similar to: [LLVMdev] How to implement register allocation constraints to guide allocator dispatching different registers for certain instruction?

Hi Kevin, I concur Tim’s advice, you should use the @earlyclobber. Cheers, -Quentin On Feb 19, 2014, at 3:27 AM, Tim Northover <t.p.northover at gmail.com> wrote: > Hi Kevin, > >> I suppose to add some extra rules on register allocator to avoid it >> allocating register causing any unpredictable behavior, but I don't have >> experience to this part. Can

On Dec 15, 2009, at 5:08 PM, David Greene wrote: > On Tuesday 15 December 2009 18:01, Jim Grosbach wrote: > >> For a usage example, I've included in the patch the modification to >> use the constraint for the STREX ARM instruction. > > Your example is: > > constraints = "@early $success" > > Why not spell it as: > > constraints =

On Tuesday 15 December 2009 19:52, Jim Grosbach wrote: > Do you have specific examples in mind that would be expressible with > something more complicated that aren't handleable via an early-clobber > constraint? Not offhand, no. I'm mostly concerned about the readability of .td files. > Perhaps spelling it out more fully with "earlyclobber" rather than >

On Sep 21, 2010, at 2:45 PMPDT, John Thompson wrote: > fatal error: error in backend: Ran out of registers during register allocation! > Please check your inline asm statement for invalid constraints: > INLINEASM <es:>, 0, 10, %reg16396<def>, 10, %reg16397<def>, 10, %reg16398<def>, 10, %reg16399<def>, 10, %reg16400<def>, 10, %reg16401<def>,10,

On Dec 15, 2009, at 6:26 PM, David Greene wrote: > On Tuesday 15 December 2009 19:52, Jim Grosbach wrote: > >> Do you have specific examples in mind that would be expressible with >> something more complicated that aren't handleable via an early- >> clobber >> constraint? > > Not offhand, no. I'm mostly concerned about the readability of .td >

Dale, Sorry, I see you did say I should run the gcc tests. I apologize for forgetting this. I'll work on getting them to run here. Chris et. all, I have a fix for the assertion failure in the enclosed llvmmultalt8.patch file. I didn't realize the input constraints could have different numbers of alternatives from the outputs, which now makes sense. The pr20314-2.c file now compiles

Hi Quentin, > It sounds like you only need the earlyclobber description for the N, N > variant. > In other words, as long as you use different opcodes for widen-op NN and > widen-op WN, you model exactly what you want. > > What am I missing? > we are using different opcodes for widen-op NN and widen-op WN. My understanding is that not setting earlyclobber to the W, N

For any instruction, a list of constraints can be specified, like: let Constraints = "$dst = $lhs" in ... I checked the existing backends and I didn't notice any complex constraints: basically "Constraints" keyword is used to force 1 operand register to be the same as another one. I am wondering if there is any way to express more complicated constraints like for

Hello, I'm getting a machine verifier error after introducing the earlyclobber constraint to some instructions where the src and dest regs can't be the same. The offending instruction pattern is this one: let canFoldAsLoad = 1, isReMaterializable = 1, Constraints = "@earlyclobber $dst" in def LDDWRdPtrQ : Inst<(outs DREGS:$dst), (ins memri:$src),

Hi all, I'm working on a target whose registers have equal-sized subregisters and all of those subregisters can be named (or the other way round: registers can be grouped into super registers). So for instance we've got 16 registers W (as in wide) W0..W15 and 32 registers N (as in narrow) N0..N31. This way, W0 is made by grouping N0 and N1, W1 is N2 and N3, W2 is N4 and N5, ..., W15 is

Hi, I'd like to define a pseudo-instruction whose expansion will, as a side-effect, overwrite an input register's value: the pseudo-instruction ldw r1:r2, P to load 2 bytes from memory address P is to be expaneded to ld r1, P+ ld r2, P where "ld _, P+" is an instruction that loads a single byte from P, and post-increments P by one. How can I represent this behaviour in

On Jul 14, 2012, at 10:09 AM, Borja Ferrer <borja.ferav at gmail.com> wrote: > Hello, > > I'm getting a machine verifier error after introducing the earlyclobber constraint to some instructions where the src and dest regs can't be the same. The offending instruction pattern is this one: > > let canFoldAsLoad = 1, > isReMaterializable = 1, > Constraints =

Hi, How can I specify in a .td file that source and destination should not use the same register? Thanks. - Elena --------------------------------------------------------------------- Intel Israel (74) Limited This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. If

Hello Jakob, I'm still getting the error, I can give you any other debug info you need. I haven't pasted the regalloc debug info here because it is quite huge, but if you tell me what specific details you need I will include them. Thanks for your help! 2012/7/14 Jakob Stoklund Olesen <stoklund at 2pi.dk> > > On Jul 14, 2012, at 10:09 AM, Borja Ferrer <borja.ferav at

One other minor thing: I notice that in the inline assembly the result (rd) is constrained as an earlyclobber operand. What was the reason for that?

Is there a way to force the register allocator to avoid reusing an operand register for a definition? For example, the following machine instruction reuses a register for the first operand and definition: %uI7<def> = eq at III %uI7<kill>, %uI4 I'd like: %uI8<def> = eq at III %uI7<kill>, %uI4 I'm guessing that the right way to do this would be to kill the

On Wednesday 16 December 2009 12:54, Jim Grosbach wrote: > > That's better. Is there any way you could convince TableGen to > > recognize > > that 'constraints = "$success != $src", "$success != $ptr"' is > > semantically > > equivalent to earlyclobber? Maybe check that the common operand in > > both > > contraints is

On Jul 15, 2012, at 9:20 AM, Borja Ferrer <borja.ferav at gmail.com> wrote: > Jakob, one more hint, I've placed some asserts around the code you added and noticed that the InlineSpiller::insertReload() function is not being called. > > 2012/7/14 Borja Ferrer <borja.ferav at gmail.com> > Hello Jakob, > > I'm still getting the error, I can give you any other

On Sun, 28 May 2017, David Chisnall wrote: >> let Constraints = "@earlyclobber $reg" in >> def LDWRdPtr : Pseudo<(outs DREGS:$reg), >> (ins PTRREGS:$ptrreg), >> "ldw\t$reg, $ptrreg", >> [(set i16:$reg, (load i16:$ptrreg))]>, >>

On Sep 20, 2010, at 9:40 PMPDT, John Thompson wrote: > Thanks, Stuart. Sorry, I had some left-over editing cruft in my email. From Googling runtest, I had found dejagnu, which I'd heard some folks were using over there, so I used the local package manager to install it. But from what you said I went ahead and got the dejagnu sources and built it, but had problems in running make