[JITLink][AARCH64] Fix overflow range of Page21

[sunho]

Summary

Allowed range for Page21 relocation is -2^32 <= X < 2^32 in both ELF and MachO.

https://github.com/llvm/llvm-project/blob/09c2b7c35af8c4bad39f03e9f60df8bd07323028/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOAArch64.h#L210 (MachO)

ELF for the ARM ® 64-bit Architecture (AArch64) Table 4-9 (ELF)

[sunho]

In ELF there's "no overflow check" relocations entries. (for page21, it's R_AARCH64_ ADR_PREL_PG_HI21_NC) Something to be considered later.

[sgraenitz]

Good catch!

[sunho]

Rebase on updated generic aarch64 fixup patch.

llvm/include/llvm/ExecutionEngine/JITLink/aarch64.h

assert((E.getKind() != GOTPage21 || E.getAddend() == 0) &&
            "GOTPAGE21 with non-zero addend");
     uint64_t TargetPage =
         (E.getTarget().getAddress().getValue() + E.getAddend()) &
         ~static_cast<uint64_t>(4096 - 1);
     uint64_t PCPage =
         FixupAddress.getValue() & ~static_cast<uint64_t>(4096 - 1);
 
     int64_t PageDelta = TargetPage - PCPage;
-    if (PageDelta < -(1 << 30) || PageDelta > ((1 << 30) - 1))
+    if (!isInt<33>(PageDelta))
       return makeTargetOutOfRangeError(G, B, E);
 
     uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
     assert((RawInstr & 0xffffffe0) == 0x90000000 &&
            "RawInstr isn't an ADRP instruction");
     uint32_t ImmLo = (static_cast<uint64_t>(PageDelta) >> 12) & 0x3;
     uint32_t ImmHi = (static_cast<uint64_t>(PageDelta) >> 14) & 0x7ffff;
     uint32_t FixedInstr = RawInstr | (ImmLo << 29) | (ImmHi << 5);