[RISCV] Add support for _interrupt attribute
- Save/restore only registers that are used.
This includes Callee saved registers and Caller saved registers
(arguments and temporaries) for integer and FP registers.
- If there is a call in the interrupt handler, save/restore all
Caller saved registers (arguments and temporaries) and all FP registers.
- Emit special return instructions depending on "interrupt"
attribute type.
Based on initial patch by Zhaoshi Zheng.
Reviewers: asb
Reviewed By: asb
Subscribers: rkruppe, the_o, MartinMosbeck, brucehoult, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, mgrang, rogfer01, llvm-commits
Differential Revision: https://reviews.llvm.org/D48411
llvm-svn: 338047
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index dda26a7..87796e5 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -967,6 +967,21 @@
}
MachineFunction &MF = DAG.getMachineFunction();
+
+ const Function &Func = MF.getFunction();
+ if (Func.hasFnAttribute("interrupt")) {
+ if (!Func.arg_empty())
+ report_fatal_error(
+ "Functions with the interrupt attribute cannot have arguments!");
+
+ StringRef Kind =
+ MF.getFunction().getFnAttribute("interrupt").getValueAsString();
+
+ if (!(Kind == "user" || Kind == "supervisor" || Kind == "machine"))
+ report_fatal_error(
+ "Function interrupt attribute argument not supported!");
+ }
+
EVT PtrVT = getPointerTy(DAG.getDataLayout());
MVT XLenVT = Subtarget.getXLenVT();
unsigned XLenInBytes = Subtarget.getXLen() / 8;
@@ -1515,6 +1530,28 @@
RetOps.push_back(Glue);
}
+ // Interrupt service routines use different return instructions.
+ const Function &Func = DAG.getMachineFunction().getFunction();
+ if (Func.hasFnAttribute("interrupt")) {
+ if (!Func.getReturnType()->isVoidTy())
+ report_fatal_error(
+ "Functions with the interrupt attribute must have void return type!");
+
+ MachineFunction &MF = DAG.getMachineFunction();
+ StringRef Kind =
+ MF.getFunction().getFnAttribute("interrupt").getValueAsString();
+
+ unsigned RetOpc;
+ if (Kind == "user")
+ RetOpc = RISCVISD::URET_FLAG;
+ else if (Kind == "supervisor")
+ RetOpc = RISCVISD::SRET_FLAG;
+ else
+ RetOpc = RISCVISD::MRET_FLAG;
+
+ return DAG.getNode(RetOpc, DL, MVT::Other, RetOps);
+ }
+
return DAG.getNode(RISCVISD::RET_FLAG, DL, MVT::Other, RetOps);
}
@@ -1524,6 +1561,12 @@
break;
case RISCVISD::RET_FLAG:
return "RISCVISD::RET_FLAG";
+ case RISCVISD::URET_FLAG:
+ return "RISCVISD::URET_FLAG";
+ case RISCVISD::SRET_FLAG:
+ return "RISCVISD::SRET_FLAG";
+ case RISCVISD::MRET_FLAG:
+ return "RISCVISD::MRET_FLAG";
case RISCVISD::CALL:
return "RISCVISD::CALL";
case RISCVISD::SELECT_CC: