RVOPcode
Back To Register BrowserView ABI / Calling Convention
Register Guide

RISC-V fcsr / fcsr Register: Floating-point control/status CSR

fcsr is a floating-point control/status entry associated with rounding mode and accrued exception flags.

ABI name: fcsr; physical register: fcsr.
Save rule: Thread storage duration (psABI requirement).
Read it through its psABI role first, then inspect how each instruction reads or writes it.
Physical Name fcsrABI Name fcsrSave Rule Thread storage duration (psABI requirement)
Role
Floating-point control/status CSR
Convention
psABI: fcsr must have thread storage duration
Remember This First
The calling convention listed for this entry is: psABI: fcsr must have thread storage duration.
RISC-V Floating-Point ISA Reference

ABI register

fcsr is a floating-point control/status entry associated with rounding mode and accrued exception flags.

Preserved across calls: Thread storage duration (psABI requirement)
RISC-V Unprivileged ISA Manual, floating-point CSRs

When It Fits Best

  • - Use it according to the documented role: Floating-point control/status CSR.
  • - Consult the applicable ISA or ABI specification for concrete read, write, or execution semantics.

When Not To Use It This Way

  • - Do not apply the integer temporary-register t* rules to this entry.
  • - Do not infer behavior not defined by this page or the applicable specification from the ABI name.

What Happens Around A Call

1

The calling convention listed for this entry is: psABI: fcsr must have thread storage duration.

2

The save rule listed for this entry is: Thread storage duration (psABI requirement).

Read The Documented Role

Examples explain the rule, not a complete program
# fcsr / fcsr
# Floating-point control/status CSR
# psABI: fcsr must have thread storage duration