v_cvt_u32_f32 GPU Native ISA AMD Vector

Vector Arithmetic

v_cvt_u32_f32

Convert from a single-precision float input to an unsigned 32-bit integer value and store the result into a vector register.

Encoding

Binary Layout (AMD CDNA 5)
0111111
31:25
VDST
24:17
unassigned
16
0000111
15:9
SRC0
8:0
 

The ENC_VOP1 layout from AMD's machine-readable ISA specification (AMD CDNA 5). Opcode 7 in OP rebuilds 0x7E000E00, an identifier AMD lists for this encoding. Bits marked unassigned have no field in the specification. Not the same in every generation: AMD CDNA 4 (field layout), AMD CDNA 3 (field layout), AMD CDNA 2 (field layout), AMD CDNA 1 (field layout), AMD RDNA 3.5 (field layout), AMD RDNA 3 (field layout), AMD RDNA 2 (field layout), AMD RDNA 1 (field layout). The same in AMD RDNA 4.

Format VOP1
Width 32 bits
Opcode 7
Identifier 0x7E000E00

Operands

  • VDST
    Written. Operand must be a vector GPR. Uses an 8-bit operand field. Data format: Unsigned 32-bit integral data. (OPR_VGPR, FMT_NUM_U32)
  • SRC0
    Read. All operands. Covers all operands that are allowed as scalar or vector sources. Data format: 32-bit single-precision floating point value. (OPR_SRC, FMT_NUM_F32)

In AMD's order, as its machine-readable ISA specification lists them for the ENC_VOP1 encoding (AMD CDNA 5).

GFX Target Compatibility

TargetSupport
gfx1100✅ Supported

1ULP accuracy, out-of-range floating point values (including infinity) saturate. NAN is converted to 0. Generation of the INEXACT exception is controlled by the CLAMP bit. INEXACT exceptions are enabled for this conversion iff CLAMP == 1.

Related

More in Vector Arithmetic

Reference

AMDGPU / GFX ISA

Semantics

D0.u32 = f32_to_u32(S0.f32)

Example

v_cvt_u32_f32 v5, v1

A real instruction accepted by the LLVM assembler, taken verbatim from LLVM's own AMDGPU MC test suite. Not from an AMD document, and not authored here.

Sources