[llvm] [RISC-V] Use an optional offset operand instead of zero-offset InstAliases (PR #210901)

[Alexander Richardson via llvm-commits]

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@@ -79,9 +79,7 @@ lw a0, -2049(a3)
 lw a0, -2049(f0)
 # CHECK: :[[@LINE-1]]:1: error: invalid instruction, any one of the following would fix this:
 # CHECK: :[[@LINE-2]]:8: note: operand must be a bare symbol name
-# CHECK: :[[@LINE-3]]:8: note: expected '('
-# CHECK: :[[@LINE-4]]:8: note: operand must be a symbol with %lo/%pcrel_lo/%tprel_lo specifier or an integer in the range [-2048, 2047]
-# CHECK: :[[@LINE-5]]:8: note: immediate must be an integer in the range [-2048, 2047]
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arichardson wrote:

I feel like this one would actually be good to keep, but I guess the others have priority and it doesn't really matter when there are multiple errors. If it's the only error we still get a sensible diagnostic.

https://github.com/llvm/llvm-project/pull/210901