[llvm] AMDGPU: Stop running assembler tests with default cpu (PR #117421)

[Ivan Kosarev via llvm-commits]

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@@ -1,4 +1,4 @@
-// RUN: llvm-mc -triple=amdgcn -show-encoding %s | FileCheck %s --check-prefixes=GCN,SICI
+// RUN: llvm-mc -triple=amdgcn -mcpu=tahiti -show-encoding %s | FileCheck %s --check-prefixes=GCN,SICI
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kosarev wrote:

Looks identical to the following RUN line.

https://github.com/llvm/llvm-project/pull/117421