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Re: Help restricting args of an intrinsic function

On Jan 30, 2004, at 5:42 PM, David Edelsohn wrote:

Ian Lance Taylor writes:

How do I collapse it down to a const_int?

Ian> You use a constraint of 'n'.

	The PowerPC port already provides special 'h' and 'H' constraints
for the 32-bit version and 64-bit instructions.

According to the internals manual:

An immediate integer operand with a known numeric value is allowed. Many systems cannot support assembly-time constants for operands less than a word wide. Constraints for these operands should use n rather than i.

h MQ, CTR, or LINK register

I am a complete beginner to gcc, so forgive my naive questions. But what is the difference between these two? h looks like it is a 32 bit value. n looks like a general assembly-constant less than one word wide. Since the assembly constants I need are 5 bits wide, it looks like n is the correct one to use.

Why would I use h?

Syd Polk
Apple Computer
Technology EPM, Mac OS X Development Tools
+1 408 974-0577

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