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9.2 Location Specifications

Several GDB commands accept arguments that specify a location or locations of your program’s code. Many times locations are specified using a source line number, but they can also be specified by a function name, an address, a label, etc. The different forms of specifying a location that GDB recognizes are collectively known as forms of location specification, or location spec. This section documents the forms of specifying locations that GDB recognizes.

When you specify a location, GDB needs to find the place in your program, known as code location, that corresponds to the given location spec. We call this process of finding actual code locations corresponding to a location spec location resolution.

A concrete code location in your program is uniquely identifiable by a set of several attributes: its source line number, the name of its source file, the fully-qualified and prototyped function in which it is defined, and an instruction address. Because each inferior has its own address space, the inferior number is also a necessary part of these attributes.

By contrast, location specs you type will many times omit some of these attributes. For example, it is customary to specify just the source line number to mean a line in the current source file, or specify just the basename of the file, omitting its directories. In other words, a location spec is usually incomplete, a kind of blueprint, and GDB needs to complete the missing attributes by using the implied defaults, and by considering the source code and the debug information available to it. This is what location resolution is about.

The resolution of an incomplete location spec can produce more than a single code location, if the spec doesn’t allow distinguishing between them. Here are some examples of situations that result in a location spec matching multiple code locations in your program:

Resolution of a location spec can also fail to produce a complete code location, or even fail to produce any code location. Here are some examples of such situations:

Locations may be specified using three different formats: linespec locations, explicit locations, or address locations. The following subsections describe these formats.

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