Correct the upper bound for a CBZ/CBNZ branch target.
Summary:
Fix for the upper bound check that was causing a build failure.
Reviewers: olista01, rengolin, t.p.northover
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D23501
llvm-svn: 278789
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
index 5ac2d65..2c3214f 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -578,8 +578,10 @@
// 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)) {
+ // CB instructions can only branch to offsets in [4, 126] in multiples of 2
+ // so ensure that the raw value LSB is zero and it lies in [2, 130].
+ // An offset of 2 will be relaxed to a NOP.
+ if (Ctx && ((int64_t)Value < 2 || Value > 0x82 || Value & 1)) {
Ctx->reportError(Fixup.getLoc(), "out of range pc-relative fixup value");
return 0;
}