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
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278788
91177308-0d34-0410-b5e6-
96231b3b80d8
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:
// Offset by 4, and don't encode the low two bits.
return ((Value - 4) >> 2) & 0xff;
case ARM::fixup_arm_thumb_cb: {
+ // CB instructions can only branch to offsets in [0, 126] in multiples of 2
+ if (Ctx && ((int64_t)Value < 0 || Value > 0x3e || Value & 1)) {
+ Ctx->reportError(Fixup.getLoc(), "out of range pc-relative fixup value");
+ return 0;
+ }
// Offset by 4 and don't encode the lower bit, which is always 0.
// FIXME: diagnose if no Thumb2
uint32_t Binary = (Value - 4) >> 1;
--- /dev/null
+@ RUN: not llvm-mc -triple thumbv7m-none-eabi -filetype=obj -o /dev/null %s 2>&1 | FileCheck %s
+@ RUN: not llvm-mc -triple thumbv8m.base-none-eabi -filetype=obj -o /dev/null %s 2>&1 | FileCheck %s
+
+label0:
+ .word 4
+
+@ CHECK: out of range pc-relative fixup value
+ cbz r0, label0
+@ CHECK: out of range pc-relative fixup value
+ cbnz r0, label0
+
+@ CHECK: out of range pc-relative fixup value
+ cbz r0, label1
+@ CHECK: out of range pc-relative fixup value
+ cbnz r0, label1
+
+ .space 1000
+label1:
+ .word 4
@ CHECK-ERRORS: error: branch target out of range
@------------------------------------------------------------------------------
+@ CBZ/CBNZ - out of range immediates for branches
+@------------------------------------------------------------------------------
+
+ cbz r0, #-2
+ cbz r0, #0
+ cbz r0, #17
+ cbnz r0, #126
+ cbnz r0, #128
+
+@ CHECK-ERRORS-V7M: error: branch target out of range
+@ CHECK-ERRORS-V7M: error: invalid operand for instruction
+@ CHECK-ERRORS-V7M: error: branch target out of range
+@ CHECK-ERRORS-V8: error: branch target out of range
+@ CHECK-ERRORS-V8: error: invalid operand for instruction
+@ CHECK-ERRORS-V8: error: branch target out of range
+
+@------------------------------------------------------------------------------
@ SEV/WFE/WFI/YIELD - are not supported pre v6M or v6T2
@------------------------------------------------------------------------------
sev