Basic block combine pass

Combine basic blocks terminated by instruction that we have since
proven not to throw.  This change is intended to relieve some of the
computational load for llvm by reducing the number of basic blocks
it has to contend with.

Also:
  Add stats to show how successful check elimination is.
  Restore mechanism to disable some expensive optimization passes when
  compiling large methods.

Change-Id: I7fae22160988cbefb90ea9fb1cc26d7364e8d229
diff --git a/src/compiler/codegen/MethodBitcode.cc b/src/compiler/codegen/MethodBitcode.cc
index cfe6e6a..8d62750 100644
--- a/src/compiler/codegen/MethodBitcode.cc
+++ b/src/compiler/codegen/MethodBitcode.cc
@@ -1668,8 +1668,11 @@
         DCHECK_EQ(rlDest.fp, loc.fp);
         DCHECK_EQ(rlDest.core, loc.core);
         DCHECK_EQ(rlDest.ref, loc.ref);
+        SafeMap<unsigned int, unsigned int>::iterator it;
+        it = cUnit->blockIdMap.find(incoming[i]);
+        DCHECK(it != cUnit->blockIdMap.end());
         phi->addIncoming(getLLVMValue(cUnit, loc.origSReg),
-                         getLLVMBlock(cUnit, incoming[i]));
+                         getLLVMBlock(cUnit, it->second));
       }
       defineValue(cUnit, phi, rlDest.origSReg);
       break;
@@ -1752,6 +1755,7 @@
 /* Handle the content in each basic block */
 bool methodBlockBitcodeConversion(CompilationUnit* cUnit, BasicBlock* bb)
 {
+  if (bb->blockType == kDead) return false;
   llvm::BasicBlock* llvmBB = getLLVMBlock(cUnit, bb->id);
   cUnit->irb->SetInsertPoint(llvmBB);
   setDexOffset(cUnit, bb->startOffset);
@@ -1964,7 +1968,7 @@
 bool createLLVMBasicBlock(CompilationUnit* cUnit, BasicBlock* bb)
 {
   // Skip the exit block
-  if (bb->blockType == kExitBlock) {
+  if ((bb->blockType == kDead) ||(bb->blockType == kExitBlock)) {
     cUnit->idToBlockMap.Put(bb->id, NULL);
   } else {
     int offset = bb->startOffset;
@@ -2924,11 +2928,8 @@
     cUnit->liveSReg = INVALID_SREG;
 #endif
 
-    LIR* boundaryLIR;
-    const char* instStr = "boundary";
-    boundaryLIR = newLIR1(cUnit, kPseudoDalvikByteCodeBoundary,
-                          (intptr_t) instStr);
-    cUnit->boundaryMap.Overwrite(cUnit->currentDalvikOffset, boundaryLIR);
+    // TODO: use llvm opcode name here instead of "boundary" if verbose
+    LIR* boundaryLIR = markBoundary(cUnit, cUnit->currentDalvikOffset, "boundary");
 
     /* Remember the first LIR for thisl block*/
     if (headLIR == NULL) {