[flang] [llvm] [flang] ieee_denorm (PR #132307)

[via llvm-commits]

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@@ -5805,24 +5806,61 @@ mlir::Value IntrinsicLibrary::genIeeeSignbit(mlir::Type resultType,
 fir::ExtendedValue
 IntrinsicLibrary::genIeeeSupportFlag(mlir::Type resultType,
                                      llvm::ArrayRef<fir::ExtendedValue> args) {
-  // Check if a floating point exception flag is supported. A flag is
-  // supported either for all type kinds or none. An optional kind argument X
-  // is therefore ignored. Standard flags are all supported. The nonstandard
-  // DENORM extension is not supported, at least for now.
+  // Check if a floating point exception flag is supported.
   assert(args.size() == 1 || args.size() == 2);
+  mlir::Type i1Ty = builder.getI1Type();
+  mlir::Type i32Ty = builder.getIntegerType(32);
   auto [fieldRef, fieldTy] = getFieldRef(builder, loc, getBase(args[0]));
   mlir::Value flag = builder.create<fir::LoadOp>(loc, fieldRef);
-  mlir::Value mask = builder.createIntegerConstant( // values are powers of 2
+  mlir::Value standardFlagMask = builder.createIntegerConstant(
       loc, fieldTy,
       _FORTRAN_RUNTIME_IEEE_INVALID | _FORTRAN_RUNTIME_IEEE_DIVIDE_BY_ZERO |
           _FORTRAN_RUNTIME_IEEE_OVERFLOW | _FORTRAN_RUNTIME_IEEE_UNDERFLOW |
           _FORTRAN_RUNTIME_IEEE_INEXACT);
-  return builder.createConvert(
-      loc, resultType,
-      builder.create<mlir::arith::CmpIOp>(
-          loc, mlir::arith::CmpIPredicate::ne,
-          builder.create<mlir::arith::AndIOp>(loc, flag, mask),
-          builder.createIntegerConstant(loc, fieldTy, 0)));
+  mlir::Value isStandardFlag = builder.create<mlir::arith::CmpIOp>(
+      loc, mlir::arith::CmpIPredicate::ne,
+      builder.create<mlir::arith::AndIOp>(loc, flag, standardFlagMask),
+      builder.createIntegerConstant(loc, fieldTy, 0));
+  fir::IfOp ifOp = builder.create<fir::IfOp>(loc, i1Ty, isStandardFlag,
+                                             /*withElseRegion=*/true);
+  // Standard flags are supported.
+  builder.setInsertionPointToStart(&ifOp.getThenRegion().front());
+  builder.create<fir::ResultOp>(loc, builder.createBool(loc, true));
+
+  // TargetCharacteristics information for the nonstandard ieee_denorm flag
+  // is not available here. So use a runtime check restricted to possibly
+  // supported kinds.
+  builder.setInsertionPointToStart(&ifOp.getElseRegion().front());
+  bool mayBeSupported = false;
+  if (mlir::Value arg1 = getBase(args[1])) {
+    mlir::Type arg1Ty = arg1.getType();
+    if (fir::ReferenceType refTy = mlir::dyn_cast<fir::ReferenceType>(arg1Ty))
+      arg1Ty = refTy.getEleTy();
+    switch (mlir::dyn_cast<mlir::FloatType>(arg1Ty).getWidth()) {
+    case 16:
+      mayBeSupported = arg1Ty.isBF16(); // kind=3
+      break;
+    case 32: // kind=4
+    case 64: // kind=8
+      mayBeSupported = true;
+      break;
+    }
+  }
+  if (mayBeSupported) {
+    mlir::Value result = builder.create<mlir::arith::AndIOp>(
+        loc,
+        builder.create<mlir::arith::CmpIOp>(
+            loc, mlir::arith::CmpIPredicate::eq, flag,
+            builder.createIntegerConstant(loc, fieldTy,
+                                          _FORTRAN_RUNTIME_IEEE_DENORM)),
+        fir::runtime::genSupportHalting(
+            builder, loc, builder.create<fir::ConvertOp>(loc, i32Ty, flag)));
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jeanPerier wrote:

nit: please assign one of the two calls generating value to some mlir::Value so that the IR generation is deterministic.

https://github.com/llvm/llvm-project/pull/132307