[llvm] [AArch64][SME] Add remarks to flag lazy ZA saves, and SMSTART/SMSTOP transitions (PR #68255)

[Sander de Smalen via llvm-commits]

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@@ -7362,6 +7363,18 @@ AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
   else if (auto *ES = dyn_cast<ExternalSymbolSDNode>(CLI.Callee))
     CalleeAttrs = SMEAttrs(ES->getSymbol());
 
+  auto DescribeCallsite =
+      [&](OptimizationRemarkAnalysis &R) -> OptimizationRemarkAnalysis & {
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sdesmalen-arm wrote:

nit: Would it be easier to have a function that takes just a StringRef, so that you can do `EmitSMERemarkForCall("requires a streaming mode transition");`? You can then hide the construction of the ORE and OptimizationRemarkAnalysis in this lambda.

https://github.com/llvm/llvm-project/pull/68255