[llvm] [AArch64] Use GISel for optnone functions (PR #174746)

[Matt Arsenault via llvm-commits]

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@@ -160,6 +160,10 @@ static cl::opt<int> EnableGlobalISelAtO(
     cl::desc("Enable GlobalISel at or below an opt level (-1 to disable)"),
     cl::init(0));
 
+static cl::opt<bool> EnableGlobalISelForOptNone(
+    "aarch64-enable-global-isel-for-optnone", cl::Hidden,
+    cl::desc("Route optnone functions through GlobalISel"), cl::init(true));
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arsenm wrote:

I don't want yet another knob for this, much less a target specific one. Just use the existing control for which selector to use 

https://github.com/llvm/llvm-project/pull/174746