waitcnt — LLVM 14.0.6 documentation

# waitcnt

Counts of outstanding instructions to wait for.

The bits of this operand have the following meaning:

> Bits | Description | Value Range
> --- | --- | ---
> 3:0 | VM_CNT: vector memory operations count. | 0..15
> 6:4 | EXP_CNT: export count. | 0..7
> 11:8 | LGKM_CNT: LDS, GDS, Constant and Message count. | 0..15

This operand may be specified as one of the following:

- An integer_number or an absolute_expression. The value must be in the range 0..0xFFFF.

- A combination of vmcnt, expcnt, lgkmcnt and other values described below.

  > Syntax | Description
  > --- | ---
  > vmcnt(<N>) | A VM_CNT value. N must not exceed the largest VM_CNT value.
  > expcnt(<N>) | An EXP_CNT value. N must not exceed the largest EXP_CNT value.
  > lgkmcnt(<N>) | An LGKM_CNT value. N must not exceed the largest LGKM_CNT value.
  > vmcnt_sat(<N>) | A VM_CNT value computed as min(N, the largest VM_CNT value).
  > expcnt_sat(<N>) | An EXP_CNT value computed as min(N, the largest EXP_CNT value).
  > lgkmcnt_sat(<N>) | An LGKM_CNT value computed as min(N, the largest LGKM_CNT value).

These values may be specified in any order. Spaces, ampersands and commas may be used as optional separators.

N is either an integer number or an absolute expression.

Examples:

    vm_cnt = 1
    exp_cnt = 2
    lgkm_cnt = 3
    cnt = vm_cnt | (exp_cnt << 4) | (lgkm_cnt << 8)

    s_waitcnt cnt
    s_waitcnt 1 | (2 << 4) | (3 << 8)                          // the same as above
    s_waitcnt vmcnt(1) expcnt(2) lgkmcnt(3)                    // the same as above
    s_waitcnt vmcnt(vm_cnt) expcnt(exp_cnt) lgkmcnt(lgkm_cnt)  // the same as above

    s_waitcnt vmcnt(1)
    s_waitcnt expcnt(2) lgkmcnt(3)
    s_waitcnt vmcnt(1), expcnt(2), lgkmcnt(3)
    s_waitcnt vmcnt(1) & lgkmcnt_sat(100) & expcnt(2)