similar to: [LLVMdev] [X86] DAG Combine - VSELECT

On Mon, Aug 19, 2013 at 3:34 PM, Juergen Ributzka <juergen at apple.com> wrote: > Hi @ll, > > I am wondering about the use of !isBeforeLegalize in PerformSELECTCombine > in the X86 backend. This defers all VSELECT related DAG combines until > after the Legalizer has run. If the IR has already only legal types the > second round of DAG combines is skipped and no VSELECT

I see. We still can use that shortcut to catch the simple case after type legalization, but we could also do a more elaborate type check before type legalization to enable it? On Aug 19, 2013, at 4:13 PM, Eli Friedman <eli.friedman at gmail.com> wrote: > On Mon, Aug 19, 2013 at 3:34 PM, Juergen Ributzka <juergen at apple.com> wrote: > Hi @ll, > > I am wondering about the

On Mon, Aug 19, 2013 at 4:17 PM, Juergen Ributzka <juergen at apple.com> wrote: > I see. We still can use that shortcut to catch the simple case after type > legalization, but we could also do a more elaborate type check before type > legalization to enable it? > If you're going to write the code to check the types anyway, it's probably clearer to remove the

Can this optimization be moved to the lowering phase? LowerVSELECT() ? - Elena From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Eli Friedman Sent: Tuesday, August 20, 2013 03:56 To: Juergen Ributzka Cc: Benjamin Kramer; LLVM Developers Mailing List Subject: Re: [LLVMdev] [X86] DAG Combine - VSELECT On Mon, Aug 19, 2013 at 4:17 PM, Juergen

If you mark VSELECT as 'expand' then it will be expanded to a sequence of AND/OR/XOR, which is pretty efficient (found in LegalizeVectorOps.cpp ExpandVSELECT). On Oct 11, 2012, at 11:05 AM, Jim Grosbach <grosbach at apple.com> wrote: > Seems reasonable to me. Plain 'SELECT' is already marked expand for vector types. I bet that just didn't get updates when VSELECT

Seems reasonable to me. Plain 'SELECT' is already marked expand for vector types. I bet that just didn't get updates when VSELECT was introduced. -Jim On Oct 11, 2012, at 10:25 AM, Peter Couperus <peter.couperus at st.com> wrote: > Hello, > > We've run into a couple of cases where we'd like to use select on vector types, but vselect handling is absent from

Hello, We've run into a couple of cases where we'd like to use select on vector types, but vselect handling is absent from the ARM backend. Would there be any potential harm by marking VSELECT as Expand on ARM targets with NEON? Adding this seems to fix the following PR's: http://llvm.org/bugs/show_bug.cgi?id=13831 http://llvm.org/bugs/show_bug.cgi?id=13961 Thanks! Pete

Hi all, I met the error while compiling the code with vector type with some architecture. IR is as following. %cmp = icmp sgt <3 x i8> %x, zeroinitializer %sub = sub <3 x i8> zeroinitializer, %x %cond = select <3 x i1> %cmp, <3 x i8> %x, <3 x i8> %sub 'select' IR is converted to 'vselect' dag and is combined to 'sra (X, size(X)-1); xor

Hi JinGu Kang, On 28/05/13 17:18, jingu kang wrote: > Hi all, > > I met the error while compiling the code with vector type with some > architecture. IR is as following. > > %cmp = icmp sgt <3 x i8> %x, zeroinitializer > %sub = sub <3 x i8> zeroinitializer, %x > %cond = select <3 x i1> %cmp, <3 x i8> %x, <3 x i8> %sub > >

Hello, I am getting this error. What instruction is required to be implemented? LLVM ERROR: Cannot select: t22: v32i32 = vselect t724, t11, t16 t724: v32i32,ch = load<LD128[FixedStack1]> t723, FrameIndex:i64<1>, undef:i64 t659: i64 = FrameIndex<1> t10: i64 = undef t11: v32i32,ch = load<LD128[%sunkaddr45](align=4)(tbaa=<0x481f1e8>)> t0, t8, undef:i64

On Mar 8, 2013, at 2:29 PM, Nadav Rotem <nrotem at apple.com<mailto:nrotem at apple.com>> wrote: Hi Richard, visitSIGN_EXTEND() in DAGCombiner.cpp generates an ISD::SELECT even if VT is a vector, which causes ExpandSELECT() to assert during legalization. I think what's required is to have visitSIGN_EXTEND generate a VSELECT if VT is a vector… ISD::SELECT should be used for

On Mar 11, 2013, at 9:41 AM, Nadav Rotem <nrotem at apple.com<mailto:nrotem at apple.com>> wrote: Hi Richard, I did… It originates from an icmp ne <2x i8>, zero initializer followed by a sext of the result 2x i1 to 2x i8. When we visit the SIGN_EXTEND, we generate the ISD::SELECT even though the selector and both operands are vectors. It sounds like a bug in the dag combine

Hi Richard, > visitSIGN_EXTEND() in DAGCombiner.cpp generates an ISD::SELECT even if VT is a vector, which causes ExpandSELECT() to assert during legalization. > I think what's required is to have visitSIGN_EXTEND generate a VSELECT if VT is a vector… ISD::SELECT should be used for cases where the selector is a scalar, even if the operands are vector. If you found a case where SELECT

Hi Richard, > > I did… It originates from an icmp ne <2x i8>, zero initializer followed by a sext of the result 2x i1 to 2x i8. When we visit the SIGN_EXTEND, we generate the ISD::SELECT even though the selector and both operands are vectors. > It sounds like a bug in the dag combine optimization. If you send me the line number I will take a look. >> We should probably

visitSIGN_EXTEND() in DAGCombiner.cpp generates an ISD::SELECT even if VT is a vector, which causes ExpandSELECT() to assert during legalization. I think what's required is to have visitSIGN_EXTEND generate a VSELECT if VT is a vector… I've tried a local change that cures this particular assert, but uncovers another assert later, so I'm a bit uncertain if I'm heading off in the

Hello. Because I experience optimizations (DCE, OoO schedule) which mess the correct semantics of the list of instructions lowered in ISelLowering from the VSELECT LLVM instruction, and these bad transformations happen even before scheduling, at later I-sel subpasses, I try to fix this problem by lowering VSELECT to only one pseudo-instruction and LATER translate it to a list of

> > Line 4501 in trunk DAGCombiner.cpp… I changed the ISD::SELECT to the VT.isVector() ? ISD::VSELECT : ISD::SELECT... > Thanks. From the commit message I think that we should only run this optimization on scalars. >> Can you write down the input SDNode ? What types are inputs ? > > 0x107046d10: v2i8 = vselect 0x107046c10, 0x107046b10, 0x107045e10 [ID=-3]

On Wed, Jul 27, 2011 at 3:50 PM, Matt Johnson <johnso87 at crhc.illinois.edu> wrote: > Hi Eli, > > On 07/27/2011 04:59 PM, Eli Friedman wrote: >> >> On Wed, Jul 27, 2011 at 2:28 PM, Matt Johnson >> <johnso87 at crhc.illinois.edu>  wrote: >>> >>> Hi All, >>>     I'm writing a backend for a target which only supports 4-byte,

Hi Rotem, What do you mean by "you can use the <4 x float> type for which the vselect works". Do you mean that then back-end can correctly split the operands when it is a four elements vector? I've try that, but it still fails. On Wed, Oct 19, 2011 at 4:21 PM, Rotem, Nadav <nadav.rotem at intel.com> wrote: > This is indeed a bug. I get a different error on my

Jeff Bush <jeffbush001 at gmail.com> writes: > Ah, I think I get it now. This was mentioned earlier in the thread, > but it didn't click at the time. It sounds like I can do instruction > selection with a pattern like (omitting selection of the sources): > > let Constraints = "$dst = $oldvalue" in { > def MASKEDARITH : MyInstruction< >