[MLIR] Add read-only reverse mode arg

enzyme/Enzyme/MLIR/Implementations/ArithDerivatives.td

@@ -31,3 +31,9 @@ def : MLIRDerivative<"arith", "DivFOp", (Op $x, $y),
  ],
  (CheckedDivF (SubF (SelectIfActive $x, (MulF (Shadow $x), $y), (ConstantFP<"0","arith", "ConstantOp"> $x)), (SelectIfActive $y, (MulF (Shadow $y), $x), (ConstantFP<"0","arith","ConstantOp"> $y))), (MulF $y, $y))
  >;
+
+def ExtF : ArithInst<"ExtFOp">;
+def TruncF : ArithInst<"TruncFOp">;
+
+def : ReadOnlyIdentityOp<"arith", "TruncFOp", [0], (Op $x), [(ExtF (TypeOf $x), (DiffeRet))]>;
+def : ReadOnlyIdentityOp<"arith", "ExtFOp", [0], (Op $x), [(TruncF (TypeOf $x), (DiffeRet))]>;

enzyme/Enzyme/MLIR/Implementations/Common.td

@@ -17,14 +17,21 @@ class ControlFlowOp<string dialect_, string opName_, string impl_> {
  string impl = impl_;
 }
 
-class MemoryIdentityOp<string dialect_, string opName_, list<int> ptrargs_, list<int> storedargs_ = []> {
+
+def Unimplemented {
+
+}
+
+class MemoryIdentityOp<string dialect_, string opName_, list<int> ptrargs_, list<int> storedargs_ = [], dag patternToMatch=(Unimplemented), list<dag> reverse_ = []> {
  string dialect = dialect_;
  string opName = opName_;
+ dag PatternToMatch = patternToMatch;
  list<int> ptrargs = ptrargs_;
  list<int> storedargs = storedargs_;
+ list<dag> reverse = reverse_;
 }
 
-class ReadOnlyIdentityOp<string dialect_, string opName_, list<int> ptrargs_> : MemoryIdentityOp<dialect_, opName_, ptrargs_>;
+class ReadOnlyIdentityOp<string dialect_, string opName_, list<int> ptrargs_, dag patternToMatch=(Unimplemented), list<dag> reverse_ = []> : MemoryIdentityOp<dialect_, opName_, ptrargs_, [], patternToMatch, reverse_>;
 
 class ReturnOp<string dialect_, string opName_> {
  string dialect = dialect_;
@@ -94,6 +101,9 @@ class ConstantFP<string val, string dialect_, string op_, string type_=""> : Ope
 
 def ResultTypes : GlobalExpr</*needsprimal*/0, /*needsshadow*/0, "op->getResultTypes()">;
 
+def TypeOf : Operation</*primal*/0, /*shadow*/0> {
+}
+
 class ArithInst<string m> : Inst<m, "arith">;
 class MathInst<string m> : Inst<m, "math">;
 

enzyme/test/MLIR/ForwardMode/trunc.mlir

@@ -0,0 +1,18 @@
+// RUN: %eopt --enzyme %s | FileCheck %s
+
+module {
+ func.func @f(%x : f64) -> f32 {
+ %y = arith.truncf %x : f64 to f32
+ return %y : f32
+ }
+ func.func @dsq(%x : f64, %dx : f64) -> f32 {
+ %r = enzyme.fwddiff @f(%x, %dx) { activity=[#enzyme<activity enzyme_dup>] } : (f64, f64) -> (f32)
+ return %r : f32
+ }
+}
+
+// CHECK: func.func private @fwddiffef(%[[arg0:.+]]: f64, %[[arg1:.+]]: f64) -> f32 {
+// CHECK-NEXT: %[[dy:.+]] = arith.truncf %[[arg1]] : f64 to f32
+// CHECK-NEXT: %[[y:.+]] = arith.truncf %[[arg0]] : f64 to f32
+// CHECK-NEXT: return %[[dy]] : f32
+// CHECK-NEXT: }

enzyme/test/MLIR/ReverseMode/trunc.mlir

@@ -0,0 +1,18 @@
+// RUN: %eopt --enzyme --canonicalize --remove-unnecessary-enzyme-ops --canonicalize --enzyme-simplify-math --cse %s | FileCheck %s --check-prefix=FIN
+
+module {
+ func.func @f(%x: f64) -> f32 {
+ %next = arith.truncf %x : f64 to f32
+ return %next : f32
+ }
+
+ func.func @dsquare(%x: f64, %dr: f32) -> f64 {
+ %r = enzyme.autodiff @f(%x, %dr) { activity=[#enzyme<activity enzyme_out>] } : (f64, f32) -> f64
+ return %r : f64
+ }
+}
+
+// FIN: func.func private @diffef(%[[x:.+]]: f64, %[[dx:.+]]: f32) -> f64 {
+// FIN-NEXT: %[[res:.+]] = arith.extf %[[dx]] : f32 to f64
+// FIN-NEXT: return %[[res]] : f64
+// FIN-NEXT: }