[llvm] [AArch64] Model ZA array using inaccessible memory (PR #132058)

[Kerry McLaughlin via llvm-commits]

================
@@ -507,3 +522,35 @@ declare <vscale x 4 x i32> @llvm.aarch64.sme.readq.vert.nxv4i32(<vscale x 4 x i3
 declare <vscale x 4 x float> @llvm.aarch64.sme.readq.vert.nxv4f32(<vscale x 4 x float>, <vscale x 4 x i1>, i32, i32)
 declare <vscale x 2 x i64> @llvm.aarch64.sme.readq.vert.nxv2i64(<vscale x 2 x i64>, <vscale x 2 x i1>, i32, i32)
 declare <vscale x 2 x double> @llvm.aarch64.sme.readq.vert.nxv2f64(<vscale x 2 x double>, <vscale x 2 x i1>, i32, i32)
+
+; ------------------------------------------------------------------------------
+; Dummy external functions to force code retention.
+; The compiler does not see their implementations, so it must keep the calls.
+; ------------------------------------------------------------------------------
+
+declare void @dummy_use_8_nxv16i8(
+  <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>,
+  <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>, <vscale x 16 x i8>
+)
+
+declare void @dummy_use_4_nxv8i16(
+  <vscale x 8 x i16>, <vscale x 8 x i16>, <vscale x 8 x i16>, <vscale x 8 x i16>
+)
+
+declare void @dummy_use_8_nxv8f16(
+  <vscale x 8 x half>, <vscale x 8 x half>, <vscale x 8 x half>, <vscale x 8 x half>,
+  <vscale x 8 x half>, <vscale x 8 x half>, <vscale x 8 x half>, <vscale x 8 x half>
+)
+
+declare void @dummy_use_8_nxv8bf16(
+  <vscale x 8 x bfloat>, <vscale x 8 x bfloat>, <vscale x 8 x bfloat>, <vscale x 8 x bfloat>,
+  <vscale x 8 x bfloat>, <vscale x 8 x bfloat>, <vscale x 8 x bfloat>, <vscale x 8 x bfloat>
+)
+
+declare void @dummy_use_2_nxv4i32(<vscale x 4 x i32>, <vscale x 4 x i32>)
+
+declare void @dummy_use_4_nxv4f32(
+  <vscale x 4 x float>, <vscale x 4 x float>, <vscale x 4 x float>, <vscale x 4 x float>
+)
+
+declare void @dummy_use_2_nxv2f64(<vscale x 2 x double>, <vscale x 2 x double>)
----------------
kmclaughlin-arm wrote:

Would it be possible to add a single function that takes a variable number of arguments instead? e.g.
```suggestion
declare void @use(...)
```

https://github.com/llvm/llvm-project/pull/132058