hwregΒΆ

Bits of a hardware register being accessed.

The bits of this operand have the following meaning:

Bits Description Value Range
5:0 Register id. 0..63
10:6 First bit offset. 0..31
15:11 Size in bits. 1..32

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.

  • An hwreg value described below.

    Hwreg Value Syntax Description
    hwreg({0..63}) All bits of a register indicated by its id.
    hwreg(<name>) All bits of a register indicated by its name.
    hwreg({0..63}, {0..31}, {1..32}) Register bits indicated by register id, first bit offset and size.
    hwreg(<name>, {0..31}, {1..32}) Register bits indicated by register name, first bit offset and size.

Numeric values may be specified as positive integer numbers or absolute expressions.

Defined register names include:

Name Description
HW_REG_MODE Shader writeable mode bits.
HW_REG_STATUS Shader read-only status.
HW_REG_TRAPSTS Trap status.
HW_REG_HW_ID Id of wave, simd, compute unit, etc.
HW_REG_GPR_ALLOC Per-wave SGPR and VGPR allocation.
HW_REG_LDS_ALLOC Per-wave LDS allocation.
HW_REG_IB_STS Counters of outstanding instructions.
HW_REG_SH_MEM_BASES Memory aperture.

Examples:

reg = 1
offset = 2
size = 4
hwreg_enc = reg | (offset << 6) | ((size - 1) << 11)

s_getreg_b32 s2, 0x1881
s_getreg_b32 s2, hwreg_enc                     // the same as above
s_getreg_b32 s2, hwreg(1, 2, 4)                // the same as above
s_getreg_b32 s2, hwreg(reg, offset, size)      // the same as above

s_getreg_b32 s2, hwreg(15)
s_getreg_b32 s2, hwreg(51, 1, 31)
s_getreg_b32 s2, hwreg(HW_REG_LDS_ALLOC, 0, 1)