pto.settf32mode¶

pto.settf32mode is part of the Sync And Config instruction set.

Summary¶

Configure TF32 transform mode for FP32 matrix-multiplication and convolution paths. This programs the CCE (Cube Compute Engine) TF32 mode register.

On A2/A3, TF32 is not supported and pto.settf32mode is a no-op; the enable flag is ignored and no mode state is established. On A5, when enable = true, the backend configures the CCE to use TF32 mantissa truncation (7-bit mantissa) for subsequent FP32 matrix-multiplication and convolution paths; the mode field selects the rounding behavior. On the CPU simulator, pto.settf32mode is a functional no-op that preserves the mode state in software.

This instruction controls backend-specific TF32 transformation behavior used by supported compute paths. It is part of the tile synchronization or configuration shell, so the visible effect is ordering or state setup rather than arithmetic payload transformation.

No direct tensor arithmetic is produced by this instruction. It updates target mode state used by subsequent instructions.

Syntax¶

Textual spelling is defined by the PTO ISA syntax-and-operands pages.

Schematic form:

pto.settf32mode {enable = true, mode = ...}

IR Level 1 (SSA)¶

pto.settf32mode {enable = true, mode = ...}

IR Level 2 (DPS)¶

pto.settf32mode ins({enable = true, mode = ...}) outs()

C++ Intrinsic¶

Declared in include/pto/common/pto_instr.hpp:

template <bool isEnable, RoundMode tf32TransMode = RoundMode::CAST_ROUND, typename... WaitEvents>
PTO_INST RecordEvent SETTF32MODE(WaitEvents &... events);

Inputs¶

Operand	Type	Description
`enable`	`bool`	Enables (`true`) or disables (`false`) the TF32 transform mode
`mode`	`RoundMode`	TF32 rounding mode; `CAST_ROUND` rounds to nearest even; other modes are reserved

Expected Outputs¶

This form is defined primarily by its ordering or configuration effect. It does not introduce a new payload tile.

Side Effects¶

A2/A3: No-op. TF32 is not supported; no architectural state is affected.
A5: Configures the CCE TF32 mode register. Affects the precision of subsequent FP32 matrix/convolution compute.
CPU simulator: Updates software-simulation mode state; does not affect IEEE 754 rounding.

Constraints¶

Constraints

On A2/A3, calling pto.settf32mode is legal but has no effect.
On A5, enable must be true or false and mode must be a supported RoundMode (only CAST_ROUND is currently defined).
On CPU simulator, any combination of enable and mode is accepted without error.
This instruction has control-state side effects and should be ordered appropriately relative to dependent compute instructions.

Cases That Are Not Allowed¶

Cases That Are Not Allowed

Relying on TF32 precision behavior on A2/A3 (not supported).
Using modes other than CAST_ROUND (reserved/undefined).

Examples¶

#include <pto/pto-inst.hpp>
using namespace pto;

void example_enable_tf32() {
  SETTF32MODE<true, RoundMode::CAST_ROUND>();
}