search for: istruncatefree

Hi, I noticed many functions in the TargetTransformInfo interface are duplicates of those already in TargetLowering (e.g. isTruncateFree). Is the expectation really that targets will reimplement the same functions twice? AArch64’s TTI uses some TLI calls in some of its implementations, but why doesn’t the base TargetTransformInfo call the TargetLowering versions by default? - Matt

Hi Renato, I think that we need to improve ::isTruncateFree, ::isZextFree, etc to include all of the free conversions. Vector and Scalar. Non-free conversions are marked with setOperationAction so the generic parts of TTI should be able to give a reasonable cost estimation. The cost tables should contain cases that are not handled by TTI. So, if we have...

Hi all, I'm looking for a place where to put the costs of vector (and scalar) cast operations for ARM, but I noticed the TargetTransform methods call the TargetLowering ones when unsure. Now, I'm not sure... Many casts on ARM are free, and I could build a list of cases where it is true, but should I put this on the lowering or the transform? My main motivation is to get the costs right

...itecture truncate is free, but zext is not (and i64 is not a desirable type for xor or any binary operation in general), so I would expect this optimization to be bypassed but because of the following statement : (N0.getOpcode() == ISD::TRUNCATE && (!TLI.isZExtFree(VT, Op0VT) || !TLI.isTruncateFree(Op0VT, VT)) it is not (as isZExtFree return false for my architecture while isTruncateFree returns true). The comment on binop simplification says that binop over truncs should be optimize only if trunc is not free, so I do not understand the point of adding !isZExtFree at this point. Can someon...

On 25 January 2013 17:48, Nadav Rotem <nrotem at apple.com> wrote: > I think that we need to improve ::isTruncateFree, ::isZextFree, etc to > include all of the free conversions. Vector and Scalar. > Hi Nadav, Yes, and the question is: TargetLowering's isZExtFree or TargetTransform's isZExtFree? TargetTransform (TT) only has the free checks on types, while TargetLowering (TL) has on SDValue and de...

...backend, using the CPU's capability that truncating i16 to i8 is simply accessing an i16' register's subreg? Should this be handled in "LowerOperation" or in "PerformDAGCombine"? Or could this be done with a target-independent combine? Would returning true in "isTruncateFree" suffice? Is any lowering code needed at all? The X86 backend seems to do both, "setTargetDAGCombine(ISD::TRUNCATE)", but then also registering a lot of MVTs via "setOperationAction(...,Custom)", depending on things like soft-float. I guess I'm And second: In my cas...