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Wouldn't things like "add x0, x1, x2" therefore better be at least warned about? 2) Insns like "beq x0, x0, ." (perhaps not very useful outside of assembler / disassembler test suites) result in odd ".L0 " labels in the object's symbol table. My best guess so far was that this may be a result of "#define tc_fix_adjustable(fixp) 0". As these labels are somewhat confusing - would there be a way to suppress their emission? 3) When the assembler can determine a branch's destination, e.g. in "beq x0, x0, .+1", wouldn't it be useful to warn about the non-even destination address? And with the C extension disabled even about any one not evenly divisible by 4? 4) A number of CSRs are valid in RV32 mode only. Shouldn't their use be diagnosed when assembling 64-bit code? (I thought I had seen a patch to this effect, but not overly old gas still happily accepts them.) 5) While possibly not too interesting for RV32, in RV64 auipc and lui have immediate operands which are sign-extended. Yet gas chokes on any of auipc x31, -0x100 lui x31, -0x100 c.lui x31, -0x20 Shouldn't signed operands be permitted (if not required) there, and then ideally permitted (but not required) also on RV32? Thanks for any helpful insight, Jan