[llvm] [DAG] computeKnownFPClass - add ISD::EXTRACT_SUBVECTOR/INSERT_SUBVECTOR handling. (PR #190378)

[Matt Arsenault via llvm-commits]

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@@ -22,33 +22,105 @@ define i8 @iszero_constant_v4f32() nounwind {
   ret i8 %r
 }
 
-define <vscale x 4 x i1> @splat_constant_is_pos_normal() {
-; CHECK-LABEL: splat_constant_is_pos_normal:
+define i1 @extract_subvec(<8 x float> %a0){
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arsenm wrote:

Can you precommit these tests to show there's a difference 

https://github.com/llvm/llvm-project/pull/190378