SASS Encoding Dispatch & Format Tables

Addresses apply to ptxas v13.0.88 (CUDA 13.0). VA base 0x400000 (non-PIE).

Browsable data dump for the SASS encoder and its function-pointer dispatch tables. Every value here is read directly from the binary's .rodata; the consuming code is documented on the encoder pages.

Encoder Dispatch Layers

The encoder routes one logical instruction through four function-pointer layers plus a scalar opcode→slot table, all drawing handlers from one shared pool. The per-SM array is the authoritative per-architecture override.

Layer	Region VA	Indexing scheme	Keyed by	Distinct handlers	Note
`opcode_to_encoding`	`0x22B4B60`	flat `u16[222]`	opcode index	—	opcode → encoding slot (sentinel 355)
`encoding_tree_1`	`0x233BE00`–`0x2353E00`	16-byte slotted tree (274 internal / 5,169 leaf)	`(format_id<<8)\|minor`	4,618	primary format + handler selection
`encoding_tree_2`	`0x235CE00`–`0x2379E00`	16-byte slotted tree (427 internal / 6,251 leaf)	`(format_id<<8)\|minor`	—	secondary/extended tree (shares pool)
`sass_handler_dispatch_1`	`0x22C0E00`–`0x22F1E00`	`(opcode, category, variant)` sub-tables	opcode id	6,915	superset emit-handler list
`sass_handler_dispatch_2`	`0x2379E00`–`0x2399E00`	`(opcode, category, variant)` sub-tables	opcode id	3,478	strict subset of `_1`
`per_sm_handler_dispatch`	`0x22E7AD0`–`0x23B99D0`	5 × `{u64 op, u64 ptr, u64 pad}` arrays	`(format_id<<8)\|minor`	2,421	per-arch override (sm50_7x / sm75 / sm100 / sm80_8x / sm86_89)
`isel_vtable` (`off_22AD230`, `off_23B3A80`)	`0x22AD230`, `0x23B3A80`	C++ vtables	virtual slot	3,707	ISel node vtables — NOT encoder dispatch
`encoder_handler_union`	—	—	—	8,874	union of tree + sass1 + sass2 + per_sm

Reconciliation matrix (handlers shared between layers)

Layer	encoding_tree	sass_dispatch_1	sass_dispatch_2	per_sm_dispatch	isel_vtable
encoding_tree	4,618	2,828	3,367	2,194	0
sass_dispatch_1	2,828	6,915	2,832	1,711	0
sass_dispatch_2	3,367	2,832	3,478	1,899	0
per_sm_dispatch	2,194	1,711	1,899	2,421	0
isel_vtable	0	0	0	0	3,707

The isel_vtable row/column is zero against every encoder layer: the two C++ vtables share no handler with any genuine encoder dispatch, which is the proof that they are ISel node vtables, not an alternate encoder path.

Encoding-tree geometry (16-byte slots)

Tree	Window	slots in window	internal	leaf	reserved tail
encoding_tree_1	`0x233BE00`–`0x2353E00`	6,144	274	5,169	701
encoding_tree_2	`0x235CE00`–`0x2379E00`	7,424	427	6,251	746
total	—	13,568	701	11,420	1,447

Leaf flavors (across 11,420 leaves): key_handler 4,117 ({dispatch_key, handler}; 396 distinct keys, 2,542 distinct handlers), handler_value 3,635 ({handler, extra}), null_or_data 3,668 (inline data or terminator).

Opcode → encoding slot — sentinel-355 opcodes

opcode_to_encoding (u16[222]) carries 117 non-zero non-sentinel slots, 95 zeros, and 10 sentinel-355 entries. Sentinel 355 means "extended / macro-lowered — no default encoding, requires the ISel resolver's SM-specific vtable override":

Opcode	Mnemonic	Opcode	Mnemonic
40	FCHK	213	CREATEPOLICY
49	FRND	214	CVTA
169	S2UR	215	DMMA
212	CGAERRBAR	216	ELECT
—	—	219	FENCE_S
—	—	220	FMNMX

Format Descriptors (38 entries)

Each format descriptor is a 136-byte .rodata record at 0x23F1D70+. The xmmword header is loaded into the encoding context at a1+8; the trailing slot arrays define operand geometry. format_id is the value emitted at bits[25:31]; width_bits is the instruction word width; slot_sizes/slot_types/slot_flags are the per-slot geometry.

#	VA	Label	format_id	width	slots	slot_sizes	slot_types	slot_flags	encoders
0	`0x23F1D70`	64b_B	4	64	1	8	—	0	70
1	`0x23F1DF8`	128b_0x03	8	128	2	10,17	28	0,3	202
2	`0x23F1E80`	128b_0x09_idx2	9	128	2	8,17	28	0,4	0
3	`0x23F1F08`	64b_A	3	64	1	10	—	0	215
4	`0x23F1F90`	64b_C	2	64	1	8	12	0	20
5	`0x23F2018`	128b_0x07	6	128	2	10,17	24	0,3	26
6	`0x23F20A0`	128b_0x04_idx6	4	128	2	10,17	20	0,3	0
7	`0x23F2128`	128b_0x09	7	128	2	8,17	24	0,4	2
8	`0x23F21B0`	128b_0x0A	10	128	2	10,17	—	0,3	135
9	`0x23F2238`	64b_D	2	64	1	10	14	0	17
10	`0x23F22C0`	128b_0x09_idx10	9	128	2	8,17	28	0,4	0
11	`0x23F2348`	128b_0x0D	8	128	2	10,17	28	0,3	11
12	`0x23F23D0`	128b_0x0B_idx12	11	128	2	8,17	—	0,4	0
13	`0x23F2458`	128b_0x08_idx13	8	128	2	8,17	26	0,4	0
14	`0x23F24E0`	64b_0x03_idx14	3	64	1	6	12	0	0
15	`0x23F2568`	128b_0x08_idx15	8	128	2	12,17	30	0,2	0
16	`0x23F25F0`	128b_0x12	9	128	2	10,17	30	0,3	21
17	`0x23F2678`	128b_0x13	9	128	2	12,17	—	0,2	143
18	`0x23F2700`	128b_0x0B_idx18	11	128	2	6,17	30	0,5	0
19	`0x23F2788`	64b_0x05_idx19	5	64	1	6	—	0	0
20	`0x23F2810`	128b_0x16	7	128	2	10,17	26	0,3	6
21	`0x23F2898`	128b_0x05_idx21	5	128	2	12,17	24	0,2	0
22	`0x23F2920`	128b_0x05_idx22	5	128	2	8,17	20	0,4	0
23	`0x23F29A8`	128b_0x19	7	128	2	12,17	28	0,2	152
24	`0x23F2A30`	128b_0x06_idx24	6	128	2	12,17	26	0,2	0
25	`0x23F2AB8`	128b_0x0D_idx25	13	128	3	12,17,33	42	0,2,9	0
26	`0x23F2B40`	128b_0x0E_idx26	14	128	3	8,17,33	40	0,4,11	0
27	`0x23F2BC8`	128b_0x07_idx27	7	128	2	8,17	24	0,4	0
28	`0x23F2C50`	64b_E	1	64	1	10	12	0	1
29	`0x23F2CD8`	128b_0x10_idx29	16	128	3	8,17,33	44,52,68,84,100,116	0,4,11	0
30	`0x23F2D60`	64b_0x04_idx30	4	64	1	6	14	0	0
31	`0x23F2DE8`	128b_0x21	6	128	2	10,17	24	0,3	2
32	`0x23F2E70`	64b_0x02_idx32	2	64	1	12	—	0	0
33	`0x23F2EF8`	128b_0x23	7	128	2	12,17	28	0,2	9
34	`0x23F2F80`	128b_0x07_idx34	7	128	2	14,17	30	0,1	0
35	`0x23F3008`	128b_0x08_idx35	8	128	2	14,17	—	0,1	0
36	`0x23F3090`	128b_0x0C_idx36	12	128	3	14,17,33	42	0,1,8	0
37	`0x23F3118`	128b_0x0D_idx37	13	128	3	10,17,33	40	0,3,10	0

Universal slot template (0x23F1C60, refcount 7,302 — the most-shared slot-size template): sizes [3, 2, 4, 6, 8]. Slot-size values 10/12 = register, 17 = immediate/cbuf, 33 = wide third slot, -1 = unused. Slot-type 28 = register-type, 12/14 = alt, -1 = unused. Slot-flag 0 = default, 2/3/4 = secondary/uniform-extended class, -1 = unused.

Modifier Value Tables (40 arrays)

Forty .rodata arrays at 0x22FCD20–0x22FD580 (2,144 bytes total) that map an Ori-modifier enum value to a SASS field value. The lookup is TABLE[ir_val - BASE]; a -1 entry is an illegal/reserved slot (the encoder propagates -1 as an encoding error). 11 are identity maps, 4 are byte-width (wide enum spaces up to 256), 3 contain -1 gap entries.

VA	Label	type	count	identity	gaps	values
`0x22FCD20`	rounding_mode_023	dword	3	no	no	0,2,3
`0x22FCD30`	gap_table_neg1	dword	5	no	yes	0,-1,2,3,4
`0x22FCD50`	gap_table_dual_neg1	dword	6	no	yes	0,-1,1,-1,2,3
`0x22FCD70`	swap_01	dword	4	no	no	1,0,2,3
`0x22FCD80`	gap_no_3	dword	4	no	no	0,1,2,4
`0x22FCD90`	fold_last_two	dword	4	no	no	0,1,2,2
`0x22FCDA0`	large_jump_9_to_12	dword	19	no	no	0,1,2,3,4,5,6,7,8,12,13,14,15,17,18,19,20,21,22
`0x22FCDF4`	fold_3_3	dword	4	no	no	1,2,3,3
`0x22FCE1C`	complex_remapping_15	dword	15	no	yes	0,10,11,17,19,20,-1,25,26,28,42,35,12,33,34
`0x22FCE60`	alt_remapping_11	dword	11	no	no	10,11,17,19,20,21,25,26,28,34,35
`0x22FCEA4`	pair_fold_group	dword	18	no	no	0,1,1,2,3,4,5,0,1,2,3,4,5,7,8,10,11,12
`0x22FCEF4`	identity_4a	dword	4	yes	no	0,1,2,3
`0x22FCF10`	compound_remap_13	dword	13	no	no	0,1,0,1,6,7,8,17,18,19,20,21,22
`0x22FCF50`	offset_2_to_6	dword	6	no	no	0,2,3,4,5,6
`0x22FCF70`	rotation	dword	5	no	no	1,2,3,0,4
`0x22FCF90`	fold_0_1_1_2_2	dword	5	no	no	0,1,1,2,2
`0x22FCFAC`	pair_1_3	dword	2	no	no	1,3
`0x22FCFC4`	fold_2_dup	dword	9	no	no	0,1,2,2,3,4,5,6,7
`0x22FCFF0`	split_block	dword	9	no	no	0,1,2,4,5,0,3,4,5
`0x22FD020`	identity_byte_64	byte	64	yes	—	0..63
`0x22FD060`	stride_skip_byte_36	byte	36	no	—	0,1,3,4,6,7,9,10,…,52 (skip every 3rd)
`0x22FD0A0`	identity_byte_96	byte	96	yes	—	0..95
`0x22FD100`	small_identity_8	dword	8	yes	no	0..7
`0x22FD150`	skip_4	dword	6	no	no	0,1,2,3,5,6
`0x22FD170`	skip_1_3	dword	5	no	no	0,2,4,5,6
`0x22FD18C`	stride_9_then_1_4	dword	9	no	no	0,9,18,27,36,1,2,3,4
`0x22FD1B8`	fold_1_2_2_3_4	dword	5	no	no	1,2,2,3,4
`0x22FD1E0`	jump_5_to_9	dword	13	no	no	0,1,2,3,4,5,9,10,11,12,13,14,15
`0x22FD220`	identity_byte_256	byte	256	yes	—	0..255
`0x22FD320`	power_encoding_1_3_15	dword	3	no	no	1,3,15
`0x22FD354`	identity_7_plus_3	dword	10	no	no	1,2,3,4,5,6,0,1,2,3
`0x22FD384`	identity_22	dword	22	no	no	1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,0,1,2,3,4,5,7
`0x22FD3E4`	identity_17_rotated	dword	17	no	no	1..11,0,1,2,3,4,5
`0x22FD440`	identity_8_dup_tail	dword	13	no	no	0,1,2,3,4,5,6,7,2,3,4,5,6
`0x22FD480`	identity_5	dword	5	yes	no	0..4
`0x22FD498`	tristate	dword	3	yes	no	0,1,2
`0x22FD4C0`	identity_11	dword	11	yes	no	0..10
`0x22FD500`	identity_9	dword	9	yes	no	0..8
`0x22FD540`	identity_10	dword	10	yes	no	0..9
`0x22FD570`	quaternary	dword	4	yes	no	0,1,2,3

Tier-2 Per-Architecture Modifier Defaults

The Tier-2 modifier table (loaded into the encoding context at a1+404) selects per-SM encoding variations for the same Tier-1 format layout. The groups cluster by SM generation; each 16-byte slot is two {lo, hi} packed words.

Group	VA	SM range	dwords (per slot, abbreviated)
group_A_maxwell_turing	`0x202A280`	sm_50–sm_75	12 slots; `{0,1,1,1}`,`{2,1,3,1}`,`{0,1,2,1}`,`{3,1,4,1}`,`{0,2,2,2}`,`{4,2,6,2}`, then `-1`-terminated pairs
group_B_ampere_ada	`0x22F1B30`	sm_80–sm_89	`{0,2,1,1}`,`{0,1,1,2}`,`{2,1,3,2}`
group_D_lovelace_hopper	`0x22F1BA0`	sm_89–sm_90	`{1,1,3,1}`,`{0,2,2,1}`
group_E_blackwell_dc	`0x22F1AA0`	sm_100–sm_103	`{0,2,1,2}`,`{4,1,5,1}`,`{0,2,3,2}`,`{4,2,5,2}`
group_F_blackwell_consumer	`0x22F1C20`	sm_120–sm_121	`{0,4,1,4}`,`{2,4,3,4}`
group_G_cross_arch	`0x23B2DE0`	cross-architecture	`{0,1,1,4}`

The 4 appearing in the high word of every group_F slot is the consumer-Blackwell encoding-class tag; group_A uses 1/2, matching the Maxwell–Turing two-class split. These constants are the per-SM setBits triples that make the per-SM handler arrays byte-distinct while sharing the same handler bodies.

Cross-References

SASS Instruction Encoding — encoder template, bitfield packer, format descriptor architecture
SASS Encoding Dispatch Tables — the function-pointer tables and dispatch reconciliation
Instruction Selection — the ISel resolver sub_BFEBF0 and sentinel-355 handling

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