search for: lhsmask

Hi all, I'm having some trouble understanding the following lines in InstructionCombining.cpp, which possibly contain a bug: if (Mask[i] >= 2*e) NewMask.push_back(2*e); else NewMask.push_back(LHSMask[Mask[i]]); When Mask[i] is bigger than the size of LHSMask it reads out of bounds on that last line. I believe the first line is there to try to prevent that but then it should be comparing to LHSMask.size() not 2*e (e being Mask.size()). And when Mask[i] is bigger than the mask size the shuffl...

Hi Stefanus, Thanks for the info. I still think it's a bug though. Take for example a case where the vectors each have four elements. The values in Mask[] can range from 0 to 7, while HLSMask only has 4 elements. So LHSMask[Mask[i]] can go out of bounds, no? Cheers, Nicolas From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Stefanus Du Toit Sent: woensdag 1 april 2009 16:31 To: LLVM Developers Mailing List Subject: Re: [LLVMdev] Shuffle combine Hi Nicolas, On...

...VMdev] Shuffle combine On 1-Apr-09, at 12:42 PM, Nicolas Capens wrote: Hi Stefanus, Thanks for the info. I still think it's a bug though. Take for example a case where the vectors each have four elements. The values in Mask[] can range from 0 to 7, while HLSMask only has 4 elements. So LHSMask[Mask[i]] can go out of bounds, no? Good point! One easy way to fix this would be to use: if (Mask[i] >= e) { instead. The code could also be improved to consider the new mask equal to lhsmask/mask in places where they both refer to undefined elements. Stefanus Cheers, Ni...

On 1-Apr-09, at 12:42 PM, Nicolas Capens wrote: > Hi Stefanus, > > Thanks for the info. I still think it’s a bug though. Take for > example a case where the vectors each have four elements. The values > in Mask[] can range from 0 to 7, while HLSMask only has 4 elements. > So LHSMask[Mask[i]] can go out of bounds, no? Good point! One easy way to fix this would be to use: if (Mask[i] >= e) { instead. The code could also be improved to consider the new mask equal to lhsmask/mask in places where they both refer to undefined elements. Stefanus > Cheers, > > Nic...

Hi Nicolas, On 1-Apr-09, at 7:34 AM, Nicolas Capens wrote: > I’m having some trouble understanding the following lines in > InstructionCombining.cpp, which possibly contain a bug: > > if (Mask[i] >= 2*e) > NewMask.push_back(2*e); > else > NewMask.push_back(LHSMask[Mask[i]]); > > When Mask[i] is bigger than the size of LHSMask it reads out of > bounds on that last line. I believe the first line is there to try > to prevent that but then it should be comparing to LHSMask.size() > not 2*e (e being Mask.size()). Upon quick inspection of the...

...On 1-Apr-09, at 12:42 PM, Nicolas Capens wrote: > Hi Stefanus, > > Thanks for the info. I still think it’s a bug though. Take for > example a case where the vectors each have four elements. The values > in Mask[] can range from 0 to 7, while HLSMask only has 4 elements. > So LHSMask[Mask[i]] can go out of bounds, no? > > Good point! One easy way to fix this would be to use: > > if (Mask[i] >= e) { > > instead. The code could also be improved to consider the new mask > equal to lhsmask/mask in places where they both refer to undefined > elements....

Hi! Is there a pass that optimizes vector operations? If I have for examle a sequence of shufflevector instructions that optimizes them? (in opencl notation e.g. a.xyzw.wzyx.xxxx -> a.wwww) -Jochen

Instcombine does of this, late codegen also does some of it. -Chris On May 14, 2010, at 5:58 AM, Jochen Wilhelmy <j.wilhelmy at arcor.de> wrote: > Hi! > > Is there a pass that optimizes vector operations? > If I have for examle a sequence of shufflevector instructions > that optimizes them? > (in opencl notation e.g. a.xyzw.wzyx.xxxx -> a.wwww) > > -Jochen

..., LHSShiftAmt); else - Rot = DAG.getNode(ISD::ROTR, VT, LHSShift.getOperand(0), - RHSShift.getOperand(1)); + Rot = DAG.getNode(ISD::ROTR, VT, LHSShiftArg, RHSShiftAmt); // If there is an AND of either shifted operand, apply it to the result. if (LHSMask.Val || RHSMask.Val) { @@ -1532,35 +1533,71 @@ // fold (or (shl x, y), (srl x, (sub 32, y))) -> (rotl x, y) // fold (or (shl x, y), (srl x, (sub 32, y))) -> (rotr x, (sub 32, y)) - if (RHSShift.getOperand(1).getOpcode() == ISD::SUB && - LHSShift.getOperand(1) == RHSShif...