[llvm-dev] MC Assembler / tablegen: actually parsing variable_ops

[Friedman, Eli via llvm-dev]

On 12/3/2018 5:32 PM, Wouter van Oortmerssen via llvm-dev wrote:
> variable_ops is used in the tablegen defs for many targets to denote 
> instructions that a variable number of inputs, but it seems that there 
> aren't any targets for which this results in variable elements in the 
> instruction encoding (and thus in assembler parsing), since the 
> tablegen generated assembly matcher ($(Target)GenAsmMatcher.inc) 
> simply assumes that variable_ops are not to be parsed (match table: 
> Convert_NoOperands).

ARM has ldm/stm, which take a variable number of register operands.  You 
might want to look at how ARMInstrInfo.td uses a "reglist" operand to 
represent the list of registers.

-Eli

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