In D81791#2138692, @RKSimon wrote:

@yubing @pengfei @craig.topper Please can you confirm the regressions have now been addressed?

In D79987#2065821, @RKSimon wrote:

@yubing I think my fixes for PR45974 have addressed this now - please can you confirm?

In D80906#2065694, @craig.topper wrote:

Broadcast should only demand the lowest element. The recursive call to SimplifyDemandedVectorElts call is supposed to ignore the incoming DemandedElts if the SDValue has more than one use.

In D79987#2041642, @RKSimon wrote:

I'm still looking at fixing getFauxShuffleMask (PR45974) but that might take a while, so this sort of approach is probably necessary.

Did you investigate replacing getTargetShuffleInputs with getTargetShuffleAndZeroables in the SimplifyDemandedBitsForTargetNode/SimplifyDemandedVectorEltsForTargetNode?

PING @RKSimon

In D79987#2038738, @RKSimon wrote:

Really we need to stop creating nodes inside getFauxShuffle - I'm going to see if we can do this without too many regressions.

@RKSimon , you're right. After checking https://reviews.llvm.org/rL146415, I found the makefile has disable this testcase for i386.

Committed in https://github.com/llvm/llvm-test-suite/commit/16265f5a73211d7497e41af43e895eb230c13b89

In D67210#1659230, @RKSimon wrote:

Please abandon this, it isn't a valid solution to the issue (raised at PR43227). I have a WIP fix that will address this correctly.

I've submit a patch to solve the bug which I commented yesterday.
https://reviews.llvm.org/D67210

Hi, Simon. This patch has produced a bug in llvm: