similar to: Code which should exit 1 is exiting 0

My understanding is that this checks whether the bit width of the integer *type* fits in the bit width of the mantissa, not the bit width of the integer value. - CL > On Apr 14, 2016, at 6:02 PM, escha at apple.com wrote: > > We already do this to some extent; see this code in InstCombineCasts: > > // fpto{s/u}i({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X) > //

I am not entirely sure this is safe. Transforming this to an fsub could change the value stored on platforms that implement negates using arithmetic instead of with bitmath (such as ours) and either canonicalize NaNs or don’t support denormals. This is actually important because this kind of bitmath on floats is very commonly used as part of algorithms for complex math functions that need to get

Sure On Mon, Jul 4, 2016, 9:40 AM Carlos Liam <carlos at aarzee.me> wrote: > It looks like there's already something similar in PropagateEquality which > eg X >= Y == true and replaces X < Y == false, which is somewhat similar - > could I base an addition off of that? > > > - CL > > On Jul 3, 2016, at 7:13 PM, Daniel Berlin <dberlin at dberlin.org>

It's going to be really hard to do something sane in the current infrastructure. Its possible, but it would also be slow. You would have to go looking at uses of variables compared in predicates in PropagateEquality and if the uses appear in a comparison that is dominated by the true or false edge of the existing predicate, see if it tells you something about the dominated one. On Mon, Jul

Looks like LVI actually does have cases for max and min; would it be better to allow ValueTracking to use range analysis instead? - CL > On Aug 1, 2016, at 8:44 PM, Philip Reames <listmail at philipreames.com> wrote: > >> On 07/29/2016 07:08 PM, Carlos Liam via llvm-dev wrote: >> Hi all, >> >> Say we have this IR: >> >> %1 = icmp slt i16 %x, 0

PropagateEquality in gvn.cpp However, if you are going to do it, remember the goal is to make the code simpler and easier, not just pile on to the current mess to catch more cases :) On Mon, Jul 4, 2016, 7:51 AM Carlos Liam <carlos at aarzee.me> wrote: > Where would I look to change the equality propagation? > > > - CL > > On Jun 30, 2016, at 11:45 PM, Daniel Berlin

Good point. The same argument seems to apply to copy() too so I suppose it depends how strict we want to be about it. From: fglaser at apple.com [mailto:fglaser at apple.com] On Behalf Of escha at apple.com Sent: 11 April 2016 20:55 To: Daniel Sanders Cc: Alex Rosenberg; llvm-dev at lists.llvm.org; Carlos Liam Subject: Re: [llvm-dev] Implementing a proposed InstCombine optimization On Apr 11,

It’s definitely one that would need some target hooks, and is probably not actually worth doing without analysing the producers and consumers of the value. If the source and destination values need to be in floating point registers, the cost of FPR<->GPR moves is likely to be a lot higher than the cost of the subtract, even if the xor is free. If the results are going to end up in integer

I'm saying at the IR level, not the C level. IR makes certain assumptions about the representation of floating point numbers. Nothing to do with C, I only used it as an example. - CL > On Apr 14, 2016, at 4:49 PM, Martin J. O'Riordan <martin.oriordan at movidius.com> wrote: > > I don't think that this is correct. > > | Let's say we have an int x, and we

> I am not entirely sure this is safe. Transforming this to an fsub could change the value stored on platforms that implement negates using arithmetic instead of with bitmath (such as ours) I think it's probably safe for IEEE754-2008 conformant platforms because negation was clarified to be a non-arithmetic bit flip that cannot cause exceptions in that specification. However, I'm sure

Hi, I'm interested in implementing an InstCombine optimization that I discovered and verified with Alive-NJ (with the help of the authors of Alive-NJ). The optimization is described in Alive-NJ format as follows: Name: xor->fsub Pre: isSignBit(C) %x = bitcast %A %y = xor %x, C %z = bitcast %y => %z = fsub -0.0, %A Effectively the optimization targets code that casts a float to an int

Hello, Recently I have stumbled across an almost double performance decrease in one of my codebases when compiling with clang instead of gcc. I was testing with the currently latest 3.9.1 as well as 4.0.0 rc2 targeting x86-64 darwin with -Ofast, and after some investigation was able to narrow down the code to the following snippet: __attribute__ ((noinline)) bool calculate(double c) { uint32_t

Is there anywhere in the codebase that actually uses the ConvertAction to determine how conversion functions are lowered? In SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) ... case ISD::SINT_TO_FP: case ISD::UINT_TO_FP: case ISD::EXTRACT_VECTOR_ELT: Action = TLI.getOperationAction(Node->getOpcode(), Node->getOperand(0).getValueType());

The current gvn equality propagation is not powerful enough to get this because it doesn't try to infer values in predicates based on other predicates, so it never realizes a>b -> a !=b in a useful way. It otherwise would get this On Thu, Jun 30, 2016, 7:41 PM Sean Silva <chisophugis at gmail.com> wrote: > On Thu, Jun 30, 2016 at 6:45 PM, Daniel Berlin via llvm-dev <

On Mar 19, 2010, at 12:23 PM, Villmow, Micah wrote: > Is there anywhere in the codebase that actually uses the ConvertAction to determine how conversion functions are lowered? I don't see any. > > In SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) > > ... > case ISD::SINT_TO_FP: > case ISD::UINT_TO_FP: > case ISD::EXTRACT_VECTOR_ELT: > Action =

> On Mar 11, 2016, at 5:28 PM, Sean Silva <chisophugis at gmail.com> wrote: > > > > On Fri, Mar 11, 2016 at 12:47 PM, Vedant Kumar <vsk at apple.com> wrote: > There have been a lot of responses. I'll try to summarize the thread and respond > to some of the questions/feedback. > > > Summary > ======= > > 1. We should teach GlobalDCE to

On Fri, Mar 11, 2016 at 7:04 PM, Sean Silva <chisophugis at gmail.com> wrote: > > > On Fri, Mar 11, 2016 at 6:00 PM, Vedant Kumar <vsk at apple.com> wrote: > >> >> > On Mar 11, 2016, at 5:28 PM, Sean Silva <chisophugis at gmail.com> wrote: >> > >> > >> > >> > On Fri, Mar 11, 2016 at 12:47 PM, Vedant Kumar <vsk at

> > Instead of adding the operands to a list, erase the instruction and add them to the worklist wouldn’t be probably faster something like: > > if (Instruction *Used = dyn_cast<Instruction>(*OI)) > if (Used->hasOneUse()) > WorkList.insert(Used); > > If it has one use is going to be the instruction we are going to remove anyway, right? I don’t think this

Hi Escha, We certainly would love to generalize them as long as the performance doesn't suffer in general. If you have specific use cases that are regressed due to these optimizations, I am more than happy to take a look. On Mon, Aug 24, 2015 at 6:43 PM, escha <escha at apple.com> wrote: > > On Aug 24, 2015, at 11:10 AM, Jingyue Wu via llvm-dev < > llvm-dev at

2015-07-08 17:58 GMT+02:00 escha <escha at apple.com>: > [...] > > If you want to “revert" this sort of thing, you can do it at Select() time > or PreprocessISelDAG(), which is what I did on an out-of-tree backend to > turn add X, -C into sub X, C on selection time. This still lets all the > intermediate optimizations take advantage of the canonicalization. > >