Enable on-demand fast-isel.

llvm-svn: 107377

2 files changed, 10 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index cc8c3c70ac2..2d6b78840f5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -161,7 +161,10 @@ unsigned FastISel::materializeRegForValue(const Value *V, MVT VT) {
       }
     }
   } 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/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 3b0ef18dd85..0848e46c0ef 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -709,6 +709,12 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
       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;