[RISCV][NFC] Test showing wrong scheduling of expansion of memmove for fixed RVV

[rogfer01]

Summary

After a memmove is expanded, we load the higher addresses after we have stored onto the lower ones, as if we could do a forward copy.

[rogfer01]

I'll post a fix shortly.

[craig.topper]

LGTM

llvm/test/CodeGen/RISCV/rvv/wrong-chain-fixed-load.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv64 -mattr=+v -riscv-v-vector-bits-min=128 < %s \
+; RUN:   | FileCheck %s
+
+@c = global [7 x i64] [i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7], align 8
+
+define void @do.memmove() nounwind {
+; CHECK-LABEL: do.memmove:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lui a0, %hi(c)
+; CHECK-NEXT:    addi a0, a0, %lo(c)
+; CHECK-NEXT:    vsetivli zero, 2, e64, m1, ta, mu
+; CHECK-NEXT:    vle64.v v8, (a0)
+; CHECK-NEXT:    addi a1, a0, 8
+; CHECK-NEXT:    vse64.v v8, (a1)
+; CHECK-NEXT:    addi a1, a0, 16
+; CHECK-NEXT:    vle64.v v8, (a1)
+; CHECK-NEXT:    addi a0, a0, 24
+; CHECK-NEXT:    vse64.v v8, (a0)
+; CHECK-NEXT:    ret
+entry:
+  ; this thing is "__builtin_memmove(&c[1], &c[0], sizeof(c[0]) * 4);"
+  tail call void @llvm.memmove.p0.p0.i64(
+        ptr noundef nonnull align 8 dereferenceable(32) getelementptr inbounds ([7 x i64], ptr @c, i64 0, i64 1),
+        ptr noundef nonnull align 8 dereferenceable(32) @c, i64 32, i1 false)
+  ret void
+}
+
+; Function Attrs: argmemonly mustprogress nofree nounwind willreturn
+declare void @llvm.memmove.p0.p0.i64(ptr nocapture writeonly, ptr nocapture readonly, i64, i1 immarg) #1
+
+attributes #1 = { argmemonly mustprogress nofree nounwind willreturn }