similar to: [LLVMdev] (tablegen) Machine instruction without result

On Dec 5, 2008, at 6:53 AMPST, Christian Sayer wrote: > Hello, > > I am working on the backend for an architecture which has a compare > instruction that affects only an internal condition code register > (basically a sub without destination register). You want to model the condition codes as a pseudo-register rather than using OutFlag. See the X86 back end. > I get the

While looking at what llvm writes for this testcase, I noticed that there is one redundant operation in resulting assembly. The second 'cmp' operation there is essentially identical to the first one, with reversed order of arguments. Therefore, it is not needed. This testcase is a simple integer comparison routine, similar to what qsort would take to sort an integer array. I think

> > Basically, flag operands are a hack used to handle resources that > are not > > accurately modeled in the scheduler (e.g. condition codes, explicit > > register assignments, etc). The basic idea of the flag operand is > that > > they require the scheduler to keep the "flagged" nodes stuck > together in > > the output machine instructions. >

> Basically, flag operands are a hack used to handle resources that are not > accurately modeled in the scheduler (e.g. condition codes, explicit > register assignments, etc). The basic idea of the flag operand is that > they require the scheduler to keep the "flagged" nodes stuck together in > the output machine instructions. >From an user point of view, flags have

On Mon, 9 Oct 2006, Roman Levenstein wrote: > But your previous explanations were so good that I implemented in my > backend last week almost the same that you've done now in the > X86InstrSSE.td. I even introduced isCommutable parameter to indicate > this property, just as you did. So, by now integer arithmetic and > general purpose instructions are implemented. I'm working

On Jun 13, 2012, at 1:15 PM, Sergei Larin <slarin at codeaurora.org> wrote: > Andy, > > You are probably right here – look at this – before phi elimination this code looks much more sane: > > # *** IR Dump After Live Variable Analysis ***: > # Machine code for function push: SSA > Function Live Outs: %R0 > > BB#0: derived from LLVM BB %entry >

Hi All, The following code : void hexagon2( int *a, int *res ) { int i = 100; while ( i-- ) { *res++ = *a++; } } gets compiled as a sub-optimal Software loop on LLVM 9.0 instead of a Hardware loop, whereas it was compiled as a Hardware Loop in LLVM 7.0. This is the final assembly code generated by LLVM 9.0 : .text .file "main.c" .globl hexagon2 // --

On Jun 13, 2012, at 10:49 AM, Sergei Larin <slarin at codeaurora.org> wrote: > So if this early exit is taken: > > // SSA defs do not have output/anti dependencies. > // The current operand is a def, so we have at least one. > if (llvm::next(MRI.def_begin(Reg)) == MRI.def_end()) > return; > > we do not ever get to this point: > >

Ok, after a long detour I am back to where I have started. I think there is a problem at dep DAG construction. Let me try to convince you. Here is the C code we are dealing with: push () { struct xx_stack *stack, *top; for (stack = xx_stack; stack; stack = stack->next) top = stack; yy_instr = top->first; } If the loop never iterates, "top" will have

On Sep 18, 2012, at 1:45 PM, Bjorn De Sutter <bjorn.desutter at elis.ugent.be> wrote: > I am working on a backend for a CGRA architecture with advanced predicate support (as on EPIC machines and as first used in the OpenIMPACT compiler). Until last month, the backend was working fine, but since the r161643 commit by stoklund, my backend doesn't work anymore. I think I noticed some

Sergei, Absolutely right, the copy/ldriw should not be reordered. I was attempting to explain that I consider it a phi-elimination bug, not a DAG builder bug. Liveness will also have problems with this code in the long run. To avoid confusion, I filed PR13112: Phi elimination generates uninitialized vreg uses, and disabled the SSA check until its fixes in r158461. However, your C code is also

Andy, You are probably right here - look at this - before phi elimination this code looks much more sane: # *** IR Dump After Live Variable Analysis ***: # Machine code for function push: SSA Function Live Outs: %R0 BB#0: derived from LLVM BB %entry %vreg5<def> = IMPLICIT_DEF; IntRegs:%vreg5 %vreg4<def> = TFRI_V4 <ga:@xx_stack>; IntRegs:%vreg4

Hi, I am working on a backend for a CGRA architecture with advanced predicate support (as on EPIC machines and as first used in the OpenIMPACT compiler). Until last month, the backend was working fine, but since the r161643 commit by stoklund, my backend doesn't work anymore. I think I noticed some related commits later on, and the assertion I get on the latest trunk (r164162) differs from

Hi, I was wondering if there is a way to specify macros to help shorten rewriting patterns like these: def : Pat <(v4i8 (mul (v4i8 IntRegs:$a), (v4i8 IntRegs:$b))), (v4i8 (VTRUNEHB (v4i16 (VTRUNEWH (v2i32 (VMPYH (v2i16 (EXTRACT_SUBREG (v4i16 (VSXTBH (v4i8 IntRegs:$a))), subreg_hireg)), (v2i16 (EXTRACT_SUBREG (v4i16 (VSXTBH (v4i8

I want to generate the instruction like addi 40, r3 ! i.e. r3 = r3 + 40 The format i wrote is def ADDI : F1<opcode, (outs IntRegs:$dst), (ins IntRegs:$dst, i32imm:$imm) "addi $imm, $dst", [(set $IntRegs:$dst, (add $IntRegs:$dst, i32imm:$c))] but it is not compiling. what should be the format. vikram -- View this message

Andy, Lang, Thanks for the suggestion. I have spent more time with it today, and I do see some strange things in liveness update. I am not at the actual cause yet, but here is what I got so far: I have the following live ranges when I start scheduling a region: R2 = [0B,48r:0)[352r,416r:5)... R3 = [0B,48r:0)[368r,416r:5)... R4 = [0B,32r:0)[384r,416r:4)... R5 = [0B,32r:0)[400r,416r:4)...

Hi! I'm writing a new back-end for a new architecture. First, I'll do some "tests" with an existing back-end (I chose the Sparc back-end). My architecture has special address-registers and I want to add such new address-registers to my Sparc back-end. 1) I defined a new register call AddrRegs 2) I registered the class AddrRegs (addRegisterClass(MVT::iPTR, .. )) 3) I

Hello everyone, I am working on a release based on the branch 3.1 version of code. Unfortunately it has enough differences that exact rev does not apply. I am hitting an assert in liveness update with seemingly trivial code (attached). /local/mnt/workspace/slarin/tools/llvm-mainline-merged/lib/CodeGen/LiveInter valAnalysis.cpp:1078: void

On Aug 30, 2012, at 1:20 PM, Arnold Schwaighofer <arnolds at codeaurora.org> wrote: > The code in collectRanges() does: > > // Collect ranges for register units. These live ranges are computed on > // demand, so just skip any that haven't been computed yet. > if (TargetRegisterInfo::isPhysicalRegister(Reg)) { > for (MCRegUnitIterator Units(Reg,

Hi Sergei, Andy, Sorry - I got distracted with some other work. I'm looking into this and PR13719 now. I'll let you know what I find out. Sergei - thanks very much for the investigation. That should help me pin this down. Cheers, Lang. On Tue, Aug 28, 2012 at 2:33 PM, Sergei Larin <slarin at codeaurora.org> wrote: > Andy, Lang, > > Thanks for the suggestion. >