Add "first class" lowering for deopt operand bundles

Summary:
After this change, deopt operand bundles can be lowered directly by
SelectionDAG into STATEPOINT instructions (which are then lowered to a
call or sequence of nop, with an associated __llvm_stackmaps entry0.
This obviates the need to round-trip deoptimization state through
gc.statepoint via RewriteStatepointsForGC.

Reviewers: reames, atrick, majnemer, JosephTremoulet, pgavlin

Subscribers: sanjoy, mcrosier, majnemer, llvm-commits

Differential Revision: http://reviews.llvm.org/D18257

llvm-svn: 264015

1 files changed, 33 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 3e4111e8027..d01dd983324 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2127,6 +2127,15 @@ void SelectionDAGBuilder::visitInvoke(const InvokeInst &I) {
   MachineBasicBlock *Return = FuncInfo.MBBMap[I.getSuccessor(0)];
   const BasicBlock *EHPadBB = I.getSuccessor(1);
 
+#ifndef NDEBUG
+  // Deopt bundles are lowered in LowerCallSiteWithDeoptBundle, and we don't
+  // have to do anything here to lower funclet bundles.
+  for (unsigned i = 0, e = I.getNumOperandBundles(); i != e; ++i)
+    assert((I.getOperandBundleAt(i).isDeoptOperandBundle() ||
+            I.getOperandBundleAt(i).isFuncletOperandBundle()) &&
+           "Cannot lower invokes with arbitrary operand bundles yet!");
+#endif
+
   const Value *Callee(I.getCalledValue());
   const Function *Fn = dyn_cast<Function>(Callee);
   if (isa<InlineAsm>(Callee))
@@ -2146,8 +2155,15 @@ void SelectionDAGBuilder::visitInvoke(const InvokeInst &I) {
       LowerStatepoint(ImmutableStatepoint(&I), EHPadBB);
       break;
     }
-  } else
+  } else if (I.countOperandBundlesOfType(LLVMContext::OB_deopt)) {
+    // Currently we do not lower any intrinsic calls with deopt operand bundles.
+    // Eventually we will support lowering the @llvm.experimental.deoptimize
+    // intrinsic, and right now there are no plans to support other intrinsics
+    // with deopt state.
+    LowerCallSiteWithDeoptBundle(&I, getValue(Callee), EHPadBB);
+  } else {
     LowerCallTo(&I, getValue(Callee), false, EHPadBB);
+  }
 
   // If the value of the invoke is used outside of its defining block, make it
   // available as a virtual register.
@@ -6100,9 +6116,22 @@ void SelectionDAGBuilder::visitCall(const CallInst &I) {
         RenameFn,
         DAG.getTargetLoweringInfo().getPointerTy(DAG.getDataLayout()));
 
-  // Check if we can potentially perform a tail call. More detailed checking is
-  // be done within LowerCallTo, after more information about the call is known.
-  LowerCallTo(&I, Callee, I.isTailCall());
+#ifndef NDEBUG
+  // Deopt bundles are lowered in LowerCallSiteWithDeoptBundle, and we don't
+  // have to do anything here to lower funclet bundles.
+  for (unsigned i = 0, e = I.getNumOperandBundles(); i != e; ++i)
+    assert((I.getOperandBundleAt(i).isDeoptOperandBundle() ||
+            I.getOperandBundleAt(i).isFuncletOperandBundle()) &&
+           "Cannot lower calls with arbitrary operand bundles!");
+#endif
+
+  if (I.countOperandBundlesOfType(LLVMContext::OB_deopt))
+    LowerCallSiteWithDeoptBundle(&I, Callee, nullptr);
+  else
+    // Check if we can potentially perform a tail call. More detailed checking
+    // is be done within LowerCallTo, after more information about the call is
+    // known.
+    LowerCallTo(&I, Callee, I.isTailCall());
 }
 
 namespace {