Duplicate top operand stack word and put two down
Bytecode
Type | Description |
u1 | dup_x1 = 0x5A (90) |
Stack ..., word2, word1 => ..., word1, word2, word1
Description
Duplicates the top item on the stack and inserts the duplicate below
the second-from-top item. Both items must be single-word items.
The top word on the operand stack is duplicated and the copy inserted two words down in the operand stack.
The dup_x1 instruction must not be used unless each of word1 and word2 is a word that contains a 32-bit data type.
Except for restrictions preserving the integrity of 64-bit data types, the dup_x1 instruction operates on untyped words, ignoring the types of the data they contain.
This instruction cannot be used if either of item1 or item2 are two-word items. To duplicate a two-word item (a long or a double) you must use dup2, dup2_x1 or dup2_x2.