[flang-commits] [flang] [flang] IEEE_SCALB and SCALE - kind=2, kind=3 (PR #135374)

[via flang-commits]

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@@ -7593,12 +7593,46 @@ IntrinsicLibrary::genSameTypeAs(mlir::Type resultType,
 mlir::Value IntrinsicLibrary::genScale(mlir::Type resultType,
                                        llvm::ArrayRef<mlir::Value> args) {
   assert(args.size() == 2);
+  mlir::FloatType floatTy = mlir::dyn_cast<mlir::FloatType>(resultType);
+  if (!floatTy.isF16() && !floatTy.isBF16()) // kind=4,8,10,16
+    return builder.createConvert(
+        loc, resultType,
+        fir::runtime::genScale(builder, loc, args[0], args[1]));
 
-  mlir::Value realX = fir::getBase(args[0]);
-  mlir::Value intI = fir::getBase(args[1]);
-
-  return builder.createConvert(
-      loc, resultType, fir::runtime::genScale(builder, loc, realX, intI));
+  // Convert kind=2,3 arg X to kind=4. Convert kind=4 result back to kind=2,3.
+  mlir::Type i1Ty = builder.getI1Type();
+  mlir::Type f32Ty = mlir::Float32Type::get(builder.getContext());
+  mlir::Value result = builder.createConvert(
+      loc, resultType,
+      fir::runtime::genScale(
+          builder, loc, builder.createConvert(loc, f32Ty, args[0]), args[1]));
+
+  // kind=4 runtime::genScale call may not signal kind=2,3 exceptions.
+  // If X is finite and result is infinite, signal IEEE_OVERFLOW
+  // If X is finite and scale(result, -I) != X, signal IEEE_UNDERFLOW
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vdonaldson wrote:

I don't believe the core correctness of the results of these new kinds is affected by conversions between kinds 2, 3, and 4. I believe that level of correctness is automatically accounted for. I haven't attempted to look at detailed correctness with respect to rounding modes and very low level details of the implementation for either the existing kinds or the new kinds.

https://github.com/llvm/llvm-project/pull/135374