Teach TableGen to pre-calculate register enum values when creating the

CodeGenRegister entries. Use this information to more intelligently build
the literal register entires in the DAGISel matcher table. Specifically,
use a single-byte OPC_EmitRegister entry for registers with a value of
less than 256 and OPC_EmitRegister2 entry for registers with a larger value.

rdar://9066491



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127456 91177308-0d34-0410-b5e6-96231b3b80d8

utils/TableGen/DAGISelEmitter.cpp

@@ -148,12 +148,8 @@ void DAGISelEmitter::run(raw_ostream &OS) {
   Matcher *TheMatcher = new ScopeMatcher(&PatternMatchers[0],
                                          PatternMatchers.size());
 
-  CodeGenTarget Target(Records);
-  const std::vector<CodeGenRegister> &Registers = Target.getRegisters();
-  bool useEmitRegister2 = Registers.size() > 255;
-
   TheMatcher = OptimizeMatcher(TheMatcher, CGP);
   //Matcher->dump();
-  EmitMatcherTable(TheMatcher, CGP, useEmitRegister2, OS);
+  EmitMatcherTable(TheMatcher, CGP, OS);
   delete TheMatcher;
 }

utils/TableGen/DAGISelMatcher.h

@@ -17,6 +17,7 @@
 #include "llvm/Support/Casting.h"
 
 namespace llvm {
+  struct CodeGenRegister;
   class CodeGenDAGPatterns;
   class Matcher;
   class PatternToMatch;
@@ -29,7 +30,7 @@ Matcher *ConvertPatternToMatcher(const PatternToMatch &Pattern,unsigned Variant,
                                  const CodeGenDAGPatterns &CGP);
 Matcher *OptimizeMatcher(Matcher *Matcher, const CodeGenDAGPatterns &CGP);
 void EmitMatcherTable(const Matcher *Matcher, const CodeGenDAGPatterns &CGP,
-                      bool useEmitRegister2, raw_ostream &OS);
+                      raw_ostream &OS);
 
 
 /// Matcher - Base class for all the the DAG ISel Matcher representation
@@ -816,13 +817,13 @@ private:
 class EmitRegisterMatcher : public Matcher {
   /// Reg - The def for the register that we're emitting.  If this is null, then
   /// this is a reference to zero_reg.
-  Record *Reg;
+  const CodeGenRegister *Reg;
   MVT::SimpleValueType VT;
 public:
-  EmitRegisterMatcher(Record *reg, MVT::SimpleValueType vt)
+  EmitRegisterMatcher(const CodeGenRegister *reg, MVT::SimpleValueType vt)
     : Matcher(EmitRegister), Reg(reg), VT(vt) {}
 
-  Record *getReg() const { return Reg; }
+  const CodeGenRegister *getReg() const { return Reg; }
   MVT::SimpleValueType getVT() const { return VT; }
 
   static inline bool classof(const Matcher *N) {

utils/TableGen/DAGISelMatcherEmitter.cpp

@@ -43,11 +43,9 @@ class MatcherTableEmitter {
   DenseMap<Record*, unsigned> NodeXFormMap;
   std::vector<Record*> NodeXForms;
 
-  bool useEmitRegister2;
-
 public:
-  MatcherTableEmitter(const CodeGenDAGPatterns &cgp, bool _useEmitRegister2)
-    : CGP(cgp), useEmitRegister2(_useEmitRegister2) {}
+  MatcherTableEmitter(const CodeGenDAGPatterns &cgp)
+    : CGP(cgp) {}
 
   unsigned EmitMatcherList(const Matcher *N, unsigned Indent,
                            unsigned StartIdx, formatted_raw_ostream &OS);
@@ -431,25 +429,20 @@ EmitMatcher(const Matcher *N, unsigned Indent, unsigned CurrentIdx,
     return 3;
   }
 
-  case Matcher::EmitRegister:
-    if (useEmitRegister2) {
-      OS << "OPC_EmitRegister2, "
-        << getEnumName(cast<EmitRegisterMatcher>(N)->getVT()) << ", ";
-      if (Record *R = cast<EmitRegisterMatcher>(N)->getReg())
-        OS << "TARGET_VAL(" << getQualifiedName(R) << "),\n";
-      else {
-        OS << "TARGET_VAL(0) ";
-        if (!OmitComments)
-          OS << "/*zero_reg*/";
-        OS << ",\n";
-      }
+  case Matcher::EmitRegister: {
+    const EmitRegisterMatcher *Matcher = cast<EmitRegisterMatcher>(N);
+    const CodeGenRegister *Reg = Matcher->getReg();
+    // If the enum value of the register is larger than one byte can handle,
+    // use EmitRegister2.
+    if (Reg && Reg->EnumValue > 255) {
+      OS << "OPC_EmitRegister2, " << getEnumName(Matcher->getVT()) << ", ";
+      OS << "TARGET_VAL(" << getQualifiedName(Reg->TheDef) << "),\n";
       return 4;
     } else {
-      OS << "OPC_EmitRegister, "
-        << getEnumName(cast<EmitRegisterMatcher>(N)->getVT()) << ", ";
-      if (Record *R = cast<EmitRegisterMatcher>(N)->getReg())
-        OS << getQualifiedName(R) << ",\n";
-      else {
+      OS << "OPC_EmitRegister, " << getEnumName(Matcher->getVT()) << ", ";
+      if (Reg) {
+        OS << getQualifiedName(Reg->TheDef) << ",\n";
+      } else {
         OS << "0 ";
         if (!OmitComments)
           OS << "/*zero_reg*/";
@@ -457,6 +450,7 @@ EmitMatcher(const Matcher *N, unsigned Indent, unsigned CurrentIdx,
       }
       return 3;
     }
+  }
 
   case Matcher::EmitConvertToTarget:
     OS << "OPC_EmitConvertToTarget, "
@@ -800,14 +794,13 @@ void MatcherTableEmitter::EmitHistogram(const Matcher *M,
 
 void llvm::EmitMatcherTable(const Matcher *TheMatcher,
                             const CodeGenDAGPatterns &CGP,
-                            bool useEmitRegister2,
                             raw_ostream &O) {
   formatted_raw_ostream OS(O);
 
   OS << "// The main instruction selector code.\n";
   OS << "SDNode *SelectCode(SDNode *N) {\n";
 
-  MatcherTableEmitter MatcherEmitter(CGP, useEmitRegister2);
+  MatcherTableEmitter MatcherEmitter(CGP);
 
   OS << "  // Some target values are emitted as 2 bytes, TARGET_VAL handles\n";
   OS << "  // this.\n";

utils/TableGen/DAGISelMatcherGen.cpp

@@ -9,7 +9,9 @@
 
 #include "DAGISelMatcher.h"
 #include "CodeGenDAGPatterns.h"
+#include "CodeGenRegisters.h"
 #include "Record.h"
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringMap.h"
 #include <utility>
@@ -91,6 +93,10 @@ namespace {
     /// CurPredicate - As we emit matcher nodes, this points to the latest check
     /// which should have future checks stuck into its Next position.
     Matcher *CurPredicate;
+
+    /// RegisterDefMap - A map of register record definitions to the
+    /// corresponding target CodeGenRegister entry.
+    DenseMap<const Record *, const CodeGenRegister *> RegisterDefMap;
   public:
     MatcherGen(const PatternToMatch &pattern, const CodeGenDAGPatterns &cgp);
 
@@ -159,6 +165,12 @@ MatcherGen::MatcherGen(const PatternToMatch &pattern,
 
   // If there are types that are manifestly known, infer them.
   InferPossibleTypes();
+
+  // Populate the map from records to CodeGenRegister entries.
+  const CodeGenTarget &CGT = CGP.getTargetInfo();
+  const std::vector<CodeGenRegister> &Registers = CGT.getRegisters();
+  for (unsigned i = 0, e = Registers.size(); i != e; ++i)
+    RegisterDefMap[Registers[i].TheDef] = &Registers[i];
 }
 
 /// InferPossibleTypes - As we emit the pattern, we end up generating type
@@ -578,7 +590,8 @@ void MatcherGen::EmitResultLeafAsOperand(const TreePatternNode *N,
   // If this is an explicit register reference, handle it.
   if (DefInit *DI = dynamic_cast<DefInit*>(N->getLeafValue())) {
     if (DI->getDef()->isSubClassOf("Register")) {
-      AddMatcher(new EmitRegisterMatcher(DI->getDef(), N->getType(0)));
+      AddMatcher(new EmitRegisterMatcher(RegisterDefMap[DI->getDef()],
+                                         N->getType(0)));
       ResultOps.push_back(NextRecordedOperandNo++);
       return;
     }