search for: sub_hi

...Hi, > > I have a question about the way sub-registers are spilled and restored > that is related to the changes I made in r192119. > > Suppose I have the following piece of code with four > instructions. %vreg0 and %vreg1 consist of two sub-registers indexed > by sub_lo and sub_hi. > > instr0 %vreg0<def> > instr1 %vreg1:sub_lo<def,read-undef> > instr2 %vreg0<use> > instr3 %vreg1:sub_hi<def> > > If register allocator decides to insert spill and restore instructions > for %vreg0, will it spill the whole register that includes &...

...Hi, > > I have a question about the way sub-registers are spilled and restored > that is related to the changes I made in r192119. > > Suppose I have the following piece of code with four > instructions. %vreg0 and %vreg1 consist of two sub-registers indexed by > sub_lo and sub_hi. > > instr0 %vreg0<def> > instr1 %vreg1:sub_lo<def,read-undef> > instr2 %vreg0<use> > instr3 %vreg1:sub_hi<def> > > If register allocator decides to insert spill and restore instructions > for %vreg0, will it spill the whole register that includes...

...Hi, >> >> I have a question about the way sub-registers are spilled and restored that is related to the changes I made in r192119. >> >> Suppose I have the following piece of code with four instructions. %vreg0 and %vreg1 consist of two sub-registers indexed by sub_lo and sub_hi. >> >> instr0 %vreg0<def> >> instr1 %vreg1:sub_lo<def,read-undef> >> instr2 %vreg0<use> >> instr3 %vreg1:sub_hi<def> >> >> If register allocator decides to insert spill and restore instructions for %vreg0, will it spill the whole r...

I've been working on patches to improve subregister liveness tracking on llvm and I wanted to inform the llvm community about the overal design/motivation for them. I will send the patches to llvm-commits later today. Greetings Matthias Braun Subregisters in llvm ==================== Some targets can access registers in different ways resulting in wider or narrower accesses. For

...up needing a lot of pseudo-nodes like EXTRACT_SUBREG whereas these are natural parts of the MIR syntax. For example: (set $d, (EXTRACT_SUBREG (MYTGT_ADD $A, $B), sub_lo)) compared to: %d:sub_lo = MYTGT_ADD %A, %B and: (set $d, (REG_SEQUENCE GPR32, (MYTGT_ADD $A, $B), sub_lo, (MYTGT_ADD $C, $D), sub_hi)) compared to: %d:sub_lo = MYTGT_ADD %A, %B %d:sub_hi = MYTGT_ADD %C, %D Along the same lines, I also think that the integrated debug-info is only really practical in MIR. It's possible to shoe-horn DILocation in using a pseudo-node like so: (set $d, (add (mul $a, $b):$mul, $c):$add -&g...

...RACT_SUBREG whereas these are natural parts of the MIR syntax. For example: >> (set $d, (EXTRACT_SUBREG (MYTGT_ADD $A, $B), sub_lo)) >> compared to: >> %d:sub_lo = MYTGT_ADD %A, %B >> and: >> (set $d, (REG_SEQUENCE GPR32, (MYTGT_ADD $A, $B), sub_lo, (MYTGT_ADD $C, $D), sub_hi)) >> compared to: >> %d:sub_lo = MYTGT_ADD %A, %B >> %d:sub_hi = MYTGT_ADD %C, %D > > How about: > > (MYTGT_ADD (sub_lo $d), $A, $B), > (MYTGT_ADD (sub_hi $d), $C, $D), > > That seems acceptable to me. That looks good to me too. >> Along the same...

Hi All, I've been working on the GlobalISel combiner recently and I'd like to share the plan for how Combine Rules will be defined in GlobalISel and solicit feedback on it. This email ended up rather long so: TL;DR: We're planning to define GlobalISel Combine Rules using MIR syntax with a few bits glued on to interface with the algorithm and escape into C++ when we need to.