tablegen: Add StaticSelect to select based on static condition (#2206)

* tablegen: Add StaticIf to select based on static condition

* rename to StaticSelect and implement SelectIfActive and SelectIfComplex
with it

* define for llvm

* put vector mode for LLVM back

* basic use analysis

* StaticSelect use analysis

* fixup

---------

Co-authored-by: William S. Moses <[email protected]>

Author: Pangoraw

enzyme/Enzyme/InstructionDerivatives.td

@@ -13,6 +13,11 @@ class ConstantFP<string val> : Operation</*primal*/0, /*shadow*/0> {
   string value = val;
 }
 
+class StaticSelect<string condition_> : Operation</*primal*/0, /*shadow*/0, /*custom*/0> {
+  string condition = condition_;
+}
+
+def SelectIfActive : StaticSelect<"!gutils->isConstantValue(imVal)">;
 
 class Attribute<string name_> {
   string name = name_;
@@ -62,9 +67,6 @@ class Inst<string mnemonic>  : Operation</*primal*/1, /*shadow*/0> {
 def TypeOf : Operation</*primal*/0, /*shadow*/0> {
 }
 def VectorSize : Operation</*primal*/0, /*shadow*/0> {
-}
-def SelectIfActive : Operation</*primal*/0, /*shadow*/0, /*custom*/1> {
-  
 }
 
 // Define ops to rewrite.

enzyme/Enzyme/MLIR/Implementations/Common.td

@@ -86,10 +86,20 @@ def DiffeRet : DiffeRetIndex<[-1]>;
 def Shadow : Operation</*primal*/0, /*shadow*/1> {
 }
 
-class GlobalExpr<bit uses_primal, bit uses_shadow, string val> : Operation<uses_primal, uses_shadow>{
+class GlobalExpr<bit uses_primal, bit uses_shadow, string val> : Operation<uses_primal, uses_shadow> {
   string value = val;
 }
 
+// Class for a dag operator that generates either a or b
+// It can then be used with a two or three arguments.
+// The two arguments version is (StaticSelect a, b)
+// The three arguments version accepts a name as a first argument
+// which is then available in the condition as a `Value` under the
+// variable `imVal`.
+class StaticSelect<string condition_> : Operation</*usesPrimal*/0, /*usesShadow*/0, /*usesCustom*/0> {
+  string condition = condition_;
+}
+
 class Inst<string mnemonic, string dialect_, string postop_="">  : Operation</*primal*/1, /*shadow*/0> {
   string name = mnemonic;
   string dialect = dialect_;
@@ -99,13 +109,14 @@ class Inst<string mnemonic, string dialect_, string postop_="">  : Operation</*p
 def Op {
 }
 
-def SelectIfActive : Operation</*primal*/0, /*shadow*/0, /*custom*/1> {
-
-}
-
-def SelectIfComplex : Operation</*primal*/1, /*shadow*/0, /*custom*/0> {
+def SelectIfActive : StaticSelect<"!gutils->isConstantValue(imVal)">;
 
-}
+def SelectIfComplex : StaticSelect<[{
+  auto ty = imVal.getType();
+  ty.isa<ComplexType>() ||
+    ty.isa<TensorType>() &&
+    ty.cast<TensorType>().getElementType().isa<ComplexType>();
+}]>;
 
 class ConstantFP<string val, string dialect_, string op_, string type_=""> : Operation</*primal*/0, /*shadow*/0> {
   string value = val;