@@ -5283,7 +5283,9 @@ Arithmetic-shift operand 1 left by a num
2, and store the result in operand 0. Here @var{m} is the mode of
operand 0 and operand 1; operand 2's mode is specified by the
instruction pattern, and the compiler will convert the operand to that
-mode before generating the instruction. The meaning of out-of-range shift
+mode before generating the instruction. The shift or rotate expander
+or instruction pattern should explicitly specify the mode of the operand 2,
+it should never be @code{VOIDmode}. The meaning of out-of-range shift
counts can optionally be specified by @code{TARGET_SHIFT_TRUNCATION_MASK}.
@xref{TARGET_SHIFT_TRUNCATION_MASK}. Operand 2 is always a scalar type.