[AArch64] Extra unit tests for trunc lowering of vectors

[nilanjana_basu]

Summary

These tests show code generation for vectorized trunc lowering from i16 to i8 in AArch64.
These tests should be updated when 'trunc' lowering of vectors is extended to use 'tbl' instructions.

[fhahn]

lgtm, thanks!

llvm/test/CodeGen/AArch64/trunc-to-tbl.ll

loop:
   store <11 x i8> %trunc, ptr %gep.dst
   %iv.next = add i64 %iv, 1
   %ec = icmp eq i64 %iv.next, 1000
   br i1 %ec, label %loop, label %exit
 
 exit:
   ret void
 }
+
+define void @trunc_v16i16_to_v16i8_in_loop(ptr %A, ptr %dst) {
+; CHECK-LABEL:  trunc_v16i16_to_v16i8_in_loop:
+; CHECK:    ; %bb.0:                                ; %entry
+; CHECK-NEXT:   mov x8, xzr
+; CHECK-NEXT:  LBB7_1:                                 ; %loop
+; CHECK-NEXT:                                          ; =>This Inner Loop Header: Depth=1
+; CHECK-NEXT:   add x9, x0, x8, lsl #5
+; CHECK-NEXT:   ldp q1, q0, [x9]
+; CHECK-NEXT:   uzp1.16b  v0, v1, v0
+; CHECK-NEXT:   str q0, [x1, x8, lsl  #4]
+; CHECK-NEXT:   add x8, x8, #1
+; CHECK-NEXT:   cmp x8, #1000
+; CHECK-NEXT:   b.eq  LBB7_1
+; CHECK-NEXT:  ; %bb.2:                                ; %exit
+; CHECK-NEXT:   ret
+
+; CHECK-BE-LABEL:  trunc_v16i16_to_v16i8_in_loop:
+; CHECK-BE:  // %bb.0:                               // %entry
+; CHECK-BE-NEXT:      mov x8, xzr
+; CHECK-BE-NEXT:  .LBB7_1:                                // %loop
+; CHECK-BE-NEXT:                                          // =>This Inner Loop Header: Depth=1
+; CHECK-BE-NEXT:    add x9, x0, x8, lsl #5
+; CHECK-BE-NEXT:    add x10, x9, #16
+; CHECK-BE-NEXT:    ld1 { v0.8h }, [x9]
+; CHECK-BE-NEXT:    add x9, x1, x8, lsl #4
+; CHECK-BE-NEXT:    add x8, x8, #1
+; CHECK-BE-NEXT:    ld1 { v1.8h }, [x10]
+; CHECK-BE-NEXT:    cmp x8, #1000
+; CHECK-BE-NEXT:    uzp1  v0.16b, v0.16b, v1.16b
+; CHECK-BE-NEXT:    st1 { v0.16b }, [x9]
+; CHECK-BE-NEXT:    b.eq  .LBB7_1
+; CHECK-BE-NEXT:  // %bb.2:                               // %exit
+; CHECK-BE-NEXT:    ret
+
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep.A = getelementptr inbounds <16 x i16>, ptr %A, i64 %iv
+  %l.A = load <16 x i16>, ptr %gep.A
+  %trunc = trunc <16 x i16> %l.A to <16 x i8>
+  %gep.dst = getelementptr inbounds <16 x i8>, ptr %dst, i64 %iv
+  store <16 x i8> %trunc, ptr %gep.dst
+  %iv.next = add i64 %iv, 1
+  %ec = icmp eq i64 %iv.next, 1000
+  br i1 %ec, label %loop, label %exit
+
+exit:
+  ret void
+}
+
+define void @trunc_v8i16_to_v8i8_in_loop(ptr %A, ptr %dst) {
+; CHECK-LABEL:  trunc_v8i16_to_v8i8_in_loop:
+; CHECK:    ; %bb.0:                                ; %entry
+; CHECK-NEXT:   mov x8, xzr
+; CHECK-NEXT:  LBB8_1:                                 ; %loop
+; CHECK-NEXT:                                          ; =>This Inner Loop Header: Depth=1
+; CHECK-NEXT:   ldr q0, [x0, x8, lsl  #4]
+; CHECK-NEXT:   xtn.8b  v0, v0
+; CHECK-NEXT:   str d0, [x1, x8, lsl  #3]
+; CHECK-NEXT:   add x8, x8, #1
+; CHECK-NEXT:   cmp x8, #1000
+; CHECK-NEXT:   b.eq  LBB8_1
+; CHECK-NEXT:  ; %bb.2:                                ; %exit
+; CHECK-NEXT:   ret
+
+; CHECK-BE-LABEL:  trunc_v8i16_to_v8i8_in_loop:
+; CHECK-BE:  // %bb.0:                               // %entry
+; CHECK-BE-NEXT:    mov x8, xzr
+; CHECK-BE-NEXT:  .LBB8_1:                                // %loop
+; CHECK-BE-NEXT:                                          // =>This Inner Loop Header: Depth=1
+; CHECK-BE-NEXT:    add x9, x0, x8, lsl #4
+; CHECK-BE-NEXT:    ld1 { v0.8h }, [x9]
+; CHECK-BE-NEXT:    add x9, x1, x8, lsl #3
+; CHECK-BE-NEXT:    add x8, x8, #1
+; CHECK-BE-NEXT:    cmp x8, #1000
+; CHECK-BE-NEXT:    xtn v0.8b, v0.8h
+; CHECK-BE-NEXT:    st1 { v0.8b }, [x9]
+; CHECK-BE-NEXT:    b.eq  .LBB8_1
+; CHECK-BE-NEXT:  // %bb.2:                               // %exit
+; CHECK-BE-NEXT:    ret
+
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %gep.A = getelementptr inbounds <8 x i16>, ptr %A, i64 %iv
+  %l.A = load <8 x i16>, ptr %gep.A
+  %trunc = trunc <8 x i16> %l.A to <8 x i8>
+  %gep.dst = getelementptr inbounds <8 x i8>, ptr %dst, i64 %iv
+  store <8 x i8> %trunc, ptr %gep.dst
+  %iv.next = add i64 %iv, 1
+  %ec = icmp eq i64 %iv.next, 1000
+  br i1 %ec, label %loop, label %exit
+
+exit:
+  ret void
+}