[llvm] [AMDGPU] Tolerate AMDGPUTargetELFStreamer without initializeTargetID (PR #226495)

[Tim Renouf via llvm-commits]

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@@ -209,6 +209,18 @@ class AMDGPUTargetELFStreamer final : public AMDGPUTargetStreamer {
   unsigned getEFlagsV4();
   unsigned getEFlagsV6();
 
+  // Override of AMDGPUTargetStreamer::getTargetID that tolerates
+  // initializeTargetID not having been called by initializing it here from our
+  // MCSubtargetInfo. This allows the use of AMDGPUTargetELFStreamer in an
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trenouf wrote:

In particular, without the fix, the test asserts in AMDGPUTargetELFStreamer::getEFlagsV3() because getTargetID() returns an empty optional, which it then tries to call isXnackOnOrAny() etc on.

https://github.com/llvm/llvm-project/pull/226495