[flang] Use i16 instead of i2 for cmdstat (llvm#91647)

The code for preparing cmdstat was generating an i2 constant with value
0, casting it, and then storing it into i16 storage. Just generate i16
constant directly.

Author: razvanlupusoru

flang/lib/Optimizer/Builder/IntrinsicCall.cpp

@@ -6306,11 +6306,9 @@ void IntrinsicLibrary::genSystem(llvm::ArrayRef<fir::ExtendedValue> args) {
   // Create a dummmy cmdstat to prevent EXECUTE_COMMAND_LINE terminate itself
   // when cmdstat is assigned with a non-zero value but not present
   mlir::Value tempValue =
-      builder.createIntegerConstant(loc, builder.getI2Type(), 0);
+      builder.createIntegerConstant(loc, builder.getI16Type(), 0);
   mlir::Value temp = builder.createTemporary(loc, builder.getI16Type());
-  mlir::Value castVal =
-      builder.createConvert(loc, builder.getI16Type(), tempValue);
-  builder.create<fir::StoreOp>(loc, castVal, temp);
+  builder.create<fir::StoreOp>(loc, tempValue, temp);
   mlir::Value cmdstatBox = builder.createBox(loc, temp);
 
   mlir::Value cmdmsgBox =

flang/test/Lower/Intrinsics/system-optional.f90

@@ -19,8 +19,7 @@ subroutine all_args(command, exitstat)
 ! CHECK-NEXT:    %[[absentIntBox:.*]] = fir.absent !fir.box<i32>
 ! CHECK-NEXT:    %[[exitstatRealBox:.*]] = arith.select %[[exitstatIsPresent]], %[[exitstatBox]], %[[absentIntBox]] : !fir.box<i32>
 ! CHECK-NEXT:    %[[true:.*]] = arith.constant true
-! CHECK-NEXT:    %[[c0_i2:.*]] = arith.constant 0 : i2
-! CHECK-NEXT:    %[[c0_i16:.*]] = fir.convert %[[c0_i2]] : (i2) -> i16
+! CHECK-NEXT:    %[[c0_i16:.*]] = arith.constant 0 : i16
 ! CHECK-NEXT:    fir.store %[[c0_i16]] to %[[cmdstatVal]] : !fir.ref<i16>
 ! CHECK-NEXT:    %[[cmdstatBox:.*]] = fir.embox %[[cmdstatVal]] : (!fir.ref<i16>) -> !fir.box<i16>
 ! CHECK-NEXT:    %[[absentBox:.*]] = fir.absent !fir.box<none>

flang/test/Lower/Intrinsics/system.f90

@@ -15,8 +15,7 @@ subroutine all_args(command, exitstat)
 ! CHECK-NEXT:   %[[commandBox:.*]] = fir.embox %[[commandDeclare]]#1 typeparams %[[commandUnbox]]#1 : (!fir.ref<!fir.char<1,?>>, index) -> !fir.box<!fir.char<1,?>>
 ! CHECK-NEXT:   %[[exitstatBox:.*]] = fir.embox %[[exitstatDeclare]]#1 : (!fir.ref<i32>) -> !fir.box<i32>
 ! CHECK-NEXT:   %[[true:.*]] = arith.constant true
-! CHECK-NEXT:   %[[c0_i2:.*]] = arith.constant 0 : i2
-! CHECK-NEXT:   %[[c0_i16:.*]] = fir.convert %[[c0_i2]] : (i2) -> i16
+! CHECK-NEXT:   %[[c0_i16:.*]] = arith.constant 0 : i16
 ! CHECK-NEXT:   fir.store %[[c0_i16]] to %[[cmdstatVal]] : !fir.ref<i16>
 ! CHECK-NEXT:   %[[cmdstatBox:.*]] = fir.embox %[[cmdstatVal]] : (!fir.ref<i16>) -> !fir.box<i16>
 ! CHECK-NEXT:   %[[absentBox:.*]] = fir.absent !fir.box<none>
@@ -41,8 +40,7 @@ subroutine only_command(command)
 ! CHECK-NEXT:   %[[commandBox:.*]] = fir.embox %[[commandDeclare]]#1 typeparams %[[commandUnbox]]#1 : (!fir.ref<!fir.char<1,?>>, index) -> !fir.box<!fir.char<1,?>>
 ! CHECK-NEXT:   %[[true:.*]] = arith.constant true
 ! CHECK-NEXT:   %[[absentBox:.*]] = fir.absent !fir.box<none>
-! CHECK-NEXT:   %[[c0_i2:.*]] = arith.constant 0 : i2
-! CHECK-NEXT:   %[[c0_i16:.*]] = fir.convert %[[c0_i2]] : (i2) -> i16
+! CHECK-NEXT:   %[[c0_i16:.*]] = arith.constant 0 : i16
 ! CHECK-NEXT:   fir.store %[[c0_i16]] to %[[cmdstatVal]] : !fir.ref<i16>
 ! CHECK-NEXT:   %[[cmdstatBox:.*]] = fir.embox %[[cmdstatVal]] : (!fir.ref<i16>) -> !fir.box<i16>
 ! CHECK-NEXT:   %[[absentBox2:.*]] = fir.absent !fir.box<none>