Hi Andrew, > On 07/25/2012 12:15 PM, Jon Beniston wrote: > > For MIPS and LM32, truncation is performed in the calling function and > > sign extension in the called function. One of these operations seems > > redundant. For ARM, truncation is performed in the caller, but > > sign-extension isn't performed in the callee, which seems more > > efficient. Why might this be? > > This is defined by the system ABI, which specifies when zero- or sign- > extension get done. The ARM ABI explicitly requires a caller to extend types > appropriately before they are passed, and a callee can depend on that. We > in GCC have to follow the rules, and we can take advantage of them. > > I suspect the answer to your question will be found in the ABIs of the MIPS > and LM32, but I'm not familiar with either of those.
In the LM32 case, this is something that was overlooked, so it isn't that way because that's how it is required. I guess my question is what would I need to change to make it work like the ARM port? I can't see how this is being controlled. Thanks, Jon
