[RISCV] Fix crash in decoding instruction with unknown floating point rounding mode
Summary:
Instead of crashing in printFRMArg, decode and warn about invalid instruction.
This bug was uncovered by a LLVM MC Disassembler Protocol Buffer Fuzzer
for the RISC-V assembly language.
Reviewers: asb
Reviewed By: asb
Subscribers: rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, mgrang, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, asb
Differential Revision: https://reviews.llvm.org/D51705
llvm-svn: 341691
diff --git a/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp b/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
index a2a6ffc..69afa4b 100644
--- a/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
+++ b/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
@@ -11,6 +11,7 @@
//
//===----------------------------------------------------------------------===//
+#include "MCTargetDesc/RISCVBaseInfo.h"
#include "MCTargetDesc/RISCVMCTargetDesc.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDisassembler/MCDisassembler.h"
@@ -243,6 +244,17 @@
return MCDisassembler::Success;
}
+static DecodeStatus decodeFRMArg(MCInst &Inst, uint64_t Imm,
+ int64_t Address,
+ const void *Decoder) {
+ assert(isUInt<3>(Imm) && "Invalid immediate");
+ if (!llvm::RISCVFPRndMode::isValidRoundingMode(Imm))
+ return MCDisassembler::Fail;
+
+ Inst.addOperand(MCOperand::createImm(Imm));
+ return MCDisassembler::Success;
+}
+
#include "RISCVGenDisassemblerTables.inc"
DecodeStatus RISCVDisassembler::getInstruction(MCInst &MI, uint64_t &Size,