llvm-mirror/docs/CommandGuide/llvm-diff.rst
James Henderson f75dcd7d67 [docs][tools] Add missing "program" tags to rst files
Sphinx allows for definitions of command-line options using
`.. option <name>` and references to those options via `:option:<name>`.
However, it looks like there is no scoping of these options by default,
meaning that links can end up pointing to incorrect documents. See for
example the llvm-mca document, which contains references to -o that,
prior to this patch, pointed to a different document. What's worse is
that these links appear to be non-deterministic in which one is picked
(on my machine, some references end up pointing to opt, whereas on the
live docs, they point to llvm-dwarfdump, for example).

The fix is to add the .. program <name> tag. This essentially namespaces
the options (definitions and references) to the named program, ensuring
that the links are kept correct.

Reviwed by: andreadb

Differential Revision: https://reviews.llvm.org/D63873

llvm-svn: 364538
2019-06-27 13:24:46 +00:00

58 lines
1.6 KiB
ReStructuredText

llvm-diff - LLVM structural 'diff'
==================================
.. program:: llvm-diff
SYNOPSIS
--------
**llvm-diff** [*options*] *module 1* *module 2* [*global name ...*]
DESCRIPTION
-----------
**llvm-diff** compares the structure of two LLVM modules, primarily
focusing on differences in function definitions. Insignificant
differences, such as changes in the ordering of globals or in the
names of local values, are ignored.
An input module will be interpreted as an assembly file if its name
ends in '.ll'; otherwise it will be read in as a bitcode file.
If a list of global names is given, just the values with those names
are compared; otherwise, all global values are compared, and
diagnostics are produced for globals which only appear in one module
or the other.
**llvm-diff** compares two functions by comparing their basic blocks,
beginning with the entry blocks. If the terminators seem to match,
then the corresponding successors are compared; otherwise they are
ignored. This algorithm is very sensitive to changes in control flow,
which tend to stop any downstream changes from being detected.
**llvm-diff** is intended as a debugging tool for writers of LLVM
passes and frontends. It does not have a stable output format.
EXIT STATUS
-----------
If **llvm-diff** finds no differences between the modules, it will exit
with 0 and produce no output. Otherwise it will exit with a non-zero
value.
BUGS
----
Many important differences, like changes in linkage or function
attributes, are not diagnosed.
Changes in memory behavior (for example, coalescing loads) can cause
massive detected differences in blocks.