[LLVMdev] Getting MCInst "ins" and "outs"

Christoph Grenz christophg+llvm at grenz-bonn.de
Wed Dec 26 08:53:05 PST 2012


Am Mittwoch, 26. Dezember 2012, 15:20:27 schrieb Manny Ko:
> The MCInstrDesc has a method getNumDefs() which tells you how many 'out
> registers' that MCInst has. The 'out' registers are always at the beginning
> of the list.  You can also use getNumOperands().

I've run into the problem, that this doesn't work for instructions which have 
variadic arguments like Push and Pop on ARM/Thumb. There is currently no way 
to tell if the registers beginning with getNumOperands()-2 are 'ins' or 

> Not sure if this is what you are looking for.
> -----Original Message-----
> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
> Behalf Of Vladimir Pouzanov Sent: Sunday, December 23, 2012 3:35 PM
> To: llvmdev at cs.uiuc.edu
> Subject: [LLVMdev] Getting MCInst "ins" and "outs"
> [...]
> Now, what are the two last operands (that are not actually present in
> disassembly)? And is it somehow possible to map the operands to
> OutOperandList/InOperandList found in the td definition?

I don't know about your specific case, but these are often flags (for 
conditional execution, addressing specification etc.). They might show as 
suffixes on the instruction name in the assembly.

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