[llvm] [ARMAsmBackend] Add checks for relocation addends in assembler (PR #109969)

[Oliver Stannard via llvm-commits]

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@@ -579,13 +579,24 @@ unsigned ARMAsmBackend::adjustFixupValue(const MCAssembler &Asm,
   case ARM::fixup_arm_uncondbl:
   case ARM::fixup_arm_condbl:
   case ARM::fixup_arm_blx:
+    // Check that the fixup value is legal.
+    Value = Value - 8;
+    if (!isInt<25>(Value)) {
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ostannard wrote:

Should this be `isInt<26>`? The ARM B/BL/BLX instructions take a 2's complement 24-bit immediate, left-shifted by 2.

https://github.com/llvm/llvm-project/pull/109969