->getArgOperand(0));
     unsigned AlignArg = II->getNumArgOperands() - 1;
     ConstantInt *IntrAlign = dyn_cast<ConstantInt>(II->getArgOperand(AlignArg));
     if (IntrAlign && IntrAlign->getZExtValue() < MemAlign) {
diff --git a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 992a5d9f6b..c2a8b7cbc6 100644
--- a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -145,7 +145,7 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
   // Attempt to improve the alignment.
   if (TD) {
     unsigned KnownAlign =
-      GetOrEnforceKnownAlignment(Op, TD->getPrefTypeAlignment(LI.getType()));
+      getOrEnforceKnownAlignment(Op, TD->getPrefTypeAlignment(LI.getType()),TD);
     unsigned LoadAlign = LI.getAlignment();
     unsigned EffectiveLoadAlign = LoadAlign != 0 ? LoadAlign :
       TD->getABITypeAlignment(LI.getType());
@@ -416,7 +416,8 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
   // Attempt to improve the alignment.
   if (TD) {
     unsigned KnownAlign =
-      GetOrEnforceKnownAlignment(Ptr, TD->getPrefTypeAlignment(Val->getType()));
+      getOrEnforceKnownAlignment(Ptr, TD->getPrefTypeAlignment(Val->getType()),
+                                 TD);
     unsigned StoreAlign = SI.getAlignment();
     unsigned EffectiveStoreAlign = StoreAlign != 0 ? StoreAlign :
       TD->getABITypeAlignment(Val->getType());
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 383efcec10..77add4a896 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -25,6 +25,7 @@
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/ProfileInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Target/TargetData.h"
 #include "llvm/Support/CFG.h"
 #include "llvm/Support/Debug.h"
@@ -642,3 +643,94 @@ bool llvm::EliminateDuplicatePHINodes(BasicBlock *BB) {
 
   return Changed;
 }
+
+/// enforceKnownAlignment - If the specified pointer points to an object that
+/// we control, modify the object's alignment to PrefAlign. This isn't
+/// often possible though. If alignment is important, a more reliable approach
+/// is to simply align all global variables and allocation instructions to
+/// their preferred alignment from the beginning.
+///
+unsigned enforceKnownAlignment(Value *V, unsigned Align, unsigned PrefAlign) {
+
+  User *U = dyn_cast<User>(V);
+  if (!U) return Align;
+
+  switch (Operator::getOpcode(U)) {
+  default: break;
+  case Instruction::BitCast:
+    return enforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
+  case Instruction::GetElementPtr: {
+    // If all indexes are zero, it is just the alignment of the base pointer.
+    bool AllZeroOperands = true;
+    for (User::op_iterator i = U->op_begin() + 1, e = U->op_end(); i != e; ++i)
+      if (!isa<Constant>(*i) ||
+          !cast<Constant>(*i)->isNullValue()) {
+        AllZeroOperands = false;
+        break;
+      }
+
+    if (AllZeroOperands) {
+      // Treat this like a bitcast.
+      return enforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
+    }
+    return Align;
+  }
+  case Instruction::Alloca: {
+    AllocaInst *AI = cast<AllocaInst>(V);
+    // If there is a requested alignment and if this is an alloca, round up.
+    if (AI->getAlignment() >= PrefAlign)
+      return AI->getAlignment();
+    AI->setAlignment(PrefAlign);
+    return PrefAlign;
+  }
+  }
+
+  if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
+    // If there is a large requested alignment and we can, bump up the alignment
+    // of the global.
+    if (GV->isDeclaration()) return Align;
+    
+    if (GV->getAlignment() >= PrefAlign)
+      return GV->getAlignment();
+    // We can only increase the alignment of the global if it has no alignment
+    // specified or if it is not assigned a section.  If it is assigned a
+    // section, the global could be densely packed with other objects in the
+    // section, increasing the alignment could cause padding issues.
+    if (!GV->hasSection() || GV->getAlignment() == 0)
+      GV->setAlignment(PrefAlign);
+    return GV->getAlignment();
+  }
+
+  return Align;
+}
+
+/// getOrEnforceKnownAlignment - If the specified pointer has an alignment that
+/// we can determine, return it, otherwise return 0.  If PrefAlign is specified,
+/// and it is more than the alignment of the ultimate object, see if we can
+/// increase the alignment of the ultimate object, making this check succeed.
+unsigned llvm::getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign,
+                                          const TargetData *TD) {
+  assert(V->getType()->isPointerTy() &&
+         "getOrEnforceKnownAlignment expects a pointer!");
+  unsigned BitWidth = TD ? TD->getPointerSizeInBits() : 64;
+  APInt Mask = APInt::getAllOnesValue(BitWidth);
+  APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+  ComputeMaskedBits(V, Mask, KnownZero, KnownOne);
+  unsigned TrailZ = KnownZero.countTrailingOnes();
+  
+  // Avoid trouble with rediculously large TrailZ values, such as
+  // those computed from a null pointer.
+  TrailZ = std::min(TrailZ, unsigned(sizeof(unsigned) * CHAR_BIT - 1));
+  
+  unsigned Align = 1u << std::min(BitWidth - 1, TrailZ);
+  
+  // LLVM doesn't support alignments larger than this currently.
+  Align = std::min(Align, +Value::MaximumAlignment);
+  
+  if (PrefAlign > Align)
+    Align = enforceKnownAlignment(V, Align, PrefAlign);
+    
+  // We don't need to make any adjustment.
+  return Align;
+}
+