[llvm] MCAsmBackend::applyFixup: Change `Data` to indicate the relocated location (PR #151724)

[Ulrich Weigand via llvm-commits]

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@@ -173,7 +171,7 @@ void SystemZMCAsmBackend::applyFixup(const MCFragment &F, const MCFixup &Fixup,
     Value &= ((uint64_t)1 << BitSize) - 1;
   unsigned ShiftValue = (Size * 8) - 8;
   for (unsigned I = 0; I != Size; ++I) {
-    Data[Offset + I] |= uint8_t(Value >> ShiftValue);
+    Data[I] |= uint8_t(Value >> ShiftValue);
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uweigand wrote:

It seems quite weird for this routine (a few lines above this) to compute `Offset` and assert on it being within a certain range, but then to never actually use it.  If common code handles the fixup offset, it should do so completely ...

https://github.com/llvm/llvm-project/pull/151724