---
name: "dwarf_get_fde_info_for_reg"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/dwarf_get_fde_info_for_reg"
---

# dwarf\_get\_fde\_info\_for\_reg(3)

retrieve register rule

## NAME

**dwarf\_get\_fde\_info\_for\_reg** – retrieve register rule

## LIBRARY

library “libdwarf”

## SYNOPSIS

**#include \<libdwarf.h\>**

*int*\

**dwarf\_get\_fde\_info\_for\_reg**(*Dwarf\_Fde fde*, *Dwarf\_Half table\_column*, *Dwarf\_Addr pc*, *Dwarf\_Signed \*offset\_relevant*, *Dwarf\_Signed \*register\_num*, *Dwarf\_Signed \*offset*, *Dwarf\_Addr \*row\_pc*, *Dwarf\_Error \*error*);

## DESCRIPTION

Function **dwarf\_get\_fde\_info\_for\_reg**() retrieves a register rule from the register rule table associated with a given FDE descriptor, given a program counter address and rule column number.

Argument *fde* should reference a valid DWARF FDE descriptor.

Arugment *table\_column* should hold the column number of the register rule desired.

Argument *pc* should hold the program counter address to be used to locate the desired register rule row.

On successful execution, **dwarf\_get\_fde\_info\_for\_reg**() stores information about the register rule found into the locations pointed to by the arguments *offset\_relevant*, *register\_num*, *offset* and *row\_pc*.

If there is an offset value associated with the register rule, the location pointed to by argument *offset\_relevant* will be set to 1.

Argument *register\_num* should point to a location which will hold the register number associated with the register rule.

Argument *offset* should point to a location which will be set to the offset value associated with the register rule, or to 0 if the register rule does not have an offset value.

Argument *row\_pc* should point to a location which will be set to the lowest program counter address associated with the register rule found.

If argument *err* is not NULL, it will be used to return an error descriptor in case of an error.

### COMPATIBILITY

Function **dwarf\_get\_fde\_info\_for\_reg**() is deprecated since it only supports DWARF2 frame sections. Applications should instead use function [dwarf\_get\_fde\_info\_for\_reg3(3)](/dwarf_get_fde_info_for_reg3/3.md) which supports both DWARF2 and DWARF3 frame sections.

## RETURN VALUES

Function **dwarf\_get\_fde\_info\_for\_reg**() returns DW\_DLV\_OK when it succeeds. In case of an error, it returns DW\_DLV\_ERROR and sets the argument *err*.

## ERRORS

Function **dwarf\_get\_fde\_info\_for\_reg**() can fail with:

- \[DW\_DLE\_ARGUMENT\]

  One of the arguments *fde*, *offset\_relevant*, *register\_num*, *offset* or *row\_pc* was NULL.

- \[DW\_DLE\_FRAME\_TABLE\_COL\_BAD\]

  The column number provided in argument *table\_column* was too large.

- \[DW\_DLE\_PC\_NOT\_IN\_FDE\_RANGE\]

  The program counter value provided in argument *pc* did not fall in the range covered by argument *fde*.

## SEE ALSO

[dwarf(3)](/dwarf/3.md), [dwarf\_get\_fde\_at\_pc(3)](/dwarf_get_fde_at_pc/3.md), [dwarf\_get\_fde\_info\_for\_all\_regs(3)](/dwarf_get_fde_info_for_all_regs/3.md), [dwarf\_get\_fde\_info\_for\_all\_regs3(3)](/dwarf_get_fde_info_for_all_regs3/3.md), [dwarf\_get\_fde\_info\_for\_cfa\_reg3(3)](/dwarf_get_fde_info_for_cfa_reg3/3.md), [dwarf\_get\_fde\_info\_for\_reg3(3)](/dwarf_get_fde_info_for_reg3/3.md), [dwarf\_get\_fde\_n(3)](/dwarf_get_fde_n/3.md), [dwarf\_set\_frame\_cfa\_value(3)](/dwarf_set_frame_cfa_value/3.md), [dwarf\_set\_frame\_rule\_initial\_value(3)](/dwarf_set_frame_rule_initial_value/3.md), [dwarf\_set\_frame\_rule\_table\_size(3)](/dwarf_set_frame_rule_table_size/3.md), [dwarf\_set\_frame\_same\_value(3)](/dwarf_set_frame_same_value/3.md), [dwarf\_set\_frame\_undefined\_value(3)](/dwarf_set_frame_undefined_value/3.md)