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llvm-mirror/docs/AMDGPUModifierSyntax.rst
Dmitry Preobrazhensky ebbe05934d [AMDGPU][MC][DOC] Updated AMD GPU assembler description. 
Summary of changes:
- Updated to reflect recent changes in assembler;
- Minor bugfixing and improvements.

llvm-svn: 372857
2019-09-25 12:38:35 +00:00

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======================================
Syntax of AMDGPU Instruction Modifiers
======================================
.. contents::
:local:
Conventions
===========
The following notation is used throughout this document:
=================== =============================================================
Notation Description
=================== =============================================================
{0..N} Any integer value in the range from 0 to N (inclusive).
<x> Syntax and meaning of *x* is explained elsewhere.
=================== =============================================================
.. _amdgpu_syn_modifiers:
Modifiers
=========
DS Modifiers
------------
.. _amdgpu_synid_ds_offset8:
offset8
~~~~~~~
Specifies an immediate unsigned 8-bit offset, in bytes. The default value is 0.
Used with DS instructions which have 2 addresses.
=================== ====================================================================
Syntax Description
=================== ====================================================================
offset:{0..0xFF} Specifies an unsigned 8-bit offset as a positive
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
=================== ====================================================================
Examples:
.. parsed-literal::
offset:0xff
offset:2-x
offset:-x-y
.. _amdgpu_synid_ds_offset16:
offset16
~~~~~~~~
Specifies an immediate unsigned 16-bit offset, in bytes. The default value is 0.
Used with DS instructions which have 1 address.
==================== ====================================================================
Syntax Description
==================== ====================================================================
offset:{0..0xFFFF} Specifies an unsigned 16-bit offset as a positive
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
==================== ====================================================================
Examples:
.. parsed-literal::
offset:65535
offset:0xffff
offset:-x-y
.. _amdgpu_synid_sw_offset16:
swizzle pattern
~~~~~~~~~~~~~~~
This is a special modifier which may be used with *ds_swizzle_b32* instruction only.
It specifies a swizzle pattern in numeric or symbolic form. The default value is 0.
See AMD documentation for more information.
======================================================= ===========================================================
Syntax Description
======================================================= ===========================================================
offset:{0..0xFFFF} Specifies a 16-bit swizzle pattern.
offset:swizzle(QUAD_PERM,{0..3},{0..3},{0..3},{0..3}) Specifies a quad permute mode pattern
Each number is a lane *id*.
offset:swizzle(BITMASK_PERM, "<mask>") Specifies a bitmask permute mode pattern.
The pattern converts a 5-bit lane *id* to another
lane *id* with which the lane interacts.
*mask* is a 5 character sequence which
specifies how to transform the bits of the
lane *id*.
The following characters are allowed:
* "0" - set bit to 0.
* "1" - set bit to 1.
* "p" - preserve bit.
* "i" - inverse bit.
offset:swizzle(BROADCAST,{2..32},{0..N}) Specifies a broadcast mode.
Broadcasts the value of any particular lane to
all lanes in its group.
The first numeric parameter is a group
size and must be equal to 2, 4, 8, 16 or 32.
The second numeric parameter is an index of the
lane being broadcasted.
The index must not exceed group size.
offset:swizzle(SWAP,{1..16}) Specifies a swap mode.
Swaps the neighboring groups of
1, 2, 4, 8 or 16 lanes.
offset:swizzle(REVERSE,{2..32}) Specifies a reverse mode.
Reverses the lanes for groups of 2, 4, 8, 16 or 32 lanes.
======================================================= ===========================================================
Note: numeric values may be specified as either :ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
offset:255
offset:0xffff
offset:swizzle(QUAD_PERM, 0, 1, 2, 3)
offset:swizzle(BITMASK_PERM, "01pi0")
offset:swizzle(BROADCAST, 2, 0)
offset:swizzle(SWAP, 8)
offset:swizzle(REVERSE, 30 + 2)
.. _amdgpu_synid_gds:
gds
~~~
Specifies whether to use GDS or LDS memory (LDS is the default).
======================================== ================================================
Syntax Description
======================================== ================================================
gds Use GDS memory.
======================================== ================================================
EXP Modifiers
-------------
.. _amdgpu_synid_done:
done
~~~~
Specifies if this is the last export from the shader to the target. By default,
*exp* instruction does not finish an export sequence.
======================================== ================================================
Syntax Description
======================================== ================================================
done Indicates the last export operation.
======================================== ================================================
.. _amdgpu_synid_compr:
compr
~~~~~
Indicates if the data are compressed (data are not compressed by default).
======================================== ================================================
Syntax Description
======================================== ================================================
compr Data are compressed.
======================================== ================================================
.. _amdgpu_synid_vm:
vm
~~
Specifies valid mask flag state (off by default).
======================================== ================================================
Syntax Description
======================================== ================================================
vm Set valid mask flag.
======================================== ================================================
FLAT Modifiers
--------------
.. _amdgpu_synid_flat_offset12:
offset12
~~~~~~~~
Specifies an immediate unsigned 12-bit offset, in bytes. The default value is 0.
Cannot be used with *global/scratch* opcodes. GFX9 only.
================= ====================================================================
Syntax Description
================= ====================================================================
offset:{0..4095} Specifies a 12-bit unsigned offset as a positive
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
================= ====================================================================
Examples:
.. parsed-literal::
offset:4095
offset:x-0xff
.. _amdgpu_synid_flat_offset13s:
offset13s
~~~~~~~~~
Specifies an immediate signed 13-bit offset, in bytes. The default value is 0.
Can be used with *global/scratch* opcodes only. GFX9 only.
===================== ====================================================================
Syntax Description
===================== ====================================================================
offset:{-4096..4095} Specifies a 13-bit signed offset as an
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
===================== ====================================================================
Examples:
.. parsed-literal::
offset:-4000
offset:0x10
offset:-x
.. _amdgpu_synid_flat_offset12s:
offset12s
~~~~~~~~~
Specifies an immediate signed 12-bit offset, in bytes. The default value is 0.
Can be used with *global/scratch* opcodes only.
GFX10 only.
===================== ====================================================================
Syntax Description
===================== ====================================================================
offset:{-2048..2047} Specifies a 12-bit signed offset as an
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
===================== ====================================================================
Examples:
.. parsed-literal::
offset:-2000
offset:0x10
offset:-x+y
.. _amdgpu_synid_flat_offset11:
offset11
~~~~~~~~
Specifies an immediate unsigned 11-bit offset, in bytes. The default value is 0.
Cannot be used with *global/scratch* opcodes.
GFX10 only.
================= ====================================================================
Syntax Description
================= ====================================================================
offset:{0..2047} Specifies an 11-bit unsigned offset as a positive
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
================= ====================================================================
Examples:
.. parsed-literal::
offset:2047
offset:x+0xff
dlc
~~~
See a description :ref:`here<amdgpu_synid_dlc>`. GFX10 only.
glc
~~~
See a description :ref:`here<amdgpu_synid_glc>`.
lds
~~~
See a description :ref:`here<amdgpu_synid_lds>`. GFX10 only.
slc
~~~
See a description :ref:`here<amdgpu_synid_slc>`.
tfe
~~~
See a description :ref:`here<amdgpu_synid_tfe>`.
nv
~~
See a description :ref:`here<amdgpu_synid_nv>`.
MIMG Modifiers
--------------
.. _amdgpu_synid_dmask:
dmask
~~~~~
Specifies which channels (image components) are used by the operation. By default, no channels
are used.
=============== ====================================================================
Syntax Description
=============== ====================================================================
dmask:{0..15} Specifies image channels as a positive
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
Each bit corresponds to one of 4 image components (RGBA).
If the specified bit value is 0, the component is not used,
value 1 means that the component is used.
=============== ====================================================================
This modifier has some limitations depending on instruction kind:
=================================================== ========================
Instruction Kind Valid dmask Values
=================================================== ========================
32-bit atomic *cmpswap* 0x3
32-bit atomic instructions except for *cmpswap* 0x1
64-bit atomic *cmpswap* 0xF
64-bit atomic instructions except for *cmpswap* 0x3
*gather4* 0x1, 0x2, 0x4, 0x8
Other instructions any value
=================================================== ========================
Examples:
.. parsed-literal::
dmask:0xf
dmask:0b1111
dmask:x|y|z
.. _amdgpu_synid_unorm:
unorm
~~~~~
Specifies whether the address is normalized or not (the address is normalized by default).
======================== ========================================
Syntax Description
======================== ========================================
unorm Force the address to be unnormalized.
======================== ========================================
glc
~~~
See a description :ref:`here<amdgpu_synid_glc>`.
slc
~~~
See a description :ref:`here<amdgpu_synid_slc>`.
.. _amdgpu_synid_r128:
r128
~~~~
Specifies texture resource size. The default size is 256 bits.
GFX7, GFX8 and GFX10 only.
=================== ================================================
Syntax Description
=================== ================================================
r128 Specifies 128 bits texture resource size.
=================== ================================================
.. WARNING:: Using this modifier should descrease *rsrc* operand size from 8 to 4 dwords, but assembler does not currently support this feature.
tfe
~~~
See a description :ref:`here<amdgpu_synid_tfe>`.
.. _amdgpu_synid_lwe:
lwe
~~~
Specifies LOD warning status (LOD warning is disabled by default).
======================================== ================================================
Syntax Description
======================================== ================================================
lwe Enables LOD warning.
======================================== ================================================
.. _amdgpu_synid_da:
da
~~
Specifies if an array index must be sent to TA. By default, array index is not sent.
======================================== ================================================
Syntax Description
======================================== ================================================
da Send an array-index to TA.
======================================== ================================================
.. _amdgpu_synid_d16:
d16
~~~
Specifies data size: 16 or 32 bits (32 bits by default). Not supported by GFX7.
======================================== ================================================
Syntax Description
======================================== ================================================
d16 Enables 16-bits data mode.
On loads, convert data in memory to 16-bit
format before storing it in VGPRs.
For stores, convert 16-bit data in VGPRs to
32 bits before going to memory.
Note that GFX8.0 does not support data packing.
Each 16-bit data element occupies 1 VGPR.
GFX8.1, GFX9 and GFX10 support data packing.
Each pair of 16-bit data elements
occupies 1 VGPR.
======================================== ================================================
.. _amdgpu_synid_a16:
a16
~~~
Specifies size of image address components: 16 or 32 bits (32 bits by default).
GFX9 and GFX10 only.
======================================== ================================================
Syntax Description
======================================== ================================================
a16 Enables 16-bits image address components.
======================================== ================================================
.. _amdgpu_synid_dim:
dim
~~~
Specifies surface dimension. This is a mandatory modifier. There is no default value.
GFX10 only.
=============================== =========================================================
Syntax Description
=============================== =========================================================
dim:1D One-dimensional image.
dim:2D Two-dimensional image.
dim:3D Three-dimensional image.
dim:CUBE Cubemap array.
dim:1D_ARRAY One-dimensional image array.
dim:2D_ARRAY Two-dimensional image array.
dim:2D_MSAA Two-dimensional multi-sample auto-aliasing image.
dim:2D_MSAA_ARRAY Two-dimensional multi-sample auto-aliasing image array.
=============================== =========================================================
The following table defines an alternative syntax which is supported
for compatibility with SP3 assembler:
=============================== =========================================================
Syntax Description
=============================== =========================================================
dim:SQ_RSRC_IMG_1D One-dimensional image.
dim:SQ_RSRC_IMG_2D Two-dimensional image.
dim:SQ_RSRC_IMG_3D Three-dimensional image.
dim:SQ_RSRC_IMG_CUBE Cubemap array.
dim:SQ_RSRC_IMG_1D_ARRAY One-dimensional image array.
dim:SQ_RSRC_IMG_2D_ARRAY Two-dimensional image array.
dim:SQ_RSRC_IMG_2D_MSAA Two-dimensional multi-sample auto-aliasing image.
dim:SQ_RSRC_IMG_2D_MSAA_ARRAY Two-dimensional multi-sample auto-aliasing image array.
=============================== =========================================================
dlc
~~~
See a description :ref:`here<amdgpu_synid_dlc>`. GFX10 only.
Miscellaneous Modifiers
-----------------------
.. _amdgpu_synid_dlc:
dlc
~~~
Controls device level cache policy for memory operations. Used for synchronization.
When specified, forces operation to bypass device level cache making the operation device
level coherent. By default, instructions use device level cache.
GFX10 only.
======================================== ================================================
Syntax Description
======================================== ================================================
dlc Bypass device level cache.
======================================== ================================================
.. _amdgpu_synid_glc:
glc
~~~
This modifier has different meaning for loads, stores, and atomic operations.
The default value is off (0).
See AMD documentation for details.
======================================== ================================================
Syntax Description
======================================== ================================================
glc Set glc bit to 1.
======================================== ================================================
.. _amdgpu_synid_lds:
lds
~~~
Specifies where to store the result: VGPRs or LDS (VGPRs by default).
======================================== ===========================
Syntax Description
======================================== ===========================
lds Store result in LDS.
======================================== ===========================
.. _amdgpu_synid_nv:
nv
~~
Specifies if instruction is operating on non-volatile memory. By default, memory is volatile.
GFX9 only.
======================================== ================================================
Syntax Description
======================================== ================================================
nv Indicates that instruction operates on
non-volatile memory.
======================================== ================================================
.. _amdgpu_synid_slc:
slc
~~~
Specifies cache policy. The default value is off (0).
See AMD documentation for details.
======================================== ================================================
Syntax Description
======================================== ================================================
slc Set slc bit to 1.
======================================== ================================================
.. _amdgpu_synid_tfe:
tfe
~~~
Controls access to partially resident textures. The default value is off (0).
See AMD documentation for details.
======================================== ================================================
Syntax Description
======================================== ================================================
tfe Set tfe bit to 1.
======================================== ================================================
MUBUF/MTBUF Modifiers
---------------------
.. _amdgpu_synid_idxen:
idxen
~~~~~
Specifies whether address components include an index. By default, no components are used.
Can be used together with :ref:`offen<amdgpu_synid_offen>`.
Cannot be used with :ref:`addr64<amdgpu_synid_addr64>`.
======================================== ================================================
Syntax Description
======================================== ================================================
idxen Address components include an index.
======================================== ================================================
.. _amdgpu_synid_offen:
offen
~~~~~
Specifies whether address components include an offset. By default, no components are used.
Can be used together with :ref:`idxen<amdgpu_synid_idxen>`.
Cannot be used with :ref:`addr64<amdgpu_synid_addr64>`.
======================================== ================================================
Syntax Description
======================================== ================================================
offen Address components include an offset.
======================================== ================================================
.. _amdgpu_synid_addr64:
addr64
~~~~~~
Specifies whether a 64-bit address is used. By default, no address is used.
GFX7 only. Cannot be used with :ref:`offen<amdgpu_synid_offen>` and
:ref:`idxen<amdgpu_synid_idxen>` modifiers.
======================================== ================================================
Syntax Description
======================================== ================================================
addr64 A 64-bit address is used.
======================================== ================================================
.. _amdgpu_synid_buf_offset12:
offset12
~~~~~~~~
Specifies an immediate unsigned 12-bit offset, in bytes. The default value is 0.
================== ====================================================================
Syntax Description
================== ====================================================================
offset:{0..0xFFF} Specifies a 12-bit unsigned offset as a positive
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
================== ====================================================================
Examples:
.. parsed-literal::
offset:x+y
offset:0x10
glc
~~~
See a description :ref:`here<amdgpu_synid_glc>`.
slc
~~~
See a description :ref:`here<amdgpu_synid_slc>`.
lds
~~~
See a description :ref:`here<amdgpu_synid_lds>`.
dlc
~~~
See a description :ref:`here<amdgpu_synid_dlc>`. GFX10 only.
tfe
~~~
See a description :ref:`here<amdgpu_synid_tfe>`.
.. _amdgpu_synid_dfmt:
dfmt
~~~~
TBD
.. _amdgpu_synid_nfmt:
nfmt
~~~~
TBD
SMRD/SMEM Modifiers
-------------------
glc
~~~
See a description :ref:`here<amdgpu_synid_glc>`.
nv
~~
See a description :ref:`here<amdgpu_synid_nv>`. GFX9 only.
dlc
~~~
See a description :ref:`here<amdgpu_synid_dlc>`. GFX10 only.
VINTRP Modifiers
----------------
.. _amdgpu_synid_high:
high
~~~~
Specifies which half of the LDS word to use. Low half of LDS word is used by default.
GFX9 and GFX10 only.
======================================== ================================
Syntax Description
======================================== ================================
high Use high half of LDS word.
======================================== ================================
DPP8 Modifiers
--------------
GFX10 only.
.. _amdgpu_synid_dpp8_sel:
dpp8_sel
~~~~~~~~
Selects which lanes to pull data from, within a group of 8 lanes. This is a mandatory modifier.
There is no default value.
GFX10 only.
The *dpp8_sel* modifier must specify exactly 8 values.
First value selects which lane to read from to supply data into lane 0.
Second value controls lane 1 and so on.
Each value may be specified as either
an :ref:`integer number<amdgpu_synid_integer_number>` or
an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
=============================================================== ===========================
Syntax Description
=============================================================== ===========================
dpp8:[{0..7},{0..7},{0..7},{0..7},{0..7},{0..7},{0..7},{0..7}] Select lanes to read from.
=============================================================== ===========================
Examples:
.. parsed-literal::
dpp8:[7,6,5,4,3,2,1,0]
dpp8:[0,1,0,1,0,1,0,1]
.. _amdgpu_synid_fi8:
fi
~~
Controls interaction with inactive lanes for *dpp8* instructions. The default value is zero.
Note: *inactive* lanes are those whose :ref:`exec<amdgpu_synid_exec>` mask bit is zero.
GFX10 only.
==================================== =====================================================
Syntax Description
==================================== =====================================================
fi:0 Fetch zero when accessing data from inactive lanes.
fi:1 Fetch pre-exist values from inactive lanes.
==================================== =====================================================
Note: numeric values may be specified as either :ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
DPP/DPP16 Modifiers
-------------------
GFX8, GFX9 and GFX10 only.
.. _amdgpu_synid_dpp_ctrl:
dpp_ctrl
~~~~~~~~
Specifies how data are shared between threads. This is a mandatory modifier.
There is no default value.
GFX8 and GFX9 only. Use :ref:`dpp16_ctrl<amdgpu_synid_dpp16_ctrl>` for GFX10.
Note: the lanes of a wavefront are organized in four *rows* and four *banks*.
======================================== ================================================
Syntax Description
======================================== ================================================
quad_perm:[{0..3},{0..3},{0..3},{0..3}] Full permute of 4 threads.
row_mirror Mirror threads within row.
row_half_mirror Mirror threads within 1/2 row (8 threads).
row_bcast:15 Broadcast 15th thread of each row to next row.
row_bcast:31 Broadcast thread 31 to rows 2 and 3.
wave_shl:1 Wavefront left shift by 1 thread.
wave_rol:1 Wavefront left rotate by 1 thread.
wave_shr:1 Wavefront right shift by 1 thread.
wave_ror:1 Wavefront right rotate by 1 thread.
row_shl:{1..15} Row shift left by 1-15 threads.
row_shr:{1..15} Row shift right by 1-15 threads.
row_ror:{1..15} Row rotate right by 1-15 threads.
======================================== ================================================
Note: numeric values may be specified as either
:ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
quad_perm:[0, 1, 2, 3]
row_shl:3
.. _amdgpu_synid_dpp16_ctrl:
dpp16_ctrl
~~~~~~~~~~
Specifies how data are shared between threads. This is a mandatory modifier.
There is no default value.
GFX10 only. Use :ref:`dpp_ctrl<amdgpu_synid_dpp_ctrl>` for GFX8 and GFX9.
Note: the lanes of a wavefront are organized in four *rows* and four *banks*.
(There are only two rows in *wave32* mode.)
======================================== ====================================================
Syntax Description
======================================== ====================================================
quad_perm:[{0..3},{0..3},{0..3},{0..3}] Full permute of 4 threads.
row_mirror Mirror threads within row.
row_half_mirror Mirror threads within 1/2 row (8 threads).
row_share:{0..15} Share the value from the specified lane with other
lanes in the row.
row_xmask:{0..15} Fetch from XOR(current lane id, specified lane id).
row_shl:{1..15} Row shift left by 1-15 threads.
row_shr:{1..15} Row shift right by 1-15 threads.
row_ror:{1..15} Row rotate right by 1-15 threads.
======================================== ====================================================
Note: numeric values may be specified as either
:ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
quad_perm:[0, 1, 2, 3]
row_shl:3
.. _amdgpu_synid_row_mask:
row_mask
~~~~~~~~
Controls which rows are enabled for data sharing. By default, all rows are enabled.
Note: the lanes of a wavefront are organized in four *rows* and four *banks*.
(There are only two rows in *wave32* mode.)
================= ====================================================================
Syntax Description
================= ====================================================================
row_mask:{0..15} Specifies a *row mask* as a positive
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
Each of 4 bits in the mask controls one row
(0 - disabled, 1 - enabled).
In *wave32* mode the values should be limited to 0..7.
================= ====================================================================
Examples:
.. parsed-literal::
row_mask:0xf
row_mask:0b1010
row_mask:x|y
.. _amdgpu_synid_bank_mask:
bank_mask
~~~~~~~~~
Controls which banks are enabled for data sharing. By default, all banks are enabled.
Note: the lanes of a wavefront are organized in four *rows* and four *banks*.
(There are only two rows in *wave32* mode.)
================== ====================================================================
Syntax Description
================== ====================================================================
bank_mask:{0..15} Specifies a *bank mask* as a positive
:ref:`integer number <amdgpu_synid_integer_number>`
or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.
Each of 4 bits in the mask controls one bank
(0 - disabled, 1 - enabled).
================== ====================================================================
Examples:
.. parsed-literal::
bank_mask:0x3
bank_mask:0b0011
bank_mask:x&y
.. _amdgpu_synid_bound_ctrl:
bound_ctrl
~~~~~~~~~~
Controls data sharing when accessing an invalid lane. By default, data sharing with
invalid lanes is disabled.
======================================== ================================================
Syntax Description
======================================== ================================================
bound_ctrl:0 Enables data sharing with invalid lanes.
Accessing data from an invalid lane will
return zero.
======================================== ================================================
.. _amdgpu_synid_fi16:
fi
~~
Controls interaction with *inactive* lanes for *dpp16* instructions. The default value is zero.
Note: *inactive* lanes are those whose :ref:`exec<amdgpu_synid_exec>` mask bit is zero.
GFX10 only.
======================================== ==================================================
Syntax Description
======================================== ==================================================
fi:0 Interaction with inactive lanes is controlled by
:ref:`bound_ctrl<amdgpu_synid_bound_ctrl>`.
fi:1 Fetch pre-exist values from inactive lanes.
======================================== ==================================================
Note: numeric values may be specified as either :ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
SDWA Modifiers
--------------
GFX8, GFX9 and GFX10 only.
clamp
~~~~~
See a description :ref:`here<amdgpu_synid_clamp>`.
omod
~~~~
See a description :ref:`here<amdgpu_synid_omod>`.
GFX9 and GFX10 only.
.. _amdgpu_synid_dst_sel:
dst_sel
~~~~~~~
Selects which bits in the destination are affected. By default, all bits are affected.
======================================== ================================================
Syntax Description
======================================== ================================================
dst_sel:DWORD Use bits 31:0.
dst_sel:BYTE_0 Use bits 7:0.
dst_sel:BYTE_1 Use bits 15:8.
dst_sel:BYTE_2 Use bits 23:16.
dst_sel:BYTE_3 Use bits 31:24.
dst_sel:WORD_0 Use bits 15:0.
dst_sel:WORD_1 Use bits 31:16.
======================================== ================================================
.. _amdgpu_synid_dst_unused:
dst_unused
~~~~~~~~~~
Controls what to do with the bits in the destination which are not selected
by :ref:`dst_sel<amdgpu_synid_dst_sel>`.
By default, unused bits are preserved.
======================================== ================================================
Syntax Description
======================================== ================================================
dst_unused:UNUSED_PAD Pad with zeros.
dst_unused:UNUSED_SEXT Sign-extend upper bits, zero lower bits.
dst_unused:UNUSED_PRESERVE Preserve bits.
======================================== ================================================
.. _amdgpu_synid_src0_sel:
src0_sel
~~~~~~~~
Controls which bits in the src0 are used. By default, all bits are used.
======================================== ================================================
Syntax Description
======================================== ================================================
src0_sel:DWORD Use bits 31:0.
src0_sel:BYTE_0 Use bits 7:0.
src0_sel:BYTE_1 Use bits 15:8.
src0_sel:BYTE_2 Use bits 23:16.
src0_sel:BYTE_3 Use bits 31:24.
src0_sel:WORD_0 Use bits 15:0.
src0_sel:WORD_1 Use bits 31:16.
======================================== ================================================
.. _amdgpu_synid_src1_sel:
src1_sel
~~~~~~~~
Controls which bits in the src1 are used. By default, all bits are used.
======================================== ================================================
Syntax Description
======================================== ================================================
src1_sel:DWORD Use bits 31:0.
src1_sel:BYTE_0 Use bits 7:0.
src1_sel:BYTE_1 Use bits 15:8.
src1_sel:BYTE_2 Use bits 23:16.
src1_sel:BYTE_3 Use bits 31:24.
src1_sel:WORD_0 Use bits 15:0.
src1_sel:WORD_1 Use bits 31:16.
======================================== ================================================
.. _amdgpu_synid_sdwa_operand_modifiers:
SDWA Operand Modifiers
----------------------
Operand modifiers are not used separately. They are applied to source operands.
GFX8, GFX9 and GFX10 only.
abs
~~~
See a description :ref:`here<amdgpu_synid_abs>`.
neg
~~~
See a description :ref:`here<amdgpu_synid_neg>`.
.. _amdgpu_synid_sext:
sext
~~~~
Sign-extends value of a (sub-dword) operand to fill all 32 bits.
Has no effect for 32-bit operands.
Valid for integer operands only.
======================================== ================================================
Syntax Description
======================================== ================================================
sext(<operand>) Sign-extend operand value.
======================================== ================================================
Examples:
.. parsed-literal::
sext(v4)
sext(v255)
VOP3 Modifiers
--------------
.. _amdgpu_synid_vop3_op_sel:
op_sel
~~~~~~
Selects the low [15:0] or high [31:16] operand bits for source and destination operands.
By default, low bits are used for all operands.
The number of values specified with the op_sel modifier must match the number of instruction
operands (both source and destination). First value controls src0, second value controls src1
and so on, except that the last value controls destination.
The value 0 selects the low bits, while 1 selects the high bits.
Note: op_sel modifier affects 16-bit operands only. For 32-bit operands the value specified
by op_sel must be 0.
GFX9 and GFX10 only.
======================================== ============================================================
Syntax Description
======================================== ============================================================
op_sel:[{0..1},{0..1}] Select operand bits for instructions with 1 source operand.
op_sel:[{0..1},{0..1},{0..1}] Select operand bits for instructions with 2 source operands.
op_sel:[{0..1},{0..1},{0..1},{0..1}] Select operand bits for instructions with 3 source operands.
======================================== ============================================================
Note: numeric values may be specified as either
:ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
op_sel:[0,0]
op_sel:[0,1]
.. _amdgpu_synid_clamp:
clamp
~~~~~
Clamp meaning depends on instruction.
For *v_cmp* instructions, clamp modifier indicates that the compare signals
if a floating point exception occurs. By default, signaling is disabled.
Not supported by GFX7.
For integer operations, clamp modifier indicates that the result must be clamped
to the largest and smallest representable value. By default, there is no clamping.
Integer clamping is not supported by GFX7.
For floating point operations, clamp modifier indicates that the result must be clamped
to the range [0.0, 1.0]. By default, there is no clamping.
Note: clamp modifier is applied after :ref:`output modifiers<amdgpu_synid_omod>` (if any).
======================================== ================================================
Syntax Description
======================================== ================================================
clamp Enables clamping (or signaling).
======================================== ================================================
.. _amdgpu_synid_omod:
omod
~~~~
Specifies if an output modifier must be applied to the result.
By default, no output modifiers are applied.
Note: output modifiers are applied before :ref:`clamping<amdgpu_synid_clamp>` (if any).
Output modifiers are valid for f32 and f64 floating point results only.
They must not be used with f16.
Note: *v_cvt_f16_f32* is an exception. This instruction produces f16 result
but accepts output modifiers.
======================================== ================================================
Syntax Description
======================================== ================================================
mul:2 Multiply the result by 2.
mul:4 Multiply the result by 4.
div:2 Multiply the result by 0.5.
======================================== ================================================
Note: numeric values may be specified as either :ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
mul:2
mul:x // x must be equal to 2 or 4
.. _amdgpu_synid_vop3_operand_modifiers:
VOP3 Operand Modifiers
----------------------
Operand modifiers are not used separately. They are applied to source operands.
.. _amdgpu_synid_abs:
abs
~~~
Computes the absolute value of its operand. Must be applied before :ref:`neg<amdgpu_synid_neg>`
(if any). Valid for floating point operands only.
======================================== ====================================================
Syntax Description
======================================== ====================================================
abs(<operand>) Get the absolute value of a floating-point operand.
\|<operand>| The same as above (an SP3 syntax).
======================================== ====================================================
Note: avoid using SP3 syntax with operands specified as expressions because the trailing '|'
may be misinterpreted. Such operands should be enclosed into additional parentheses as shown
in examples below.
Examples:
.. parsed-literal::
abs(v36)
\|v36|
abs(x|y) // ok
\|(x|y)| // additional parentheses are required
.. _amdgpu_synid_neg:
neg
~~~
Computes the negative value of its operand. Must be applied after :ref:`abs<amdgpu_synid_abs>`
(if any). Valid for floating point operands only.
================== ====================================================
Syntax Description
================== ====================================================
neg(<operand>) Get the negative value of a floating-point operand.
The operand may include an optional
:ref:`abs<amdgpu_synid_abs>` modifier.
-<operand> The same as above (an SP3 syntax).
================== ====================================================
Note: SP3 syntax is supported with limitations because of a potential ambiguity.
Currently it is allowed in the following cases:
* Before a register.
* Before an :ref:`abs<amdgpu_synid_abs>` modifier.
* Before an SP3 :ref:`abs<amdgpu_synid_abs>` modifier.
In all other cases "-" is handled as a part of an expression that follows the sign.
Examples:
.. parsed-literal::
// Operands with negate modifiers
neg(v[0])
neg(1.0)
neg(abs(v0))
-v5
-abs(v5)
-\|v5|
// Operands without negate modifiers
-1
-x+y
VOP3P Modifiers
---------------
This section describes modifiers of *regular* VOP3P instructions.
*v_mad_mix_f32*, *v_mad_mixhi_f16* and *v_mad_mixlo_f16*
instructions use these modifiers :ref:`in a special manner<amdgpu_synid_mad_mix>`.
GFX9 and GFX10 only.
.. _amdgpu_synid_op_sel:
op_sel
~~~~~~
Selects the low [15:0] or high [31:16] operand bits as input to the operation
which results in the lower-half of the destination.
By default, low bits are used for all operands.
The number of values specified by the *op_sel* modifier must match the number of source
operands. First value controls src0, second value controls src1 and so on.
The value 0 selects the low bits, while 1 selects the high bits.
================================= =============================================================
Syntax Description
================================= =============================================================
op_sel:[{0..1}] Select operand bits for instructions with 1 source operand.
op_sel:[{0..1},{0..1}] Select operand bits for instructions with 2 source operands.
op_sel:[{0..1},{0..1},{0..1}] Select operand bits for instructions with 3 source operands.
================================= =============================================================
Note: numeric values may be specified as either
:ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
op_sel:[0,0]
op_sel:[0,1,0]
.. _amdgpu_synid_op_sel_hi:
op_sel_hi
~~~~~~~~~
Selects the low [15:0] or high [31:16] operand bits as input to the operation
which results in the upper-half of the destination.
By default, high bits are used for all operands.
The number of values specified by the *op_sel_hi* modifier must match the number of source
operands. First value controls src0, second value controls src1 and so on.
The value 0 selects the low bits, while 1 selects the high bits.
=================================== =============================================================
Syntax Description
=================================== =============================================================
op_sel_hi:[{0..1}] Select operand bits for instructions with 1 source operand.
op_sel_hi:[{0..1},{0..1}] Select operand bits for instructions with 2 source operands.
op_sel_hi:[{0..1},{0..1},{0..1}] Select operand bits for instructions with 3 source operands.
=================================== =============================================================
Note: numeric values may be specified as either
:ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
op_sel_hi:[0,0]
op_sel_hi:[0,0,1]
.. _amdgpu_synid_neg_lo:
neg_lo
~~~~~~
Specifies whether to change sign of operand values selected by
:ref:`op_sel<amdgpu_synid_op_sel>`. These values are then used
as input to the operation which results in the upper-half of the destination.
The number of values specified by this modifier must match the number of source
operands. First value controls src0, second value controls src1 and so on.
The value 0 indicates that the corresponding operand value is used unmodified,
the value 1 indicates that negative value of the operand must be used.
By default, operand values are used unmodified.
This modifier is valid for floating point operands only.
================================ ==================================================================
Syntax Description
================================ ==================================================================
neg_lo:[{0..1}] Select affected operands for instructions with 1 source operand.
neg_lo:[{0..1},{0..1}] Select affected operands for instructions with 2 source operands.
neg_lo:[{0..1},{0..1},{0..1}] Select affected operands for instructions with 3 source operands.
================================ ==================================================================
Note: numeric values may be specified as either
:ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
neg_lo:[0]
neg_lo:[0,1]
.. _amdgpu_synid_neg_hi:
neg_hi
~~~~~~
Specifies whether to change sign of operand values selected by
:ref:`op_sel_hi<amdgpu_synid_op_sel_hi>`. These values are then used
as input to the operation which results in the upper-half of the destination.
The number of values specified by this modifier must match the number of source
operands. First value controls src0, second value controls src1 and so on.
The value 0 indicates that the corresponding operand value is used unmodified,
the value 1 indicates that negative value of the operand must be used.
By default, operand values are used unmodified.
This modifier is valid for floating point operands only.
=============================== ==================================================================
Syntax Description
=============================== ==================================================================
neg_hi:[{0..1}] Select affected operands for instructions with 1 source operand.
neg_hi:[{0..1},{0..1}] Select affected operands for instructions with 2 source operands.
neg_hi:[{0..1},{0..1},{0..1}] Select affected operands for instructions with 3 source operands.
=============================== ==================================================================
Note: numeric values may be specified as either
:ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
neg_hi:[1,0]
neg_hi:[0,1,1]
clamp
~~~~~
See a description :ref:`here<amdgpu_synid_clamp>`.
.. _amdgpu_synid_mad_mix:
VOP3P V_MAD_MIX Modifiers
-------------------------
*v_mad_mix_f32*, *v_mad_mixhi_f16* and *v_mad_mixlo_f16* instructions
use *op_sel* and *op_sel_hi* modifiers
in a manner different from *regular* VOP3P instructions.
See a description below.
GFX9 and GFX10 only.
.. _amdgpu_synid_mad_mix_op_sel:
m_op_sel
~~~~~~~~
This operand has meaning only for 16-bit source operands as indicated by
:ref:`m_op_sel_hi<amdgpu_synid_mad_mix_op_sel_hi>`.
It specifies to select either the low [15:0] or high [31:16] operand bits
as input to the operation.
The number of values specified by the *op_sel* modifier must match the number of source
operands. First value controls src0, second value controls src1 and so on.
The value 0 indicates the low bits, the value 1 indicates the high 16 bits.
By default, low bits are used for all operands.
=============================== ================================================
Syntax Description
=============================== ================================================
op_sel:[{0..1},{0..1},{0..1}] Select location of each 16-bit source operand.
=============================== ================================================
Note: numeric values may be specified as either
:ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
op_sel:[0,1]
.. _amdgpu_synid_mad_mix_op_sel_hi:
m_op_sel_hi
~~~~~~~~~~~
Selects the size of source operands: either 32 bits or 16 bits.
By default, 32 bits are used for all source operands.
The number of values specified by the *op_sel_hi* modifier must match the number of source
operands. First value controls src0, second value controls src1 and so on.
The value 0 indicates 32 bits, the value 1 indicates 16 bits.
The location of 16 bits in the operand may be specified by
:ref:`m_op_sel<amdgpu_synid_mad_mix_op_sel>`.
======================================== ====================================
Syntax Description
======================================== ====================================
op_sel_hi:[{0..1},{0..1},{0..1}] Select size of each source operand.
======================================== ====================================
Note: numeric values may be specified as either
:ref:`integer numbers<amdgpu_synid_integer_number>` or
:ref:`absolute expressions<amdgpu_synid_absolute_expression>`.
Examples:
.. parsed-literal::
op_sel_hi:[1,1,1]
abs
~~~
See a description :ref:`here<amdgpu_synid_abs>`.
neg
~~~
See a description :ref:`here<amdgpu_synid_neg>`.
clamp
~~~~~
See a description :ref:`here<amdgpu_synid_clamp>`.
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