Add new getValueAsBitsInit 'high-level' method
[oota-llvm.git] / utils / TableGen / CodeEmitterGen.cpp
index b32a38aa5fe4da9595ee4f6945950de616e4ce4a..dc61f8f507fa441211d63b2a99a377e11d6f2824 100644 (file)
@@ -1,18 +1,15 @@
-#include "Record.h"
-#include "CodeEmitterGen.h"
-#include <ostream>
+//===- CodeEmitterGen.cpp - Code Emitter Generator ------------------------===//
+//
+// FIXME: Document.
+//
+//===----------------------------------------------------------------------===//
 
-void CodeEmitterGen::createEmitter(std::ostream &o) {
-  std::vector<Record*> Insts;
-
-  const std::map<std::string, Record*> &Defs = Records.getDefs();
-  Record *Inst = Records.getClass("Instruction");
-  assert(Inst && "Couldn't find Instruction class!");
+#include "CodeEmitterGen.h"
+#include "Record.h"
+#include "Support/Statistic.h"
 
-  for (std::map<std::string, Record*>::const_iterator I = Defs.begin(),
-        E = Defs.end(); I != E; ++I)
-    if (I->second->isSubClassOf(Inst))
-      Insts.push_back(I->second);
+void CodeEmitterGen::run(std::ostream &o) {
+  std::vector<Record*> Insts = Records.getAllDerivedDefinitions("Instruction");
 
   std::string Namespace = "V9::";
   std::string ClassName = "SparcV9CodeEmitter::";
@@ -21,38 +18,32 @@ void CodeEmitterGen::createEmitter(std::ostream &o) {
   o << "unsigned " << ClassName
     << "getBinaryCodeForInstr(MachineInstr &MI) {\n"
     << "  unsigned Value = 0;\n"
-    << "  std::cerr << MI;\n"
+    << "  DEBUG(std::cerr << MI);\n"
     << "  switch (MI.getOpcode()) {\n";
   for (std::vector<Record*>::iterator I = Insts.begin(), E = Insts.end();
-       I != E; ++I)
-  {
+       I != E; ++I) {
     Record *R = *I;
     o << "    case " << Namespace << R->getName() << ": {\n"
-      << "      std::cerr << \"Emitting " << R->getName() << "\\n\";\n";
-
-    const RecordVal *InstVal = R->getValue("Inst");
-    Init *InitVal = InstVal->getValue();
+      << "      DEBUG(std::cerr << \"Emitting " << R->getName() << "\\n\");\n";
 
-    assert(dynamic_cast<BitsInit*>(InitVal) &&
-           "Can only handle undefined bits<> types!");
-    BitsInit *BI = (BitsInit*)InitVal;
+    BitsInit *BI = R->getValueAsBitsInit("Inst");
 
     unsigned Value = 0;
     const std::vector<RecordVal> &Vals = R->getValues();
 
-    o << "      // prefilling: ";
+    DEBUG(o << "      // prefilling: ");
     // Start by filling in fixed values...
     for (unsigned i = 0, e = BI->getNumBits(); i != e; ++i) {
       if (BitInit *B = dynamic_cast<BitInit*>(BI->getBit(e-i-1))) {
         Value |= B->getValue() << (e-i-1);
-        o << B->getValue();
+        DEBUG(o << B->getValue());
       } else {
-        o << "0";
+        DEBUG(o << "0");
       }
     }
-    o << "\n";
+    DEBUG(o << "\n");
 
-    o << "      // " << *InstVal << "\n";
+    DEBUG(o << "      // " << *R->getValue("Inst") << "\n");
     o << "      Value = " << Value << "U;\n\n";
     
     // Loop over all of the fields in the instruction adding in any
@@ -60,11 +51,12 @@ void CodeEmitterGen::createEmitter(std::ostream &o) {
     //
     unsigned op = 0;
     std::map<const std::string,unsigned> OpOrder;
+    std::map<const std::string,bool> OpContinuous;
     for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
       if (Vals[i].getName() != "Inst" && 
           !Vals[i].getValue()->isComplete() &&
+          /* ignore annul and predict bits since no one sets them yet */
           Vals[i].getName() != "annul" && 
-          Vals[i].getName() != "cc" &&
           Vals[i].getName() != "predict")
       {
         o << "      // op" << op << ": " << Vals[i].getName() << "\n"
@@ -72,30 +64,132 @@ void CodeEmitterGen::createEmitter(std::ostream &o) {
           <<" = getMachineOpValue(MI, MI.getOperand("<<op<<"));\n";
         //<< "      MachineOperand &op" << op <<" = MI.getOperand("<<op<<");\n";
         OpOrder[Vals[i].getName()] = op++;
+
+        // Is the operand continuous? If so, we can just mask and OR it in
+        // instead of doing it bit-by-bit, saving a lot in runtime cost.        
+        const BitsInit *InstInit = BI;
+        int beginBitInVar = -1, endBitInVar = -1,
+          beginBitInInst = -1, endBitInInst = -1;
+        bool continuous = true;
+
+        for (int bit = InstInit->getNumBits()-1; bit >= 0; --bit) {
+          if (VarBitInit *VBI =
+              dynamic_cast<VarBitInit*>(InstInit->getBit(bit))) {
+            TypedInit *TI = VBI->getVariable();
+            if (VarInit *VI = dynamic_cast<VarInit*>(TI)) {
+              // only process the current variable
+              if (VI->getName() != Vals[i].getName())
+                continue;
+
+              if (beginBitInVar == -1)
+                beginBitInVar = VBI->getBitNum();
+
+              if (endBitInVar == -1)
+                endBitInVar = VBI->getBitNum();
+              else {
+                if (endBitInVar == (int)VBI->getBitNum() + 1)
+                  endBitInVar = VBI->getBitNum();
+                else {
+                  continuous = false;
+                  break;
+                }
+              }
+
+              if (beginBitInInst == -1)
+                beginBitInInst = bit;
+              if (endBitInInst == -1)
+                endBitInInst = bit;
+              else {
+                if (endBitInInst == bit + 1)
+                  endBitInInst = bit;
+                else {
+                  continuous = false;
+                  break;
+                }
+              }
+
+              // maintain same distance between bits in field and bits in
+              // instruction. if the relative distances stay the same
+              // throughout,
+              if ((beginBitInVar - (int)VBI->getBitNum()) !=
+                  (beginBitInInst - bit))
+              {
+                continuous = false;
+                break;
+              }
+            }
+          }
+        }
+
+        DEBUG(o << "      // Var: begin = " << beginBitInVar 
+                << ", end = " << endBitInVar
+                << "; Inst: begin = " << beginBitInInst
+                << ", end = " << endBitInInst << "\n");
+
+        if (continuous) {
+          DEBUG(o << "      // continuous: op" << OpOrder[Vals[i].getName()]
+                  << "\n");
+          
+          // Mask off the right bits
+          // Low mask (ie. shift, if necessary)
+          if (endBitInVar != 0) {
+            o << "      op" << OpOrder[Vals[i].getName()]
+              << " >>= " << endBitInVar << ";\n";
+            beginBitInVar -= endBitInVar;
+            endBitInVar = 0;
+          }
+
+          // High mask
+          o << "      op" << OpOrder[Vals[i].getName()]
+            << " &= (1<<" << beginBitInVar+1 << ") - 1;\n";
+
+          // Shift the value to the correct place (according to place in instr)
+          if (endBitInInst != 0)
+            o << "      op" << OpOrder[Vals[i].getName()]
+              << " <<= " << endBitInInst << ";\n";
+
+          // Just OR in the result
+          o << "      Value |= op" << OpOrder[Vals[i].getName()] << ";\n";
+        }
+
+        // otherwise, will be taken care of in the loop below using this value:
+        OpContinuous[Vals[i].getName()] = continuous;
       }
     }
 
-    unsigned Offset = 31;
-    for (int f = Vals.size()-1; f >= 0; --f) {
+    for (unsigned f = 0, e = Vals.size(); f != e; ++f) {
       if (Vals[f].getPrefix()) {
         BitsInit *FieldInitializer = (BitsInit*)Vals[f].getValue();
 
         // Scan through the field looking for bit initializers of the current
         // variable...
         for (int i = FieldInitializer->getNumBits()-1; i >= 0; --i) {
-          if (BitInit *BI=dynamic_cast<BitInit*>(FieldInitializer->getBit(i))){
-            --Offset;
-          } else if (UnsetInit *UI = 
+          if (BitInit *BI=dynamic_cast<BitInit*>(FieldInitializer->getBit(i)))
+          {
+            DEBUG(o << "      // bit init: f: " << f << ", i: " << i << "\n");
+          } else if (UnsetInit *UI =
                      dynamic_cast<UnsetInit*>(FieldInitializer->getBit(i))) {
-            --Offset;
+            DEBUG(o << "      // unset init: f: " << f << ", i: " << i << "\n");
           } else if (VarBitInit *VBI =
                      dynamic_cast<VarBitInit*>(FieldInitializer->getBit(i))) {
             TypedInit *TI = VBI->getVariable();
             if (VarInit *VI = dynamic_cast<VarInit*>(TI)) {
-              o << "      Value |= getValueBit(op" << OpOrder[VI->getName()]
-                << ", " << VBI->getBitNum()
-                << ")" << " << " << Offset << ";\n";
-              --Offset;
+              // If the bits of the field are laid out consecutively in the
+              // instruction, then instead of separately ORing in bits, just
+              // mask and shift the entire field for efficiency.
+              if (OpContinuous[VI->getName()]) {
+                // already taken care of in the loop above, thus there is no
+                // need to individually OR in the bits
+
+                // for debugging, output the regular version anyway, commented
+                DEBUG(o << "      // Value |= getValueBit(op"
+                        << OpOrder[VI->getName()] << ", " << VBI->getBitNum()
+                        << ")" << " << " << i << ";\n");
+              } else {
+                o << "      Value |= getValueBit(op" << OpOrder[VI->getName()]
+                  << ", " << VBI->getBitNum()
+                  << ")" << " << " << i << ";\n";
+              }
             } else if (FieldInit *FI = dynamic_cast<FieldInit*>(TI)) {
               // FIXME: implement this!
               o << "FIELD INIT not implemented yet!\n";
@@ -103,18 +197,21 @@ void CodeEmitterGen::createEmitter(std::ostream &o) {
               o << "Error: UNIMPLEMENTED\n";
             }
           }
-        } 
+        }
       } else {
-        if (Vals[f].getName() == "annul" || Vals[f].getName() == "predict")
-          --Offset;
+        // ignore annul and predict bits since no one sets them yet
+        if (Vals[f].getName() == "annul" || Vals[f].getName() == "predict") {
+          o << "      // found " << Vals[f].getName() << "\n";
+        }
       }
     }
 
     o << "      break;\n"
       << "    }\n";
   }
+
   o << "  default:\n"
-    << "    std::cerr << \"Not supported instr: \" << MI << \"\\n\";\n"
+    << "    DEBUG(std::cerr << \"Not supported instr: \" << MI << \"\\n\");\n"
     << "    abort();\n"
     << "  }\n"
     << "  return Value;\n"