Revert "[AutoDiff] Better diagnose non-differentiability for throwing functions (swiftlang#81669)"

This reverts commit bc94ac3.

Author: hamishknight

lib/SILOptimizer/Differentiation/PullbackCloner.cpp

@@ -1780,12 +1780,8 @@ class PullbackCloner::Implementation final
   void visitMoveValueInst(MoveValueInst *mvi) {
     switch (getTangentValueCategory(mvi)) {
     case SILValueCategory::Address:
-      LLVM_DEBUG(getADDebugStream() << "AutoDiff does not support move_value with "
-                 "SILValueCategory::Address");
-      getContext().emitNondifferentiabilityError(
-        mvi, getInvoker(), diag::autodiff_expression_not_differentiable_note);
-      errorOccurred = true;
-      return;
+      llvm::report_fatal_error("AutoDiff does not support move_value with "
+                               "SILValueCategory::Address");
     case SILValueCategory::Object:
       visitValueOwnershipInst(mvi, /*needZeroResAdj=*/true);
     }
@@ -3125,21 +3121,8 @@ void PullbackCloner::Implementation::visitSILBasicBlock(SILBasicBlock *bb) {
         break;
       }
       }
-    } else {
-      LLVM_DEBUG(getADDebugStream() <<
-                 "do not know how to handle this incoming bb argument");
-      if (auto term = bbArg->getSingleTerminator()) {
-        getContext().emitNondifferentiabilityError(term, getInvoker(),
-          diag::autodiff_expression_not_differentiable_note);
-      } else {
-        // This will be a bit confusing, but still better than nothing.
-        getContext().emitNondifferentiabilityError(bbArg, getInvoker(),
-          diag::autodiff_expression_not_differentiable_note);
-      }
-
-      errorOccurred = true;
-      return;
-    }
+    } else
+      llvm::report_fatal_error("do not know how to handle this incoming bb argument");
   }
 
   // 3. Build the pullback successor cases for the `switch_enum`

test/AutoDiff/SILOptimizer/differentiation_diagnostics.swift

@@ -46,17 +46,6 @@ func try_apply_rethrows(_ x: Float) -> Float {
   return x
 }
 
-// This generates `try_apply` which we do not know to handle yet, therefore
-// one should use a.differentialMap here. If / when differentiation of throwing
-// functions will be supported, we'd need to remove this diagnostics.
-// expected-error @+2 {{function is not differentiable}}
-// expected-note @+2 {{when differentiating this function definition}}
-@differentiable(reverse)
-func map_nondiff(_ a: [Float]) -> [Float] {
-  // expected-note @+1 {{expression is not differentiable}}
-  return a.map { $0 }
-}
-
 //===----------------------------------------------------------------------===//
 // Unreachable
 //===----------------------------------------------------------------------===//