Displaying 2 results from an estimated 2 matches for "reducebuildvectoshuffle".
2018 Apr 09
2
A way to opt out of a dag combine?
...be erased by git merge
and generally doesn't look ideal. Writing the inverse transform in target
specific code doesn't work in this instance and in general creates an
infinite loop.
Guidance would be very welcome!
Thanks
For the curious, the specific instance I would like to avoid is
reduceBuildVecToShuffle.
It doesn't seem to have any target specific hooks. Exhaustive testing of
x86-64 vector code doesn't show the error. I think the other in tree
targets would notice the vector transform getting the answer wrong (it's
harder to confirm without hardware), so the bug is probably inert for i...
2018 Apr 09
1
llvm-dev Digest, Vol 166, Issue 22
...his.
Thank you
>From your description it seems like you are seeing an incorrect
behavior. If that's the case, it should definitely be fixed. Could you
provide the complete DAG before and after the erroneous transformation?
-Krzysztof
Combining: t25: v2i16 = BUILD_VECTOR t27, t22
Before reduceBuildVecToShuffle
SelectionDAG has 14 nodes:
t0: ch = EntryToken
t2: v4i16,ch = CopyFromReg t0, Register:v4i16 %0 // [a b c d]
t26: v2i16 = extract_subvector t2, Constant:i32<0> // [a b]
t27: i16 = extract_vector_elt t26, Constant:i32<0> // [a]
t21: v2i16 = extract_subvect...