Stack manipulation

      ckheight       ckheight_n       dup       dup2
      dup_n       dup_word_n       local_alloc       pop
      pop2       pop_n       squash

ckheight
  · Operation Check the height of the stack
  · Format
ckheight
0
0
0
0
  · Direct Format
{ckheight}
0
  · Forms ckheight = 64 (0x40)
· Description Check that the stack has at least 8 words of space available for pushing values.
· Notes This instruction is used at the start of a method to check that that there is sufficient stack space to hold the local variables and temporary stack values used by the method.
The opcode is followed by 4 zero bytes so that this instruction has the same length as ckheight_n. This makes it easier to back-patch the height after translating the method.
· Exceptions System.StackOverflowException -- Raised if there is insufficient space available on the stack.

ckheight_n
  · Operation Check the height of the stack for N words of available space
  · Format
ckheight_n
N[4]
  · Direct Format
{ckheight_n}
N
  · Forms ckheight_n = 65 (0x41)
· Description Check that the stack has at least N words of space available for pushing values.
· Notes This instruction is used at the start of a method to check that that there is sufficient stack space to hold the local variables and temporary stack values used by the method.
· Exceptions System.StackOverflowException -- Raised if there is insufficient space available on the stack.

dup
  · Operation Duplicate the top of stack
  · Format
dup
  · Direct Format
{dup}
  · Forms dup = 56 (0x38)
  · Stack ..., value => ..., value, value
· Description Pop the single-word value from the stack, and then push it twice.

dup2
  · Operation Duplicate the top two stack words
  · Format
dup2
  · Direct Format
{dup2}
  · Forms dup2 = 57 (0x39)
  · Stack ..., value1, value2 => ..., value1, value2, value1, value2
· Description Pop the words value1 and value2 from the stack and then push them twice.

dup_n
  · Operation Duplicate the top N stack words
  · Format
dup_n
N[1]
wide
dup_n
N[4]
  · Direct Format
{dup_n}
N
  · Forms dup_n = 58 (0x3A)
  · Stack ..., value1, ..., valueN => ..., value1, ..., valueN, value1, ..., valueN
· Description Pop the top N words from the stack and then push them twice.
· Notes This is typically used for value type instances that are larger than 2 words in size.

dup_word_n
  · Operation Duplicate a stack word that is N words down the stack
  · Format
dup_word_n
N[1]
wide
dup_word_n
N[4]
  · Direct Format
{dup_word_n}
N
  · Forms dup_word_n = 59 (0x3B)
  · Stack ..., value, word1, ..., wordN => ..., value, word1, ..., wordN, value
· Description Retrieve the value that is N words down the stack and push it onto the top of the stack.

local_alloc
  · Operation Allocate local stack space
  · Format
prefix
local_alloc
  · Direct Format
{local_alloc}
  · Forms local_alloc = 255, 92 (0xFF, 0x5C)
  · Stack ..., size => ..., pointer
· Description Pop size from the stack as type uint, and then push a pointer to a block of memory of size bytes in size.
· Notes The block is not expected to last beyond the lifetime of the current method, but implementations may allocate longer-term memory if it is difficult to do direct stack allocation.
· Exceptions System.OutOfMemoryException -- Raised if there is insufficient memory to allocate the block.

pop
  · Operation Pop the top-most word from the stack
  · Format
pop
  · Direct Format
{pop}
  · Forms pop = 60 (0x3C)
  · Stack ..., value => ...
· Description Pop the single-word value from the stack.

pop2
  · Operation Pop the top two words from the stack
  · Format
pop2
  · Direct Format
{pop2}
  · Forms pop2 = 61 (0x3D)
  · Stack ..., value1, value2 => ...
· Description Pop the two stack words value1 and value2 from the stack.

pop_n
  · Operation Pop the top N words from the stack
  · Format
pop_n
N[1]
wide
pop_n
N[4]
  · Direct Format
{pop_n}
N
  · Forms pop_n = 62 (0x3E)
  · Stack ..., value1, ..., valueN => ...
· Description Pop the top N stack words from the stack.

squash
  · Operation Squash a number of words out of the stack
  · Format
squash
N[1]
M[1]
wide
squash
N[4]
M[4]
  · Direct Format
{squash}
N
M
  · Forms squash = 63 (0x3F)
  · Stack ..., word1, ..., wordM, value1, ..., valueN => ..., value1, ..., valueN
· Description Remove the M words from the stack, N words down the stack.