Move several SelectionDAG-independent utility functions out of the

SelectionDAG directory and into a new Analysis.cpp file.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101975 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 285 insertions, 0 deletions

diff --git a/lib/CodeGen/Analysis.cpp b/lib/CodeGen/Analysis.cpp
new file mode 100644
index 0000000000..f71eee5d01
--- /dev/null
+++ b/lib/CodeGen/Analysis.cpp
@@ -0,0 +1,285 @@
+//===-- Analysis.cpp - CodeGen LLVM IR Analysis Utilities --*- C++ ------*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines several CodeGen-specific LLVM IR analysis utilties.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/Analysis.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Module.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/MathExtras.h"
+using namespace llvm;
+
+/// ComputeLinearIndex - Given an LLVM IR aggregate type and a sequence
+/// of insertvalue or extractvalue indices that identify a member, return
+/// the linearized index of the start of the member.
+///
+unsigned llvm::ComputeLinearIndex(const TargetLowering &TLI, const Type *Ty,
+                                  const unsigned *Indices,
+                                  const unsigned *IndicesEnd,
+                                  unsigned CurIndex) {
+  // Base case: We're done.
+  if (Indices && Indices == IndicesEnd)
+    return CurIndex;
+
+  // Given a struct type, recursively traverse the elements.
+  if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+    for (StructType::element_iterator EB = STy->element_begin(),
+                                      EI = EB,
+                                      EE = STy->element_end();
+        EI != EE; ++EI) {
+      if (Indices && *Indices == unsigned(EI - EB))
+        return ComputeLinearIndex(TLI, *EI, Indices+1, IndicesEnd, CurIndex);
+      CurIndex = ComputeLinearIndex(TLI, *EI, 0, 0, CurIndex);
+    }
+    return CurIndex;
+  }
+  // Given an array type, recursively traverse the elements.
+  else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+    const Type *EltTy = ATy->getElementType();
+    for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) {
+      if (Indices && *Indices == i)
+        return ComputeLinearIndex(TLI, EltTy, Indices+1, IndicesEnd, CurIndex);
+      CurIndex = ComputeLinearIndex(TLI, EltTy, 0, 0, CurIndex);
+    }
+    return CurIndex;
+  }
+  // We haven't found the type we're looking for, so keep searching.
+  return CurIndex + 1;
+}
+
+/// ComputeValueVTs - Given an LLVM IR type, compute a sequence of
+/// EVTs that represent all the individual underlying
+/// non-aggregate types that comprise it.
+///
+/// If Offsets is non-null, it points to a vector to be filled in
+/// with the in-memory offsets of each of the individual values.
+///
+void llvm::ComputeValueVTs(const TargetLowering &TLI, const Type *Ty,
+                           SmallVectorImpl<EVT> &ValueVTs,
+                           SmallVectorImpl<uint64_t> *Offsets,
+                           uint64_t StartingOffset) {
+  // Given a struct type, recursively traverse the elements.
+  if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+    const StructLayout *SL = TLI.getTargetData()->getStructLayout(STy);
+    for (StructType::element_iterator EB = STy->element_begin(),
+                                      EI = EB,
+                                      EE = STy->element_end();
+         EI != EE; ++EI)
+      ComputeValueVTs(TLI, *EI, ValueVTs, Offsets,
+                      StartingOffset + SL->getElementOffset(EI - EB));
+    return;
+  }
+  // Given an array type, recursively traverse the elements.
+  if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+    const Type *EltTy = ATy->getElementType();
+    uint64_t EltSize = TLI.getTargetData()->getTypeAllocSize(EltTy);
+    for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i)
+      ComputeValueVTs(TLI, EltTy, ValueVTs, Offsets,
+                      StartingOffset + i * EltSize);
+    return;
+  }
+  // Interpret void as zero return values.
+  if (Ty->isVoidTy())
+    return;
+  // Base case: we can get an EVT for this LLVM IR type.
+  ValueVTs.push_back(TLI.getValueType(Ty));
+  if (Offsets)
+    Offsets->push_back(StartingOffset);
+}
+
+/// ExtractTypeInfo - Returns the type info, possibly bitcast, encoded in V.
+GlobalVariable *llvm::ExtractTypeInfo(Value *V) {
+  V = V->stripPointerCasts();
+  GlobalVariable *GV = dyn_cast<GlobalVariable>(V);
+
+  if (GV && GV->getName() == ".llvm.eh.catch.all.value") {
+    assert(GV->hasInitializer() &&
+           "The EH catch-all value must have an initializer");
+    Value *Init = GV->getInitializer();
+    GV = dyn_cast<GlobalVariable>(Init);
+    if (!GV) V = cast<ConstantPointerNull>(Init);
+  }
+
+  assert((GV || isa<ConstantPointerNull>(V)) &&
+         "TypeInfo must be a global variable or NULL");
+  return GV;
+}
+
+/// hasInlineAsmMemConstraint - Return true if the inline asm instruction being
+/// processed uses a memory 'm' constraint.
+bool
+llvm::hasInlineAsmMemConstraint(std::vector<InlineAsm::ConstraintInfo> &CInfos,
+                                const TargetLowering &TLI) {
+  for (unsigned i = 0, e = CInfos.size(); i != e; ++i) {
+    InlineAsm::ConstraintInfo &CI = CInfos[i];
+    for (unsigned j = 0, ee = CI.Codes.size(); j != ee; ++j) {
+      TargetLowering::ConstraintType CType = TLI.getConstraintType(CI.Codes[j]);
+      if (CType == TargetLowering::C_Memory)
+        return true;
+    }
+
+    // Indirect operand accesses access memory.
+    if (CI.isIndirect)
+      return true;
+  }
+
+  return false;
+}
+
+/// getFCmpCondCode - Return the ISD condition code corresponding to
+/// the given LLVM IR floating-point condition code.  This includes
+/// consideration of global floating-point math flags.
+///
+ISD::CondCode llvm::getFCmpCondCode(FCmpInst::Predicate Pred) {
+  ISD::CondCode FPC, FOC;
+  switch (Pred) {
+  case FCmpInst::FCMP_FALSE: FOC = FPC = ISD::SETFALSE; break;
+  case FCmpInst::FCMP_OEQ:   FOC = ISD::SETEQ; FPC = ISD::SETOEQ; break;
+  case FCmpInst::FCMP_OGT:   FOC = ISD::SETGT; FPC = ISD::SETOGT; break;
+  case FCmpInst::FCMP_OGE:   FOC = ISD::SETGE; FPC = ISD::SETOGE; break;
+  case FCmpInst::FCMP_OLT:   FOC = ISD::SETLT; FPC = ISD::SETOLT; break;
+  case FCmpInst::FCMP_OLE:   FOC = ISD::SETLE; FPC = ISD::SETOLE; break;
+  case FCmpInst::FCMP_ONE:   FOC = ISD::SETNE; FPC = ISD::SETONE; break;
+  case FCmpInst::FCMP_ORD:   FOC = FPC = ISD::SETO;   break;
+  case FCmpInst::FCMP_UNO:   FOC = FPC = ISD::SETUO;  break;
+  case FCmpInst::FCMP_UEQ:   FOC = ISD::SETEQ; FPC = ISD::SETUEQ; break;
+  case FCmpInst::FCMP_UGT:   FOC = ISD::SETGT; FPC = ISD::SETUGT; break;
+  case FCmpInst::FCMP_UGE:   FOC = ISD::SETGE; FPC = ISD::SETUGE; break;
+  case FCmpInst::FCMP_ULT:   FOC = ISD::SETLT; FPC = ISD::SETULT; break;
+  case FCmpInst::FCMP_ULE:   FOC = ISD::SETLE; FPC = ISD::SETULE; break;
+  case FCmpInst::FCMP_UNE:   FOC = ISD::SETNE; FPC = ISD::SETUNE; break;
+  case FCmpInst::FCMP_TRUE:  FOC = FPC = ISD::SETTRUE; break;
+  default:
+    llvm_unreachable("Invalid FCmp predicate opcode!");
+    FOC = FPC = ISD::SETFALSE;
+    break;
+  }
+  if (FiniteOnlyFPMath())
+    return FOC;
+  else
+    return FPC;
+}
+
+/// getICmpCondCode - Return the ISD condition code corresponding to
+/// the given LLVM IR integer condition code.
+///
+ISD::CondCode llvm::getICmpCondCode(ICmpInst::Predicate Pred) {
+  switch (Pred) {
+  case ICmpInst::ICMP_EQ:  return ISD::SETEQ;
+  case ICmpInst::ICMP_NE:  return ISD::SETNE;
+  case ICmpInst::ICMP_SLE: return ISD::SETLE;
+  case ICmpInst::ICMP_ULE: return ISD::SETULE;
+  case ICmpInst::ICMP_SGE: return ISD::SETGE;
+  case ICmpInst::ICMP_UGE: return ISD::SETUGE;
+  case ICmpInst::ICMP_SLT: return ISD::SETLT;
+  case ICmpInst::ICMP_ULT: return ISD::SETULT;
+  case ICmpInst::ICMP_SGT: return ISD::SETGT;
+  case ICmpInst::ICMP_UGT: return ISD::SETUGT;
+  default:
+    llvm_unreachable("Invalid ICmp predicate opcode!");
+    return ISD::SETNE;
+  }
+}
+
+/// Test if the given instruction is in a position to be optimized
+/// with a tail-call. This roughly means that it's in a block with
+/// a return and there's nothing that needs to be scheduled
+/// between it and the return.
+///
+/// This function only tests target-independent requirements.
+bool llvm::isInTailCallPosition(ImmutableCallSite CS, Attributes CalleeRetAttr,
+                                const TargetLowering &TLI) {
+  const Instruction *I = CS.getInstruction();
+  const BasicBlock *ExitBB = I->getParent();
+  const TerminatorInst *Term = ExitBB->getTerminator();
+  const ReturnInst *Ret = dyn_cast<ReturnInst>(Term);
+  const Function *F = ExitBB->getParent();
+
+  // The block must end in a return statement or unreachable.
+  //
+  // FIXME: Decline tailcall if it's not guaranteed and if the block ends in
+  // an unreachable, for now. The way tailcall optimization is currently
+  // implemented means it will add an epilogue followed by a jump. That is
+  // not profitable. Also, if the callee is a special function (e.g.
+  // longjmp on x86), it can end up causing miscompilation that has not
+  // been fully understood.
+  if (!Ret &&
+      (!GuaranteedTailCallOpt || !isa<UnreachableInst>(Term))) return false;
+
+  // If I will have a chain, make sure no other instruction that will have a
+  // chain interposes between I and the return.
+  if (I->mayHaveSideEffects() || I->mayReadFromMemory() ||
+      !I->isSafeToSpeculativelyExecute())
+    for (BasicBlock::const_iterator BBI = prior(prior(ExitBB->end())); ;
+         --BBI) {
+      if (&*BBI == I)
+        break;
+      // Debug info intrinsics do not get in the way of tail call optimization.
+      if (isa<DbgInfoIntrinsic>(BBI))
+        continue;
+      if (BBI->mayHaveSideEffects() || BBI->mayReadFromMemory() ||
+          !BBI->isSafeToSpeculativelyExecute())
+        return false;
+    }
+
+  // If the block ends with a void return or unreachable, it doesn't matter
+  // what the call's return type is.
+  if (!Ret || Ret->getNumOperands() == 0) return true;
+
+  // If the return value is undef, it doesn't matter what the call's
+  // return type is.
+  if (isa<UndefValue>(Ret->getOperand(0))) return true;
+
+  // Conservatively require the attributes of the call to match those of
+  // the return. Ignore noalias because it doesn't affect the call sequence.
+  unsigned CallerRetAttr = F->getAttributes().getRetAttributes();
+  if ((CalleeRetAttr ^ CallerRetAttr) & ~Attribute::NoAlias)
+    return false;
+
+  // It's not safe to eliminate the sign / zero extension of the return value.
+  if ((CallerRetAttr & Attribute::ZExt) || (CallerRetAttr & Attribute::SExt))
+    return false;
+
+  // Otherwise, make sure the unmodified return value of I is the return value.
+  for (const Instruction *U = dyn_cast<Instruction>(Ret->getOperand(0)); ;
+       U = dyn_cast<Instruction>(U->getOperand(0))) {
+    if (!U)
+      return false;
+    if (!U->hasOneUse())
+      return false;
+    if (U == I)
+      break;
+    // Check for a truly no-op truncate.
+    if (isa<TruncInst>(U) &&
+        TLI.isTruncateFree(U->getOperand(0)->getType(), U->getType()))
+      continue;
+    // Check for a truly no-op bitcast.
+    if (isa<BitCastInst>(U) &&
+        (U->getOperand(0)->getType() == U->getType() ||
+         (U->getOperand(0)->getType()->isPointerTy() &&
+          U->getType()->isPointerTy())))
+      continue;
+    // Otherwise it's not a true no-op.
+    return false;
+  }
+
+  return true;
+}
+