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AMDGPU: Improve documentation.
Summary: Add links to ISA manuals and ABI. Add text about assembler syntax. Add info about instructions operands. Add instruction examples for each encoding. Update directives section, add missing .amdgpu_hsa_kernel. Reviewers: tstellarAMD, SamWot, vpykhtin Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, tony-tye, artem.tamazov, llvm-commits Differential Revision: https://reviews.llvm.org/D24724 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281962 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nikolay Haustov
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2a3c739021
@ -8,6 +8,8 @@ Introduction
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The AMDGPU back-end provides ISA code generation for AMD GPUs, starting with
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the R600 family up until the current Volcanic Islands (GCN Gen 3).
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Refer to `AMDGPU section in Architecture & Platform Information for Compiler Writers <CompilerWriterInfo.html#amdgpu>`_
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for additional documentation.
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Conventions
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===========
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@ -35,96 +37,241 @@ OpenCL standard.
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Assembler
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=========
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The assembler is currently considered experimental.
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AMDGPU backend has LLVM-MC based assembler which is currently in development.
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It supports Southern Islands ISA, Sea Islands and Volcanic Islands.
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For syntax examples look in test/MC/AMDGPU.
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This document describes general syntax for instructions and operands. For more
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information about instructions, their semantics and supported combinations
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of operands, refer to one of Instruction Set Architecture manuals.
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Below some of the currently supported features (modulo bugs). These
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all apply to the Southern Islands ISA, Sea Islands and Volcanic Islands
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are also supported but may be missing some instructions and have more bugs:
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An instruction has the following syntax (register operands are
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normally comma-separated while extra operands are space-separated):
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DS Instructions
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---------------
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All DS instructions are supported.
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*<opcode> <register_operand0>, ... <extra_operand0> ...*
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FLAT Instructions
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------------------
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These instructions are only present in the Sea Islands and Volcanic Islands
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instruction set. All FLAT instructions are supported for these architectures
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MUBUF Instructions
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------------------
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All non-atomic MUBUF instructions are supported.
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Operands
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--------
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SMRD Instructions
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-----------------
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Only the s_load_dword* SMRD instructions are supported.
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The following syntax for register operands is supported:
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SOP1 Instructions
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-----------------
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All SOP1 instructions are supported.
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* SGPR registers: s0, ... or s[0], ...
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* VGPR registers: v0, ... or v[0], ...
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* TTMP registers: ttmp0, ... or ttmp[0], ...
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* Special registers: exec (exec_lo, exec_hi), vcc (vcc_lo, vcc_hi), flat_scratch (flat_scratch_lo, flat_scratch_hi)
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* Special trap registers: tba (tba_lo, tba_hi), tma (tma_lo, tma_hi)
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* Register pairs, quads, etc: s[2:3], v[10:11], ttmp[5:6], s[4:7], v[12:15], ttmp[4:7], s[8:15], ...
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* Register lists: [s0, s1], [ttmp0, ttmp1, ttmp2, ttmp3]
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* Register index expressions: v[2*2], s[1-1:2-1]
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* 'off' indicates that an operand is not enabled
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SOP2 Instructions
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-----------------
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All SOP2 instructions are supported.
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The following extra operands are supported:
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SOPC Instructions
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-----------------
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All SOPC instructions are supported.
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* offset, offset0, offset1
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* idxen, offen bits
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* glc, slc, tfe bits
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* waitcnt: integer or combination of counter values
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* VOP3 modifiers:
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SOPP Instructions
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-----------------
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- abs (\| \|), neg (\-)
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Unless otherwise mentioned, all SOPP instructions that have one or more
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operands accept integer operands only. No verification is performed
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on the operands, so it is up to the programmer to be familiar with the
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* DPP modifiers:
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- row_shl, row_shr, row_ror, row_rol
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- row_mirror, row_half_mirror, row_bcast
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- wave_shl, wave_shr, wave_ror, wave_rol, quad_perm
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- row_mask, bank_mask, bound_ctrl
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* SDWA modifiers:
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- dst_sel, src0_sel, src1_sel (BYTE_N, WORD_M, DWORD)
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- dst_unused (UNUSED_PAD, UNUSED_SEXT, UNUSED_PRESERVE)
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- abs, neg, sext
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DS Instructions Examples
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------------------------
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.. code-block:: nasm
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ds_add_u32 v2, v4 offset:16
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ds_write_src2_b64 v2 offset0:4 offset1:8
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ds_cmpst_f32 v2, v4, v6
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ds_min_rtn_f64 v[8:9], v2, v[4:5]
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For full list of supported instructions, refer to "LDS/GDS instructions" in ISA Manual.
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FLAT Instruction Examples
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--------------------------
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.. code-block:: nasm
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flat_load_dword v1, v[3:4]
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flat_store_dwordx3 v[3:4], v[5:7]
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flat_atomic_swap v1, v[3:4], v5 glc
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flat_atomic_cmpswap v1, v[3:4], v[5:6] glc slc
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flat_atomic_fmax_x2 v[1:2], v[3:4], v[5:6] glc
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For full list of supported instructions, refer to "FLAT instructions" in ISA Manual.
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MUBUF Instruction Examples
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---------------------------
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.. code-block:: nasm
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buffer_load_dword v1, off, s[4:7], s1
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buffer_store_dwordx4 v[1:4], v2, ttmp[4:7], s1 offen offset:4 glc tfe
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buffer_store_format_xy v[1:2], off, s[4:7], s1
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buffer_wbinvl1
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buffer_atomic_inc v1, v2, s[8:11], s4 idxen offset:4 slc
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For full list of supported instructions, refer to "MUBUF Instructions" in ISA Manual.
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SMRD/SMEM Instruction Examples
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-------------------------------
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.. code-block:: nasm
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s_load_dword s1, s[2:3], 0xfc
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s_load_dwordx8 s[8:15], s[2:3], s4
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s_load_dwordx16 s[88:103], s[2:3], s4
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s_dcache_inv_vol
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s_memtime s[4:5]
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For full list of supported instructions, refer to "Scalar Memory Operations" in ISA Manual.
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SOP1 Instruction Examples
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--------------------------
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.. code-block:: nasm
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s_mov_b32 s1, s2
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s_mov_b64 s[0:1], 0x80000000
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s_cmov_b32 s1, 200
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s_wqm_b64 s[2:3], s[4:5]
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s_bcnt0_i32_b64 s1, s[2:3]
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s_swappc_b64 s[2:3], s[4:5]
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s_cbranch_join s[4:5]
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For full list of supported instructions, refer to "SOP1 Instructions" in ISA Manual.
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SOP2 Instruction Examples
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-------------------------
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.. code-block:: nasm
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s_add_u32 s1, s2, s3
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s_and_b64 s[2:3], s[4:5], s[6:7]
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s_cselect_b32 s1, s2, s3
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s_andn2_b32 s2, s4, s6
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s_lshr_b64 s[2:3], s[4:5], s6
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s_ashr_i32 s2, s4, s6
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s_bfm_b64 s[2:3], s4, s6
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s_bfe_i64 s[2:3], s[4:5], s6
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s_cbranch_g_fork s[4:5], s[6:7]
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For full list of supported instructions, refer to "SOP2 Instructions" in ISA Manual.
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SOPC Instruction Examples
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--------------------------
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.. code-block:: nasm
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s_cmp_eq_i32 s1, s2
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s_bitcmp1_b32 s1, s2
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s_bitcmp0_b64 s[2:3], s4
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s_setvskip s3, s5
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For full list of supported instructions, refer to "SOPC Instructions" in ISA Manual.
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SOPP Instruction Examples
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--------------------------
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.. code-block:: nasm
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s_barrier
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s_nop 2
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s_endpgm
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s_waitcnt 0 ; Wait for all counters to be 0
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s_waitcnt vmcnt(0) & expcnt(0) & lgkmcnt(0) ; Equivalent to above
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s_waitcnt vmcnt(1) ; Wait for vmcnt counter to be 1.
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s_sethalt 9
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s_sleep 10
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s_sendmsg 0x1
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s_sendmsg sendmsg(MSG_INTERRUPT)
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s_trap 1
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For full list of supported instructions, refer to "SOPP Instructions" in ISA Manual.
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Unless otherwise mentioned, little verification is performed on the operands
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of SOPP Instrucitons, so it is up to the programmer to be familiar with the
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range or acceptable values.
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s_waitcnt
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^^^^^^^^^
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Vector ALU Instruction Examples
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-------------------------------
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s_waitcnt accepts named arguments to specify which memory counter(s) to
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wait for.
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For vector ALU instruction opcodes (VOP1, VOP2, VOP3, VOPC, VOP_DPP, VOP_SDWA),
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the assembler will automatically use optimal encoding based on its operands.
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To force specific encoding, one can add a suffix to the opcode of the instruction:
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* _e32 for 32-bit VOP1/VOP2/VOPC
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* _e64 for 64-bit VOP3
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* _dpp for VOP_DPP
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* _sdwa for VOP_SDWA
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VOP1/VOP2/VOP3/VOPC examples:
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.. code-block:: nasm
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; Wait for all counters to be 0
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s_waitcnt 0
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v_mov_b32 v1, v2
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v_mov_b32_e32 v1, v2
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v_nop
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v_cvt_f64_i32_e32 v[1:2], v2
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v_floor_f32_e32 v1, v2
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v_bfrev_b32_e32 v1, v2
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v_add_f32_e32 v1, v2, v3
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v_mul_i32_i24_e64 v1, v2, 3
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v_mul_i32_i24_e32 v1, -3, v3
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v_mul_i32_i24_e32 v1, -100, v3
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v_addc_u32 v1, s[0:1], v2, v3, s[2:3]
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v_max_f16_e32 v1, v2, v3
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; Equivalent to s_waitcnt 0. Counter names can also be delimited by
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; '&' or ','.
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s_waitcnt vmcnt(0) expcnt(0) lgkcmt(0)
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; Wait for vmcnt counter to be 1.
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s_waitcnt vmcnt(1)
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VOP1, VOP2, VOP3, VOPC Instructions
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-----------------------------------
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All 32-bit and 64-bit encodings should work.
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The assembler will automatically detect which encoding size to use for
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VOP1, VOP2, and VOPC instructions based on the operands. If you want to force
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a specific encoding size, you can add an _e32 (for 32-bit encoding) or
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_e64 (for 64-bit encoding) suffix to the instruction. Most, but not all
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instructions support an explicit suffix. These are all valid assembly
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strings:
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VOP_DPP examples:
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.. code-block:: nasm
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v_mul_i32_i24 v1, v2, v3
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v_mul_i32_i24_e32 v1, v2, v3
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v_mul_i32_i24_e64 v1, v2, v3
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v_mov_b32 v0, v0 quad_perm:[0,2,1,1]
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v_sin_f32 v0, v0 row_shl:1 row_mask:0xa bank_mask:0x1 bound_ctrl:0
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v_mov_b32 v0, v0 wave_shl:1
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v_mov_b32 v0, v0 row_mirror
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v_mov_b32 v0, v0 row_bcast:31
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v_mov_b32 v0, v0 quad_perm:[1,3,0,1] row_mask:0xa bank_mask:0x1 bound_ctrl:0
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v_add_f32 v0, v0, |v0| row_shl:1 row_mask:0xa bank_mask:0x1 bound_ctrl:0
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v_max_f16 v1, v2, v3 row_shl:1 row_mask:0xa bank_mask:0x1 bound_ctrl:0
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Assembler Directives
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--------------------
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VOP_SDWA examples:
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.. code-block:: nasm
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v_mov_b32 v1, v2 dst_sel:BYTE_0 dst_unused:UNUSED_PRESERVE src0_sel:DWORD
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v_min_u32 v200, v200, v1 dst_sel:WORD_1 dst_unused:UNUSED_PAD src0_sel:BYTE_1 src1_sel:DWORD
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v_sin_f32 v0, v0 dst_unused:UNUSED_PAD src0_sel:WORD_1
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v_fract_f32 v0, |v0| dst_sel:DWORD dst_unused:UNUSED_PAD src0_sel:WORD_1
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v_cmpx_le_u32 vcc, v1, v2 src0_sel:BYTE_2 src1_sel:WORD_0
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For full list of supported instructions, refer to "Vector ALU instructions".
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HSA Code Object Directives
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--------------------------
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AMDGPU ABI defines auxiliary data in output code object. In assembly source,
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one can specify them with assembler directives.
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.hsa_code_object_version major, minor
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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*major* and *minor* are integers that specify the version of the HSA code
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object that will be generated by the assembler. This value will be stored
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in an entry of the .note section.
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object that will be generated by the assembler.
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.hsa_code_object_isa [major, minor, stepping, vendor, arch]
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -135,12 +282,14 @@ set architecture (ISA) version of the assembly program.
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*vendor* and *arch* are quoted strings. *vendor* should always be equal to
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"AMD" and *arch* should always be equal to "AMDGPU".
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If no arguments are specified, then the assembler will derive the ISA version,
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*vendor*, and *arch* from the value of the -mcpu option that is passed to the
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assembler.
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By default, the assembler will derive the ISA version, *vendor*, and *arch*
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from the value of the -mcpu option that is passed to the assembler.
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ISA version, *vendor*, and *arch* will all be stored in a single entry of the
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.note section.
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.amdgpu_hsa_kernel (name)
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^^^^^^^^^^^^^^^^^^^^^^^^^
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This directives specifies that the symbol with given name is a kernel entry point
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(label) and the object should contain corresponding symbol of type STT_AMDGPU_HSA_KERNEL.
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.amd_kernel_code_t
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^^^^^^^^^^^^^^^^^^
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@ -165,9 +314,8 @@ used. The default value for all keys is 0, with the following exceptions:
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The *.amd_kernel_code_t* directive must be placed immediately after the
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function label and before any instructions.
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For a full list of amd_kernel_code_t keys, see the examples in
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test/CodeGen/AMDGPU/hsa.s. For an explanation of the meanings of the different
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keys, see the comments in lib/Target/AMDGPU/AmdKernelCodeT.h
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For a full list of amd_kernel_code_t keys, refer to AMDGPU ABI document,
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comments in lib/Target/AMDGPU/AmdKernelCodeT.h and test/CodeGen/AMDGPU/hsa.s.
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Here is an example of a minimal amd_kernel_code_t specification:
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@ -78,8 +78,10 @@ AMDGPU
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* `AMD Cayman/Trinity shader ISA <http://developer.amd.com/wordpress/media/2012/10/AMD_HD_6900_Series_Instruction_Set_Architecture.pdf>`_
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* `AMD Southern Islands Series ISA <http://developer.amd.com/wordpress/media/2012/12/AMD_Southern_Islands_Instruction_Set_Architecture.pdf>`_
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* `AMD Sea Islands Series ISA <http://developer.amd.com/wordpress/media/2013/07/AMD_Sea_Islands_Instruction_Set_Architecture.pdf>`_
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* `AMD GCN3 Instruction Set Architecture <http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/12/AMD_GCN3_Instruction_Set_Architecture_rev1.1.pdf>`__
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* `AMD GPU Programming Guide <http://developer.amd.com/download/AMD_Accelerated_Parallel_Processing_OpenCL_Programming_Guide.pdf>`_
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* `AMD Compute Resources <http://developer.amd.com/tools/heterogeneous-computing/amd-accelerated-parallel-processing-app-sdk/documentation/>`_
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* `AMDGPU Compute Application Binary Interface <https://github.com/RadeonOpenCompute/ROCm-ComputeABI-Doc/blob/master/AMDGPU-ABI.md>`__
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SPARC
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-----
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