search for: mthi

What I didn't mention in r192119 is that mthi/lo clobbers the other sub-register only if the contents of hi and lo are produced by mult or other arithmetic instructions (div, madd, etc.) It doesn't have this side-effect if it is produced by another mthi/lo. So I don't think making mthi/lo clobber the other half would work. For example...

On Oct 8, 2013, at 2:06 PM, Akira Hatanaka <ahatanak at gmail.com> wrote: > What I didn't mention in r192119 is that mthi/lo clobbers the other sub-register only if the contents of hi and lo are produced by mult or other arithmetic instructions (div, madd, etc.) It doesn't have this side-effect if it is produced by another mthi/lo. So I don't think making mthi/lo clobber the other half would work. Uh that is i...

Currently it will always spill / restore the whole vreg but only spilling the parts that are actually live would be a nice addition in the future. Looking at r192119': if "mtlo" writes to $LO and sets $HI to an unpredictable value, then it should just have an additional (dead) def operand for $hi, shouldn't it? Greetings Matthias Am 10/8/13, 11:03 AM, schrieb Akira

...expansion: The following pseudo LoadAC $acc, FI // Pseudo load instructions. Load from FI to accumulator $acc. is expanded into this sequence: LW $reg, FI // load from FI to temporary GPR $reg MTLO $reg // copy $reg to register LO LW $reg, FI + 4 // load from FI+4 to GPR $reg MTHI $reg // copy $reg to register HI -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20130325/d05b1990/attachment.html> -------------- next part -------------- A non-text attachment was scrubbed... Name...

...$acc, FI // Pseudo load instructions. Load from FI to accumulator $acc. > > > is expanded into this sequence: > > LW $reg, FI // load from FI to temporary GPR $reg > MTLO $reg // copy $reg to register LO > LW $reg, FI + 4 // load from FI+4 to GPR $reg > MTHI $reg // copy $reg to register HI Hi Akira, The register scavenger is not really supposed to be used in more than one pass, because you would need to allocate a separate emergency spill slot for each pass. I think Hal is trying to solve a very similar problem for PPC. Hal, are you expan...

...d from FI to accumulator > $acc. > > > > > > is expanded into this sequence: > > > > LW $reg, FI // load from FI to temporary GPR $reg > > MTLO $reg // copy $reg to register LO > > LW $reg, FI + 4 // load from FI+4 to GPR $reg > > MTHI $reg // copy $reg to register HI > > Hi Akira, > > The register scavenger is not really supposed to be used in more than one > pass, because you would need to allocate a separate emergency spill slot > for each pass. > > I think Hal is trying to solve a very similar...