Various extensions to the vectorizer

Includes additions to the AstVectorizer:

• Vectorize assignments to vector symbols
• Vectorize loops nested within the vectorization axis if all bounds are independent of the axis
• Vectorize array subscripts if all indices and the array expression are independent of the axis
• Handle empty nodes (e.g. comments)

Additions to the x86 instruction set:

• Intrinsics for basic math functions (log, abs, etc.)
• Type conversions

And to the SelectIntrinsics pass:

• Add option to implemenet type conversions using __builtin_convertvector which is supported by most compilers instead of inserting intrinsics. Useful because not all conversions are supported natively on all CPUs.

src/pystencils/backend/platforms/x86.py

@@ -193,10 +193,15 @@ class X86VectorCpu(GenericVectorCpu):
                 | MathFunctions.ATan
                 | MathFunctions.ATan2
                 | MathFunctions.Pow
-                | MathFunctions.Floor
-                | MathFunctions.Ceil
-            ) if vtype.is_float():
+            ):
+                raise MaterializationError(
+                    "Trigonometry, exp, log, and pow require SVML."
+                )
+
+            case MathFunctions.Floor | MathFunctions.Ceil if vtype.is_float():
                 opstr = expr.function.func.function_name
+                if vtype.width > 256:
+                    raise MaterializationError("512bit ceil/floor require SVML.")
 
             case MathFunctions.Min | MathFunctions.Max:
                 opstr = expr.function.func.function_name
@@ -234,10 +239,10 @@ class X86VectorCpu(GenericVectorCpu):
 
                         return func(neg_zero, op)
 
-                    case _:
-                        raise MaterializationError(
-                            f"x86/{self} does not support abs on type {vtype}."
-                        )
+            case _:
+                raise MaterializationError(
+                    f"x86/{self} does not support {expr.function.func.function_name} on type {vtype}."
+                )
 
         if expr.function.func in [
             MathFunctions.ATan2,