Preliminary support for ARM frame save directives emission via MI flags.
This is just very first approximation how the stuff should be done
(e.g. ARM-only for now). More to follow.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127101 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMAsmPrinter.cpp b/lib/Target/ARM/ARMAsmPrinter.cpp
index 5ae3944..9285556 100644
--- a/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -811,6 +811,87 @@
OutStreamer.EmitInstruction(TmpInst);
}
+void ARMAsmPrinter::EmitUnwindingInstruction(const MachineInstr *MI) {
+ assert(MI->getFlag(MachineInstr::FrameSetup) &&
+ "Only instruction which are involved into frame setup code are allowed");
+
+ const MachineFunction &MF = *MI->getParent()->getParent();
+ const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
+
+ unsigned FramePtr = RegInfo->getFrameRegister(MF);
+ unsigned SrcReg = MI->getOperand(1).getReg();
+ unsigned DstReg = MI->getOperand(0).getReg();
+ unsigned Opc = MI->getOpcode();
+
+ // Try to figure out the unwinding opcode out of src / dst regs.
+ if (MI->getDesc().mayStore()) {
+ // Register saves.
+ assert(DstReg == ARM::SP &&
+ "Only stack pointer as a destination reg is supported");
+
+ SmallVector<unsigned, 4> RegList;
+ switch (Opc) {
+ default:
+ MI->dump();
+ assert(0 && "Unsupported opcode for unwinding information");
+ case ARM::STMDB_UPD:
+ case ARM::VSTMDDB_UPD:
+ assert(SrcReg == ARM::SP &&
+ "Only stack pointer as a source reg is supported");
+ for (unsigned i = 4, NumOps = MI->getNumOperands(); i != NumOps; ++i)
+ RegList.push_back(MI->getOperand(i).getReg());
+ break;
+ case ARM::STR_PRE:
+ assert(MI->getOperand(2).getReg() == ARM::SP &&
+ "Only stack pointer as a source reg is supported");
+ RegList.push_back(SrcReg);
+ break;
+ }
+ OutStreamer.EmitRegSave(RegList, Opc == ARM::VSTMDDB_UPD);
+ } else {
+ // Changes of stack / frame pointer.
+ if (SrcReg == ARM::SP) {
+ int64_t Offset = 0;
+ switch (Opc) {
+ default:
+ MI->dump();
+ assert(0 && "Unsupported opcode for unwinding information");
+ case ARM::MOVr:
+ Offset = 0;
+ break;
+ case ARM::ADDri:
+ Offset = -MI->getOperand(2).getImm();
+ break;
+ case ARM::SUBri:
+ Offset = MI->getOperand(2).getImm();
+ break;
+ }
+
+ if (DstReg == FramePtr && FramePtr != ARM::SP)
+ // Set-up of the frame pointer.
+ OutStreamer.EmitSetFP(FramePtr, ARM::SP, Offset);
+ else if (DstReg == ARM::SP) {
+ // Change of SP by an offset. Positive values corresponds to "sub"
+ // instruction.
+ OutStreamer.EmitPad(Offset);
+ } else {
+ MI->dump();
+ assert(0 && "Unsupported opcode for unwinding information");
+ }
+ } else if (DstReg == ARM::SP) {
+ // FIXME: .movsp goes here
+ MI->dump();
+ assert(0 && "Unsupported opcode for unwinding information");
+ }
+ else {
+ MI->dump();
+ assert(0 && "Unsupported opcode for unwinding information");
+ }
+ }
+}
+
+extern cl::opt<bool> EnableARMEHABI;
+
void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
unsigned Opc = MI->getOpcode();
switch (Opc) {
@@ -1564,6 +1645,11 @@
MCInst TmpInst;
LowerARMMachineInstrToMCInst(MI, TmpInst, *this);
+
+ // Emit unwinding stuff for frame-related instructions
+ if (EnableARMEHABI && MI->getFlag(MachineInstr::FrameSetup))
+ EmitUnwindingInstruction(MI);
+
OutStreamer.EmitInstruction(TmpInst);
}