[llvm] [LV] Check for vector-to-scalar casts in legalizer (PR #106244)

[Ramkumar Ramachandra via llvm-commits]

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@@ -0,0 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt --force-widen-divrem-via-safe-divisor=false -passes=loop-vectorize -S --debug-only=loop-vectorize < %s 2>&1 | FileCheck %s
+
+define void @vector_to_scalar_cast(ptr %out) {
+; CHECK-LABEL: define void @vector_to_scalar_cast(
+; CHECK-SAME: ptr [[OUT:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[VEC0:%.*]] = insertelement <2 x i16> undef, i16 0, i64 0
+; CHECK-NEXT:    [[VEC1:%.*]] = insertelement <2 x i16> [[VEC0]], i16 0, i64 1
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[ADD:%.*]], %[[LOOP]] ], [ 1, %[[ENTRY]] ]
+; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp ne i32 [[IV]], 11
+; CHECK-NEXT:    [[ADD]] = add nuw nsw i32 [[IV]], 1
+; CHECK-NEXT:    [[VEC_SCALAR_CAST:%.*]] = bitcast <2 x i16> [[VEC1]] to i32
+; CHECK-NEXT:    [[SREM:%.*]] = srem i32 0, [[VEC_SCALAR_CAST]]
+; CHECK-NEXT:    store i32 [[SREM]], ptr [[OUT]], align 4
+; CHECK-NEXT:    br i1 [[EXITCOND]], label %[[LOOP]], label %[[EXIT:.*]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %vec0 = insertelement <2 x i16> undef, i16 0, i64 0
+  %vec1 = insertelement <2 x i16> %vec0, i16 0, i64 1
+  br label %loop
+
+loop:
+  %iv = phi i32 [ %add, %loop ], [ 1, %entry ]
+  %exitcond = icmp ne i32 %iv, 11
+  %add = add nuw nsw i32 %iv, 1
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artagnon wrote:

Nit: s/%add/%iv.next/.

https://github.com/llvm/llvm-project/pull/106244