Manual Reference Pages  - UPCDECL (1)


upcdecl - UPC type explanation and construction tool, version 0.6




upcdecl [options] [ explain | declare | cast | files... ]


upcdecl is a simple tool based off the original cdecl tool written in the late 80’s by Graham Ross et al. upcdecl is a text-based tool with two main modes of operation: translating english versions of UPC declarations to UPC code, and vice versa. upcdecl accepts commands using a very simple grammar, such as ‘explain int c’ or ‘declare c as pointer to shared int’. Typing ‘help’ with no arguments inside upcdecl will display a simplified version of the grammar the tool uses, or see the mygram.txt file in the installation directory for the full grammar. See the EXAMPLES section for more example usage.

If files given on the command line start with explain, declare, cast, or set, the rest of the input on the command line is interpreted as a command instead of a set of filenames. Otherwise, each file is opened and the contents of the file are interpreted as upcdecl commands.

There are six statements in the language. The declare statement composes a UPC type declaration from a verbose description. The cast statement composes a UPC type cast as might appear in an expression. The explain statement decodes a UPC type declaration or cast, producing a verbose description. The help (or ?) statement provides a help message. The quit (or exit) statement (or the end of file) exits the program. The set statement allows the command line options to be set interactively. Each statement is separated by a semicolon or a newline.


See this message.
Suppress upcdecl> prompt. Equivalent to the "quiet" set option.
Don’t use Term::ReadLine for input. Use this option if you have problems with the Perl-based ReadLine that is bundled with the program. Typing ‘set’ with no arguments at the upcdecl prompt will tell you which module is being used for input.
Disable spaces around pointers in C output. (Eg, "declare f as pointer to pointer to int" -> "int **f" instead of "int * * f".) Equivalent to the "nopointerspaces" set option.
Create compilable output. Adds ; to variable declarations and {} to function declarations in "declare" output. Equivalent to the "create" set option.
-t <test file>
Test using file as input. The test file should have the following format for each line: input | expected output. Not useful for end users.
Verbose UPC english explanations. Include implicit "local" in english output ("explain int c" -> "declare c as local int"). Equivalent to the "upcverbose" set option.
Show upcdecl version and exit.


To have upcdecl display UPC code for an English description, use the ‘declare’ statement:

upcdecl> declare f as const int
const int f

You can use ‘pointer to’, ‘array of’, and ‘function returning’ to make arbitrarily complex definitions:

upcdecl> declare f as pointer to array of function returning pointer to volatile int
volatile int * (* f)[]()
Use the ‘shared’ keyword to have upcdecl return UPC declarations:

upcdecl> declare f as shared array 55 of int
shared [1] int f[55]

When followed by ‘blocksize’, the ‘shared‘ keyword also takes arbitrary numerical blocksizes or one of ‘automatic’, ‘cyclic’, ‘indefinite’:

upcdecl> declare f as shared blocksize 5 pointer to shared blocksize indefinite pointer to function returning shared blocksize cyclic int
shared [1] int (* shared [] * shared [5] f)()

Additionally, the ‘cast’ statement may be used to show how to perform a cast:

upcdecl> cast c into shared blocksize indefinite int
(shared [] int)c

To make sense of a UPC declaration, use the ‘explain’ command:

upcdecl> explain shared [4] int (*f)(int, int, int)
declare f as pointer to function (int, int, int) returning shared (blocksize 4) int

upcdecl> explain shared [] int *const shared c
declare c as const shared (blocksize cyclic) pointer to shared (blocksize indefinite) int


As in the original cdecl tool, the English syntax is very verbose.

There are even less semantic checks done for upcdecl than the original cdecl.

The tool accepts "shared void f" as a valid C declaration.

The cdecl grammar used as a basis for upcdecl was written before the ANSI C standard was completed (and well before ISO C99 was finished). Some attempt has been made to update the grammar to accept valid ISO C99 code, but there are undoubtedly bits of valid code that will be rejected by the parser.

upcdecl will parse many simple arithmetic expressions inside blocksize declarations or array dimensions, but does not understand function calls, sizeof operators, struct accesses, relational/boolean operators, bitwise operators, conditional expressions, increment/decrement operators, floating point literals or type cast sub-expressions.

There should be an array visualization feature to show how a shared array will be distributed among threads.


Adam Leko, with significant contributions and guidance from Dan Bonachea and the rest of the Berkeley UPC team.


upcdecl is heavily based on the grammar specified in the original cdecl man page.

Credits for the original cdecl tool:

Originally written by Graham Ross, improved and expanded by David Wolverton,
Tony Hansen, and Merlyn LeRoy. GNU readline support and Linux port by David
R. Conrad, <[email protected]>.


We are interested in fixing any bugs that exist in upcdecl. For bug reporting instructions, please go to

Berkeley UPC UPCDECL (1) October 2022
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