[patchpoint] Add support for symbolic patchpoint targets to SelectionDAG and the

X86 backend.

The code generated for symbolic targets is identical to the code generated for
constant targets, except that a relocation is emitted to fix up the actual
target address at link-time. This allows IR and object files containing
patchpoints to be cached across JIT-invocations where the target address may
change.

llvm-svn: 235483

2 files changed, 27 insertions, 19 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index dafbc63dbd0..2b624adac94 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -711,7 +711,7 @@ bool FastISel::selectPatchpoint(const CallInst *I) {
   CallingConv::ID CC = I->getCallingConv();
   bool IsAnyRegCC = CC == CallingConv::AnyReg;
   bool HasDef = !I->getType()->isVoidTy();
-  Value *Callee = I->getOperand(PatchPointOpers::TargetPos);
+  Value *Callee = I->getOperand(PatchPointOpers::TargetPos)->stripPointerCasts();
 
   // Get the real number of arguments participating in the call <numArgs>
   assert(isa<ConstantInt>(I->getOperand(PatchPointOpers::NArgPos)) &&
@@ -757,23 +757,25 @@ bool FastISel::selectPatchpoint(const CallInst *I) {
       cast<ConstantInt>(I->getOperand(PatchPointOpers::NBytesPos));
   Ops.push_back(MachineOperand::CreateImm(NumBytes->getZExtValue()));
 
-  // Assume that the callee is a constant address or null pointer.
-  // FIXME: handle function symbols in the future.
-  uint64_t CalleeAddr;
-  if (const auto *C = dyn_cast<IntToPtrInst>(Callee))
-    CalleeAddr = cast<ConstantInt>(C->getOperand(0))->getZExtValue();
-  else if (const auto *C = dyn_cast<ConstantExpr>(Callee)) {
-    if (C->getOpcode() == Instruction::IntToPtr)
-      CalleeAddr = cast<ConstantInt>(C->getOperand(0))->getZExtValue();
-    else
+  // Add the call target.
+  if (const auto *C = dyn_cast<IntToPtrInst>(Callee)) {
+    uint64_t CalleeConstAddr =
+      cast<ConstantInt>(C->getOperand(0))->getZExtValue();
+    Ops.push_back(MachineOperand::CreateImm(CalleeConstAddr));
+  } else if (const auto *C = dyn_cast<ConstantExpr>(Callee)) {
+    if (C->getOpcode() == Instruction::IntToPtr) {
+      uint64_t CalleeConstAddr =
+        cast<ConstantInt>(C->getOperand(0))->getZExtValue();
+      Ops.push_back(MachineOperand::CreateImm(CalleeConstAddr));
+    } else
       llvm_unreachable("Unsupported ConstantExpr.");
+  } else if (const auto *GV = dyn_cast<GlobalValue>(Callee)) {
+    Ops.push_back(MachineOperand::CreateGA(GV, 0));
   } else if (isa<ConstantPointerNull>(Callee))
-    CalleeAddr = 0;
+    Ops.push_back(MachineOperand::CreateImm(0));
   else
     llvm_unreachable("Unsupported callee address.");
 
-  Ops.push_back(MachineOperand::CreateImm(CalleeAddr));
-
   // Adjust <numArgs> to account for any arguments that have been passed on
   // the stack instead.
   unsigned NumCallRegArgs = IsAnyRegCC ? NumArgs : CLI.OutRegs.size();
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 746a9efaa4d..2c813138f84 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7001,7 +7001,16 @@ void SelectionDAGBuilder::visitPatchpoint(ImmutableCallSite CS,
   CallingConv::ID CC = CS.getCallingConv();
   bool IsAnyRegCC = CC == CallingConv::AnyReg;
   bool HasDef = !CS->getType()->isVoidTy();
-  SDValue Callee = getValue(CS->getOperand(2)); // <target>
+  SDValue Callee = getValue(CS->getOperand(PatchPointOpers::TargetPos));
+
+  // Handle immediate and symbolic callees.
+  if (auto* ConstCallee = dyn_cast<ConstantSDNode>(Callee))
+    Callee = DAG.getIntPtrConstant(ConstCallee->getZExtValue(),
+                                   /*isTarget=*/true);
+  else if (auto* SymbolicCallee = dyn_cast<GlobalAddressSDNode>(Callee))
+    Callee =  DAG.getTargetGlobalAddress(SymbolicCallee->getGlobal(),
+                                         SDLoc(SymbolicCallee),
+                                         SymbolicCallee->getValueType(0));
 
   // Get the real number of arguments participating in the call <numArgs>
   SDValue NArgVal = getValue(CS.getArgument(PatchPointOpers::NArgPos));
@@ -7041,11 +7050,8 @@ void SelectionDAGBuilder::visitPatchpoint(ImmutableCallSite CS,
   Ops.push_back(DAG.getTargetConstant(
                   cast<ConstantSDNode>(NBytesVal)->getZExtValue(), MVT::i32));
 
-  // Assume that the Callee is a constant address.
-  // FIXME: handle function symbols in the future.
-  Ops.push_back(
-    DAG.getIntPtrConstant(cast<ConstantSDNode>(Callee)->getZExtValue(),
-                          /*isTarget=*/true));
+  // Add the callee.
+  Ops.push_back(Callee);
 
   // Adjust <numArgs> to account for any arguments that have been passed on the
   // stack instead.