call GPU Virtual ISA NVIDIA

call Control Flow Instructions

// direct call to named function, func is a symbol
call{.uni} (ret-param), func, (param-list);

The call instruction stores the address of the next instruction, so execution can resume at that point after executing a ret instruction.

Encoding

PTX is a virtual instruction set. It has no single, stable native binary encoding - the compiler lowers this instruction to different native machine code depending on the selected NVIDIA target architecture (compute capability). This page intentionally shows no bit-diagram; see the target/version requirements below for what governs how this instruction compiles.
PTX ISA Version Introduced PTX ISA 1.0
Minimum Target sm_20

Syntax Forms

One mnemonic covers many type / state-space / scope / modifier combinations - each row below is an independently valid form.

Syntax Data Types State Space(s) Modifiers Min. Target Description
// direct call to named function, func is a symbol call{.uni} (ret-param), func, (param-list); sm_20 The call instruction stores the address of the next instruction, so execution can resume at that point after executing a ret instruction. (see the official PTX ISA docs for the full description)

Operands

At a Glance

Data Types -

Related AMDGPU Concepts

Function Call ↗
equivalent with restrictions
s_call_i64 (AMDGPU)
s_swappc_b64 (AMDGPU)

Related

More in Control Flow Instructions

Reference

NVIDIA PTX ISA

Description

The call instruction stores the address of the next instruction, so execution can resume at that point after executing a ret instruction. A call is assumed to be divergent unless the.uni suffix is present. The.uni suffix indicates that the call is guaranteed to be non-divergent, i.e. all active threads in a warp that are currently executing this instruction have identical values for the guard predicate and call target. For direct calls, the called location func must be a symbolic function name; for indirect calls, the called location fptr must be an address of a function held in a register. Input arguments and return values are optional. (see the official PTX ISA docs for the full description)

Examples

// examples of direct call
    call     init;    // call function 'init'
    call.uni g, (a);  // call function 'g' with parameter 'a'
@p  call     (d), h, (a, b);  // return value into register d

// call-via-pointer using jump table
// (truncated - see the official PTX ISA docs for the full example)

Reproduced from NVIDIA's official PTX ISA documentation for technical accuracy.

Sources