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X86: Call __main using the SelectionDAG

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Synthesizing a call directly using the MI layer would confuse the frame
lowering code.  This is problematic as frame lowering is highly
sensitive the particularities of calls, etc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230129 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2015-02-21 05:49:45 +00:00
parent 5872174fd8
commit 164db1c6b9
2 changed files with 13 additions and 10 deletions
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1
lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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@ -7884,7 +7884,6 @@ void SelectionDAGISel::LowerArguments(const Function &F) {
assert(i == InVals.size() && "Argument register count mismatch!");
// Finally, if the target has anything special to do, allow it to do so.
// FIXME: this should insert code into the DAG!
EmitFunctionEntryCode();
}

22
lib/Target/X86/X86ISelDAGToDAG.cpp
View File

@ -231,7 +231,7 @@ namespace {
char ConstraintCode,
std::vector<SDValue> &OutOps) override;
void EmitSpecialCodeForMain(MachineBasicBlock *BB, MachineFrameInfo *MFI);
void EmitSpecialCodeForMain();
inline void getAddressOperands(X86ISelAddressMode &AM, SDValue &Base,
SDValue &Scale, SDValue &Index,
@ -565,14 +565,18 @@ void X86DAGToDAGISel::PreprocessISelDAG() {
/// EmitSpecialCodeForMain - Emit any code that needs to be executed only in
/// the main function.
void X86DAGToDAGISel::EmitSpecialCodeForMain(MachineBasicBlock *BB,
MachineFrameInfo *MFI) {
const TargetInstrInfo *TII = getInstrInfo();
void X86DAGToDAGISel::EmitSpecialCodeForMain() {
if (Subtarget->isTargetCygMing()) {
unsigned CallOp =
Subtarget->is64Bit() ? X86::CALL64pcrel32 : X86::CALLpcrel32;
BuildMI(BB, DebugLoc(),
TII->get(CallOp)).addExternalSymbol("__main");
TargetLowering::ArgListTy Args;
TargetLowering::CallLoweringInfo CLI(*CurDAG);
CLI.setChain(CurDAG->getRoot())
.setCallee(CallingConv::C, Type::getVoidTy(*CurDAG->getContext()),
CurDAG->getExternalSymbol("__main", TLI->getPointerTy()),
std::move(Args), 0);
const TargetLowering &TLI = CurDAG->getTargetLoweringInfo();
std::pair<SDValue, SDValue> Result = TLI.LowerCallTo(CLI);
CurDAG->setRoot(Result.second);
}
}
@ -580,7 +584,7 @@ void X86DAGToDAGISel::EmitFunctionEntryCode() {
// If this is main, emit special code for main.
if (const Function *Fn = MF->getFunction())
if (Fn->hasExternalLinkage() && Fn->getName() == "main")
EmitSpecialCodeForMain(MF->begin(), MF->getFrameInfo());
EmitSpecialCodeForMain();
}
static bool isDispSafeForFrameIndex(int64_t Val) {