Add basic functionality for assignment of ints.

This creates a lot of core infrastructure in which to add, with little
effort, quite a bit more to mips fast-isel

Test Plan: simplestore.ll

Reviewers: dsanders

Reviewed By: dsanders

Differential Revision: http://reviews.llvm.org/D3527

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207790 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 167 insertions, 1 deletions

diff --git a/lib/Target/Mips/MipsFastISel.cpp b/lib/Target/Mips/MipsFastISel.cpp
index c85be1e553..eed1f062a3 100644
--- a/lib/Target/Mips/MipsFastISel.cpp
+++ b/lib/Target/Mips/MipsFastISel.cpp
@@ -3,10 +3,12 @@
 
 #include "llvm/CodeGen/FunctionLoweringInfo.h"
 #include "llvm/CodeGen/FastISel.h"
-
 #include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/IR/GlobalAlias.h"
+#include "llvm/IR/GlobalVariable.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetLibraryInfo.h"
+#include "MipsRegisterInfo.h"
 #include "MipsISelLowering.h"
 #include "MipsMachineFunction.h"
 #include "MipsSubtarget.h"
@@ -15,6 +17,21 @@ using namespace llvm;
 
 namespace {
 
+// All possible address modes.
+typedef struct Address {
+  enum { RegBase, FrameIndexBase } BaseType;
+
+  union {
+    unsigned Reg;
+    int FI;
+  } Base;
+
+  int64_t Offset;
+
+  // Innocuous defaults for our address.
+  Address() : BaseType(RegBase), Offset(0) { Base.Reg = 0; }
+} Address;
+
 class MipsFastISel final : public FastISel {
 
   /// Subtarget - Keep a pointer to the MipsSubtarget around so that we can
@@ -46,10 +63,120 @@ public:
   }
 
   bool TargetSelectInstruction(const Instruction *I) override;
+  unsigned TargetMaterializeConstant(const Constant *C) override;
+
+  bool ComputeAddress(const Value *Obj, Address &Addr);
 
+private:
+  bool EmitStore(MVT VT, unsigned SrcReg, Address &Addr,
+                 unsigned Alignment = 0);
   bool SelectRet(const Instruction *I);
+  bool SelectStore(const Instruction *I);
+
+  bool isTypeLegal(Type *Ty, MVT &VT);
+  bool isLoadTypeLegal(Type *Ty, MVT &VT);
+
+  unsigned MaterializeFP(const ConstantFP *CFP, MVT VT);
+  unsigned MaterializeGV(const GlobalValue *GV, MVT VT);
+  unsigned MaterializeInt(const Constant *C, MVT VT);
 };
 
+bool MipsFastISel::isTypeLegal(Type *Ty, MVT &VT) {
+  EVT evt = TLI.getValueType(Ty, true);
+  // Only handle simple types.
+  if (evt == MVT::Other || !evt.isSimple())
+    return false;
+  VT = evt.getSimpleVT();
+
+  // Handle all legal types, i.e. a register that will directly hold this
+  // value.
+  return TLI.isTypeLegal(VT);
+}
+
+bool MipsFastISel::isLoadTypeLegal(Type *Ty, MVT &VT) {
+  if (isTypeLegal(Ty, VT))
+    return true;
+  // We will extend this in a later patch:
+  //   If this is a type than can be sign or zero-extended to a basic operation
+  //   go ahead and accept it now.
+  return false;
+}
+
+bool MipsFastISel::ComputeAddress(const Value *Obj, Address &Addr) {
+  // This construct looks a big awkward but it is how other ports handle this
+  // and as this function is more fully completed, these cases which
+  // return false will have additional code in them.
+  //
+  if (isa<Instruction>(Obj))
+    return false;
+  else if (isa<ConstantExpr>(Obj))
+    return false;
+  Addr.Base.Reg = getRegForValue(Obj);
+  return Addr.Base.Reg != 0;
+}
+
+// Materialize a constant into a register, and return the register
+// number (or zero if we failed to handle it).
+unsigned MipsFastISel::TargetMaterializeConstant(const Constant *C) {
+  EVT CEVT = TLI.getValueType(C->getType(), true);
+
+  // Only handle simple types.
+  if (!CEVT.isSimple())
+    return 0;
+  MVT VT = CEVT.getSimpleVT();
+
+  if (const ConstantFP *CFP = dyn_cast<ConstantFP>(C))
+    return MaterializeFP(CFP, VT);
+  else if (const GlobalValue *GV = dyn_cast<GlobalValue>(C))
+    return MaterializeGV(GV, VT);
+  else if (isa<ConstantInt>(C))
+    return MaterializeInt(C, VT);
+
+  return 0;
+}
+
+bool MipsFastISel::EmitStore(MVT VT, unsigned SrcReg, Address &Addr,
+                             unsigned Alignment) {
+  //
+  // more cases will be handled here in following patches.
+  //
+  if (VT != MVT::i32)
+    return false;
+  BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Mips::SW))
+      .addReg(SrcReg)
+      .addReg(Addr.Base.Reg)
+      .addImm(Addr.Offset);
+  return true;
+}
+
+bool MipsFastISel::SelectStore(const Instruction *I) {
+  Value *Op0 = I->getOperand(0);
+  unsigned SrcReg = 0;
+
+  // Atomic stores need special handling.
+  if (cast<StoreInst>(I)->isAtomic())
+    return false;
+
+  // Verify we have a legal type before going any further.
+  MVT VT;
+  if (!isLoadTypeLegal(I->getOperand(0)->getType(), VT))
+    return false;
+
+  // Get the value to be stored into a register.
+  SrcReg = getRegForValue(Op0);
+  if (SrcReg == 0)
+    return false;
+
+  // See if we can handle this address.
+  Address Addr;
+  if (!ComputeAddress(I->getOperand(1), Addr))
+    return false;
+
+  if (!EmitStore(VT, SrcReg, Addr, cast<StoreInst>(I)->getAlignment()))
+    return false;
+  return true;
+}
+
 bool MipsFastISel::SelectRet(const Instruction *I) {
   const ReturnInst *Ret = cast<ReturnInst>(I);
 
@@ -69,6 +196,8 @@ bool MipsFastISel::TargetSelectInstruction(const Instruction *I) {
   switch (I->getOpcode()) {
   default:
     break;
+  case Instruction::Store:
+    return SelectStore(I);
   case Instruction::Ret:
     return SelectRet(I);
   }
@@ -76,6 +205,43 @@ bool MipsFastISel::TargetSelectInstruction(const Instruction *I) {
 }
 }
 
+unsigned MipsFastISel::MaterializeFP(const ConstantFP *CFP, MVT VT) {
+  return 0;
+}
+
+unsigned MipsFastISel::MaterializeGV(const GlobalValue *GV, MVT VT) {
+  // For now 32-bit only.
+  if (VT != MVT::i32)
+    return 0;
+  const TargetRegisterClass *RC = &Mips::GPR32RegClass;
+  unsigned DestReg = createResultReg(RC);
+  const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
+  bool IsThreadLocal = GVar && GVar->isThreadLocal();
+  // TLS not supported at this time.
+  if (IsThreadLocal)
+    return 0;
+  BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Mips::LW), DestReg)
+      .addReg(MFI->getGlobalBaseReg())
+      .addGlobalAddress(GV, 0, MipsII::MO_GOT);
+  return DestReg;
+}
+unsigned MipsFastISel::MaterializeInt(const Constant *C, MVT VT) {
+  if (VT != MVT::i32)
+    return 0;
+  const TargetRegisterClass *RC = &Mips::GPR32RegClass;
+  // If the constant is in range, use a load-immediate.
+  const ConstantInt *CI = cast<ConstantInt>(C);
+  if (isInt<16>(CI->getSExtValue())) {
+    unsigned Opc = Mips::ADDiu;
+    unsigned ImmReg = createResultReg(RC);
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Opc), ImmReg)
+        .addReg(Mips::ZERO)
+        .addImm(CI->getSExtValue());
+    return ImmReg;
+  }
+  return 0;
+}
+
 namespace llvm {
 FastISel *Mips::createFastISel(FunctionLoweringInfo &funcInfo,
                                const TargetLibraryInfo *libInfo) {