[llvm] [IR] Add `llvm.sincos` intrinsic (PR #109825)

[Sander de Smalen via llvm-commits]

================
@@ -15870,6 +15874,50 @@ trapping or setting ``errno``.
 When specified with the fast-math-flag 'afn', the result may be approximated
 using a less accurate calculation.
 
+
+'``llvm.sincos.*``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+This is an overloaded intrinsic. You can use ``llvm.sincos`` on any
+floating-point or vector of floating-point type. Not all targets support
+all types however.
+
+::
+
+      declare { float, float }          @llvm.sincos.f32(float  %Val)
+      declare { double, double }        @llvm.sincos.f64(double %Val)
+      declare { x86_fp80, x86_fp80 }    @llvm.sincos.f80(x86_fp80  %Val)
+      declare { fp128, fp128 }          @llvm.sincos.f128(fp128 %Val)
+      declare { ppc_fp128, ppc_fp128 }  @llvm.sincos.ppcf128(ppc_fp128  %Val)
+      declare { <4 x float>, <4 x float> } @llvm.sincos.v4f32(<4 x float>  %Val)
+
+Overview:
+"""""""""
+
+The '``llvm.sincos.*``' intrinsics returns the sine and cosine of the operand.
+
+Arguments:
+""""""""""
+
+The argument is a :ref:`floating-point <t_floating>` or :ref:`vector <t_vector>`
----------------
sdesmalen-arm wrote:

nit:
```suggestion
The argument is a :ref:`floating-point <t_floating>` value or :ref:`vector <t_vector>`
```

https://github.com/llvm/llvm-project/pull/109825