[LLVMdev] The type or size of virtual registers in machineinstr

[Jakob Stoklund Olesen]

On Jan 28, 2011, at 6:34 PM, Qingan Li wrote:

> I want to know what is the type or size of a virtual register in a Machineinstr::MachineOperand (If this MachineOperand is a register). For example, what is the size of reg16385 in the following MachineInstr. I know now in the llvm bitcode, the type of a Instruction could be obtained from the Value::GetType(), but what is the counterpart in MachineInstr (not derived from class Value)? 
> 
>  %reg16385<def> = MOV32rm <fi#0>, 1, %reg0, 0, %reg0; mem:LD4[%x_addr] GR32:%reg16385

There are no types in machine code, that is not tracked by the code generator.

The size of a register is not completely well defined (think of x87), but TargetRegisterClass::getSize() will tell you the size of the spill slot that the register allocator would use for the register.

/jakob

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