[Thumb] Validate branch target for CBZ/CBNZ instructions.
Summary:
The assembler currently does not check the branch target for CBZ/CBNZ
instructions, which only permit branching forwards with a positive offset. This
adds validation for the branch target to ensure negative PC-relative offsets are
not encoded into the instruction, whether specified as a literal or as an
assembler symbol.
Reviewers: rengolin, t.p.northover
Subscribers: llvm-commits, rengolin
Differential Revision: https://reviews.llvm.org/D23312
llvm-svn: 278788
diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index b9b665f..c011c79 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -6684,6 +6684,12 @@
return Error(Operands[Op]->getStartLoc(), "branch target out of range");
break;
}
+ case ARM::tCBZ:
+ case ARM::tCBNZ: {
+ if (!static_cast<ARMOperand &>(*Operands[2]).isUnsignedOffset<6, 1>())
+ return Error(Operands[2]->getStartLoc(), "branch target out of range");
+ break;
+ }
case ARM::MOVi16:
case ARM::t2MOVi16:
case ARM::t2MOVTi16: