search for: ctrrc

Displaying 4 results from an estimated 4 matches for "ctrrc".

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2012 Jun 08
0
[LLVMdev] Strong vs. default phi elimination and single-reg classes
...d read CTR in another). - Reserved registers can do whatever you want, but defs are treated as having side effects, blocking certain optimizations like dead code elimination. (You don't want to DCE a stack pointer update). In this case, the problem is that CTR and CTR8 are allocatable because CTRRC and CTRRC8 are allocatable. You can set 'isAllocatable = 0' in those register classes. Unfortunately, that breaks your TCRETURNri instructions. Sorry! Singleton register classes are dangerous because it is so easy to extend the live range of virtual registers without checking for interfer...
2012 Jun 08
2
[LLVMdev] Strong vs. default phi elimination and single-reg classes
...dk> wrote: > > On Jun 7, 2012, at 7:31 PM, Hal Finkel wrote: > > > 112B BB#1: derived from LLVM BB %for.body, ADDRESS TAKEN > > Predecessors according to CFG: BB#0 BB#1 > > %vreg12<def> = PHI %vreg13, <BB#1>, %vreg11, > > <BB#0>;CTRRC8:%vreg12,%vreg13,%vreg11 %vreg13<def> = COPY > > %vreg12<kill>; CTRRC8:%vreg13,%vreg12 %vreg13<def> = BDNZ8 %vreg13, > > <BB#1>; CTRRC8:%vreg13 B <BB#2> > > Successors according to CFG: BB#2 BB#1 > > > Phi-elim works by inserting...
2012 Jun 08
1
[LLVMdev] Strong vs. default phi elimination and single-reg classes
On Fri, 08 Jun 2012 09:24:16 -0700 Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote: > > On Jun 8, 2012, at 9:02 AM, Hal Finkel <hfinkel at anl.gov> wrote: > > > On Fri, 8 Jun 2012 08:49:32 -0700 > > Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote: > > >> When machine code is still in SSA form, there are restrictions on > >> what can
2012 Jun 08
2
[LLVMdev] Strong vs. default phi elimination and single-reg classes
...- Reserved registers can do whatever you want, but defs are treated > as having side effects, blocking certain optimizations like dead code > elimination. (You don't want to DCE a stack pointer update). > > In this case, the problem is that CTR and CTR8 are allocatable > because CTRRC and CTRRC8 are allocatable. You can set 'isAllocatable > = 0' in those register classes. Thanks for explaining! [We should add this to the docs somewhere]. > > Unfortunately, that breaks your TCRETURNri instructions. Sorry! I'm guessing that I can rewrite TCRETURN to refere...