This patch substantially simplifies and cleans up handling of basic blocks

in the bytecode parser.  Before we tried to shoehorn basic blocks into the
"getValue" code path with other types of values.  For a variety of reasons
this was a bad idea, so this patch separates it out into its own data structure.

This simplifies the code, makes it fit in 80 columns, and is also much faster.
In a testcase provided by Bill, which has lots of PHI nodes, this patch speeds
up bytecode parsing from taking 6.9s to taking 2.32s.  More speedups to
follow later.

llvm-svn: 8977

1 files changed, 17 insertions, 20 deletions

diff --git a/llvm/lib/Bytecode/Reader/InstructionReader.cpp b/llvm/lib/Bytecode/Reader/InstructionReader.cpp
index d8a6af0179c..2f2e7960d60 100644
--- a/llvm/lib/Bytecode/Reader/InstructionReader.cpp
+++ b/llvm/lib/Bytecode/Reader/InstructionReader.cpp
@@ -161,12 +161,11 @@ bool BytecodeParser::ParseInstruction(const unsigned char *&Buf,
             delete PN; 
 	    return true;
     case 2: PN->addIncoming(getValue(Raw->Ty, Raw->Arg1),
-			    cast<BasicBlock>(getValue(Type::LabelTyID,
-                                                      Raw->Arg2)));
+                            getBasicBlock(Raw->Arg2));
       break;
     default:
-      PN->addIncoming(getValue(Raw->Ty, Raw->Arg1), 
-		      cast<BasicBlock>(getValue(Type::LabelTyID, Raw->Arg2)));
+      PN->addIncoming(getValue(Raw->Ty, Raw->Arg1),
+		      getBasicBlock(Raw->Arg2));
       if (Raw->VarArgs->size() & 1) {
 	std::cerr << "PHI Node with ODD number of arguments!\n";
 	delete PN;
@@ -174,8 +173,7 @@ bool BytecodeParser::ParseInstruction(const unsigned char *&Buf,
       } else {
         std::vector<unsigned> &args = *Raw->VarArgs;
         for (unsigned i = 0; i < args.size(); i+=2)
-          PN->addIncoming(getValue(Raw->Ty, args[i]),
-                       cast<BasicBlock>(getValue(Type::LabelTyID, args[i+1])));
+          PN->addIncoming(getValue(Raw->Ty, args[i]), getBasicBlock(args[i+1]));
       }
       delete Raw->VarArgs; 
       break;
@@ -200,20 +198,18 @@ bool BytecodeParser::ParseInstruction(const unsigned char *&Buf,
 
   case Instruction::Br:
     if (Raw->NumOperands == 1) {
-      Res = new BranchInst(cast<BasicBlock>(getValue(Type::LabelTyID,Raw->Arg1)));
+      Res = new BranchInst(getBasicBlock(Raw->Arg1));
       return false;
     } else if (Raw->NumOperands == 3) {
-      Res = new BranchInst(cast<BasicBlock>(getValue(Type::LabelTyID, Raw->Arg1)),
-			   cast<BasicBlock>(getValue(Type::LabelTyID, Raw->Arg2)),
-                                            getValue(Type::BoolTyID , Raw->Arg3));
+      Res = new BranchInst(getBasicBlock(Raw->Arg1), getBasicBlock(Raw->Arg2),
+                           getValue(Type::BoolTyID , Raw->Arg3));
       return false;
     }
     break;
     
   case Instruction::Switch: {
     SwitchInst *I = 
-      new SwitchInst(getValue(Raw->Ty, Raw->Arg1), 
-                     cast<BasicBlock>(getValue(Type::LabelTyID, Raw->Arg2)));
+      new SwitchInst(getValue(Raw->Ty, Raw->Arg1), getBasicBlock(Raw->Arg2));
     Res = I;
     if (Raw->NumOperands < 3) return false;  // No destinations?  Weird.
 
@@ -226,7 +222,7 @@ bool BytecodeParser::ParseInstruction(const unsigned char *&Buf,
     std::vector<unsigned> &args = *Raw->VarArgs;
     for (unsigned i = 0; i < args.size(); i += 2)
       I->addCase(cast<Constant>(getValue(Raw->Ty, args[i])),
-                 cast<BasicBlock>(getValue(Type::LabelTyID, args[i+1])));
+                 getBasicBlock(args[i+1]));
 
     delete Raw->VarArgs;
     return false;
@@ -311,11 +307,11 @@ bool BytecodeParser::ParseInstruction(const unsigned char *&Buf,
     if (!FTy->isVarArg()) {
       if (Raw->NumOperands < 3) return true;
 
-      Normal = cast<BasicBlock>(getValue(Type::LabelTyID, Raw->Arg2));
+      Normal = getBasicBlock(Raw->Arg2);
       if (Raw->NumOperands == 3)
-        Except = cast<BasicBlock>(getValue(Type::LabelTyID, Raw->Arg3));
+        Except = getBasicBlock(Raw->Arg3);
       else {
-        Except = cast<BasicBlock>(getValue(Type::LabelTyID, args[0]));
+        Except = getBasicBlock(args[0]);
 
         FunctionType::ParamTypes::const_iterator It = PL.begin();
         for (unsigned i = 1; i < args.size(); i++) {
@@ -327,10 +323,11 @@ bool BytecodeParser::ParseInstruction(const unsigned char *&Buf,
       }
     } else {
       if (args.size() < 4) return true;
-      if (getType(args[0]) != Type::LabelTy || 
-          getType(args[2]) != Type::LabelTy) return true;
-      Normal = cast<BasicBlock>(getValue(Type::LabelTyID, args[1]));
-      Except = cast<BasicBlock>(getValue(Type::LabelTyID, args[3]));
+      if (args[0] != Type::LabelTyID || args[2] != Type::LabelTyID)
+        return true;
+          
+      Normal = getBasicBlock(args[1]);
+      Except = getBasicBlock(args[3]);
 
       if ((args.size() & 1) != 0)
 	return true;  // Must be pairs of type/value