[llvm] [SPIR-V] Diagnose stores into read-only storage classes (PR #207331)

[Juan Manuel Martinez Caamaño via llvm-commits]

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@@ -0,0 +1,21 @@
+; RUN: not llc -verify-machineinstrs -O0 -mtriple=spirv64-unknown-unknown %s -o /dev/null 2>&1 | FileCheck %s
+; RUN: not llc -verify-machineinstrs -O0 -mtriple=spirv32-unknown-unknown %s -o /dev/null 2>&1 | FileCheck %s
+
+; Storing into addrspace(2) (__constant / UniformConstant) is read-only in SPIR-V.
+; The backend must diagnose this rather than emit invalid SPIR-V.
+
+; CHECK: error: {{.*}}store into a read-only SPIR-V storage class is not allowed
+
+define spir_kernel void @fuzz_kernel(ptr addrspace(1) %in, ptr addrspace(2) %out, i32 %n) {
+entry:
+  %ok = icmp sgt i32 %n, 0
+  br i1 %ok, label %body, label %exit
+body:
+  %v = load i32, ptr addrspace(1) %in, align 4
+  %salt = mul i32 %n, -1640531527
+  %mix = xor i32 %v, %salt
+  store i32 %mix, ptr addrspace(2) %out, align 4
+  br label %exit
+exit:
+  ret void
+}
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jmmartinez wrote:

Is it possible to reduce the test-case?

It looks to me that a simple `store i32 0, ptr addrspace(2) %out` would trigger the error condition already.

https://github.com/llvm/llvm-project/pull/207331