[llvm] [M68k] add 32 bit branch instrs and relaxations (PR #117371)

[Kane York via llvm-commits]

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@@ -166,26 +225,35 @@ bool M68kAsmBackend::mayNeedRelaxation(const MCInst &Inst,
 }
 
 bool M68kAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup,
-                                          uint64_t Value) const {
-  // TODO Newer CPU can use 32 bit offsets, so check for this when ready
-  if (!isInt<16>(Value)) {
+                                          uint64_t UnsignedValue) const {
+  int64_t Value = static_cast<int64_t>(UnsignedValue);
+
+  if (!isInt<32>(Value) || (!Allows32BitBranch && !isInt<16>(Value)))
     llvm_unreachable("Cannot relax the instruction, value does not fit");
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riking wrote:

This probably should be a cleaner error than an unreachable? You can trip this easily by compiling 32-bit-okay code for a 16-bit-only device

https://github.com/llvm/llvm-project/pull/117371