[clang] [clang] Add sincos builtin using `llvm.sincos` intrinsic (PR #114086)

[Benjamin Maxwell via cfe-commits]

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@@ -3232,6 +3264,22 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
       return RValue::get(emitUnaryMaybeConstrainedFPBuiltin(
           *this, E, Intrinsic::sinh, Intrinsic::experimental_constrained_sinh));
 
+    case Builtin::BIsincos:
+    case Builtin::BIsincosf:
+    case Builtin::BIsincosl:
+    case Builtin::BI__builtin_sincos:
+    case Builtin::BI__builtin_sincosf:
+    case Builtin::BI__builtin_sincosl:
+      // Only use the llvm.sincos.* builtin on AArch64 with optimizations.
+      // Currently, getting codegen that is no worse than the direct call
+      // requires using AA during codegen. This is not done at optlevel=none,
+      // and not all targets support this (AArch64 is one of the few known to).
+      if (!getTarget().getTriple().isAArch64() ||
+          CGM.getCodeGenOpts().OptimizationLevel == 0)
+        break;
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MacDue wrote:

Given the lack of reply, I'm going to limit this initial patch to only lower to `llvm.sincos.*` for the `__builtin` variants (similar to `frexp`). I'll consider broadening this in later patches. 

https://github.com/llvm/llvm-project/pull/114086