Enable on-demand fast-isel.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107377 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index cc8c3c7..2d6b788 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -161,7 +161,10 @@
       }
     }
   } else if (const Operator *Op = dyn_cast<Operator>(V)) {
-    if (!SelectOperator(Op, Op->getOpcode())) return 0;
+    if (!SelectOperator(Op, Op->getOpcode()))
+      if (!isa<Instruction>(Op) ||
+          !TargetSelectInstruction(cast<Instruction>(Op)))
+        return 0;
     Reg = lookUpRegForValue(Op);
   } else if (isa<UndefValue>(V)) {
     Reg = createResultReg(TLI.getRegClassFor(VT));
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 3b0ef18..0848e46 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -709,6 +709,12 @@
       FastIS->startNewBlock(BB);
       // Do FastISel on as many instructions as possible.
       for (; BI != End; ++BI) {
+        // Defer instructions with no side effects; they'll be emitted
+        // on-demand later.
+        if (BI->isSafeToSpeculativelyExecute() &&
+            !FuncInfo->ValueMap.count(BI))
+          continue;
+
         // Try to select the instruction with FastISel.
         if (FastIS->SelectInstruction(BI))
           continue;