wiki:GcnInstrsSop2

Version 1 (modified by trac, 5 years ago) (diff)

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GCN ISA SOP2 instructions

Encoding

The basic encoding of the SOP2 instructions needs 4 bytes (dword). List of fields:

Bits Name Description
0-7 SSRC0 First scalar source operand. Refer to operand encoding
8-15 SSRC1 Second scalar source operand. Refer to operand encoding
16-22 SDST Destination scalar operand. Refer to operand encoding
23-29 OPCODE Operation code
30-31 ENCODING Encoding type. Must be 0b10

Syntax for all instructions: INSTRUCTION SDST, SSRC0, SSRC1

Example: s_and_b32 s0, s1, s2

List of the instruction by opcode:

Opcode Mnemonic
0 S_ADD_U32
1 S_SUB_U32
2 S_ADD_I32
3 S_SUB_I32
4 S_ADDC_U32
5 S_SUBB_U32
6 S_MIN_I32
7 S_MIN_U32

Instruction set

Alphabetically sorted instruction list:

S_ADDC_U32

Opcode: 4 (0x4)
Syntax: S_ADDC_U32 SDST, SSRC0, SSRC1
Descrition: Add SSRC0 to SSRC1 with SCC value and store result into SDST and store carry-out flag into SCC.
Operation:
temp = (UINT64)SSRC0 + (UINT64)SSRC1 + SCC SDST = temp SCC = temp>>32

S_ADD_I32

Opcode: 2 (0x2)
Syntax: S_ADD_I32 SDST, SSRC0, SSRC1
Description: Add SSRC0 to SSRC1 and store result into SDST and store overflow flag into SCC.
Operation:

SDST = SSRC0 + SSRC1 temp = (UINT64)SSRC0 + (UINT64)SSRC1 SCC = temp>((1LL<<31)-1) || temp>(-1LL<<31)

S_ADD_U32

Opcode: 0 (0x0)
Syntax: S_ADD_U32 SDST, SSRC0, SSRC1
Description: Add SSRC0 to SSRC1 and store result into SDST and store carry-out into SCC.
Operation:
SDST = SSRC0 + SSRC1 SCC = ((UINT64)SSRC0 + (UINT64)SSRC1)>>32

S_MIN_I32

Opcode: 6 (0x6) Syntax: S_MIN_I32 SDST, SSRC0, SSRC1
Description: Choose smallest signed value value from SSRC0 and SSRC1 and store its into SDST, and store 1 to SCC if SSSRC0 value has been choosen, otherwise store 0 to SCC
Operation:
SDST = (INT32)SSSRC0<(INT32)SSSRC1 ? SSSRC0 : SSSRC1 SCC = (INT32)SSSRC0<(INT32)SSSRC1

S_MIN_U32

Opcode: 7 (0x7)
Syntax: S_MIN_U32 SDST, SSRC0, SSRC1
Description: Choose smallest unsigned value value from SSRC0 and SSRC1 and store its into SDST, and store 1 to SCC if SSSRC0 value has been choosen, otherwise store 0 to SCC
Operation:
SDST = (UINT32)SSSRC0<(UINT32)SSSRC1 ? SSSRC0 : SSSRC1 SCC = (UINT32)SSSRC0<(UINT32)SSSRC1

S_SUBB_U32

Opcode: 5 (0x5)
Syntax: S_SUBB_U32 SDST, SSRC0, SSRC1
Descrition: Subtract SSRC0 to SSRC1 with SCC value and store result into SDST and store carry-out flag into SCC.
Operation:
temp = (UINT64)SSRC0 - (UINT64)SSRC1 - SCC SDST = temp SCC = temp>>32

S_SUB_I32

Opcode: 3 (0x3)
Syntax: S_SUB_I32 SDST, SSRC0, SSRC1
Description: Subtract SSRC0 to SSRC1 and store result into SDST and store overflow flag into SCC. SCC register value can be BROKEN for some architectures (GCN1.0)
Operation:
SDST = SSRC0 - SSRC1 temp = (UINT64)SSRC0 - (UINT64)SSRC1 SCC = temp>((1LL<<31)-1) || temp>(-1LL<<31)

S_SUB_U32

Opcode: 1 (0x1)
Syntax: S_SUB_U32 SDST, SSRC0, SSRC1
Description: Subtract SSRC0 to SSRC1 and store result into SDST and store borrow into SCC.
Operation:
SDST = SSRC0 - SSRC1 SCC = ((INT64)SSRC0 - (INT64)SSRC1)>>32