imask — LLVM 21.1.8 documentation

# imask

This operand is a mask which controls indexing mode for operands of subsequent instructions. Bits 0, 1 and 2 control indexing of src0, src1 and src2, while bit 3 controls indexing of dst. Value 1 enables indexing, and value 0 disables it.

> Bit | Meaning
> --- | ---
> 0 | Enables or disables src0 indexing.
> 1 | Enables or disables src1 indexing.
> 2 | Enables or disables src2 indexing.
> 3 | Enables or disables dst indexing.

This operand may be specified as one of the following:

- An integer_number or an absolute_expression. The value must be in the range from 0 to 15.

- A gpr_idx value which is described below.

  > Gpr_idx Value Syntax | Description
  > --- | ---
  > gpr_idx(<operand list>) | Enable indexing for the specified operands and disable it for the rest. Operand list is a comma-separated list of values which may include: SRC0 - enable src0 indexing. SRC1 - enable src1 indexing. SRC2 - enable src2 indexing. DST - enable dst indexing. Each of these values may be specified only once. Operand list may be empty; this syntax disables indexing for all operands.

Examples:

    s_set_gpr_idx_mode 0
    s_set_gpr_idx_mode gpr_idx()                        // the same as above

    s_set_gpr_idx_mode 15
    s_set_gpr_idx_mode gpr_idx(DST,SRC0,SRC1,SRC2)      // the same as above
    s_set_gpr_idx_mode gpr_idx(SRC0,SRC1,SRC2,DST)      // the same as above

    s_set_gpr_idx_mode gpr_idx(DST,SRC1)