.\" Process with groff -man -Tascii file.3 .TH GMQCC 1 2012-07-12 "" "gmqcc Manual" .SH NAME gmqcc \- A Quake C compiler built from the NIH realm of sarcastic wit .SH SYNOPSIS .B gmqcc [\fIOPTIONS\fR] [\fIfiles...\fR] .SH DESCRIPTION Traditionally, a QC compiler reads the file \fIprogs.src\fR which in its first line contains the output filename, and the rest is a list of QC source files that are to be compiled in order. \fBgmqcc\fR optionally takes options to specify the output and input files on the commandline, and also accepts assembly files. .SH OPTIONS \fBgmqcc\fR mostly tries to mimic gcc's commandline handling, though there are also traditional long-options available. .TP .B "-h, --help" Show a usage message and exit. .TP .B "-debug" Turn on some compiler debugging mechanisms. .TP .B "-memchk" Turn on compiler mem-check. (Shows allocations and checks for leaks.) .TP .BI "-o, --output=" filename Specify the output filename. Defaults to progs.dat. This will overwrite the output file listed in a \fIprogs.src\fR file in case such a file is used. .TP .BI "-O" number Specify the optimization level .RS .IP 3 Highest optimization level .IP 2 Default optimization level .IP 1 Minimal optimization level .IP 0 Disable optimization entirely .RE .TP .BI "-O" name "\fR, " "" -Ono- name Enable or disable a specific optimization. Note that these options must be used after setting the optimization level, otherwise they'll be overwritten. .TP .B -Ohelp List all possible optimizations and the optimization level they're activated at. .TP .BR -q ", " --quiet Be less verbose. In particular removes the messages about which files are being processed, and which compilation mode is being used, and some others. Warnings and errors will of course still be displayed. .TP .BI -W warning "\fR, " "" -Wno- warning Enable or disable a warning. .TP .B -Wall Enable almost all warnings. Overrides preceding -W parameters. .sp The following warnings will \fBnot\fR be anbled: .in +4 .nf -Wuninitialized-global .fi .in .TP .BR -Werror ", " -Wno-error Controls whether or not all warnings should be treated as errors. .TP .BI -Werror- warning "\fR, " "" -Wno-error- warning Controls whether a specific warning should be an error. .TP .B -Whelp List all possible warn flags. .TP .BI -f flag "\fR, " "" -fno- flag Enable or disable a specific compile flag. See the list of flags below. .TP .B -fhelp List all possible compile flags. .TP .B -nocolor Disables colored output .TP .BI -config= file Use an ini file to read all the -O, -W and -f flag from. See the CONFIG section about the file format. .TP .BI "-redirout=" file Redirects standard output to a \fIfile\fR .TP .BI "-redirerr=" file Redirects standard error to a \fIfile\fR .TP .BI "-std=" standard Use the specified standard for parsing QC code. The following standards are available: .IR gmqcc , qcc , fteqcc Selecting a standard also implies some -f options and behaves as if those options have been written right after the -std option, meaning if you changed them before the -std option, you're now overwriting them. .sp .BR -std=gmqcc " includes:" .in +4 .nf -fadjust-vector-fields -fcorrect-logic -ftrue-empty-strings -floop-labels -finitialized-nonconstants -ftranslatable-strings -f\fIno-\fRfalse-empty-strings -Winvalid-parameter-count -Wmissing-returnvalues -fcorrect-ternary (cannot be turned off) .fi .in .sp .BR -std=qcc " includes:" .in +4 .nf -fassign-function-types -f\fIno-\fRadjust-vector-fields .fi .in .sp .BR -std=fteqcc " includes:" .in +4 .nf -fftepp -ftranslatable-strings -fassign-function-types -Wternary-precedence -f\fIno-\fRadjust-vector-fields -f\fIno-\fRcorrect-ternary .fi .in .TP .B "-dump" DEBUG OPTION. Print the code's intermediate representation before the optimization and finalization passes to stdout before generating the binary. .TP .B "-dumpfin" DEBUG OPTION. Print the code's intermediate representation after the optimization and finalization passes to stdout before generating the binary. The instructions will be enumerated, and values will contain a list of liferanges. .SH COMPILE WARNINGS .TP .B -Wunused-variable Generate a warning about variables which are declared but never used. This can be avoided by adding the \fInoref\fR keyword in front of the variable declaration. Additionally a complete section of unreferenced variables can be opened using \fI#pragma noref 1\fR, and closed via \fI#pragma noref 0\fR. .TP .B -Wused-uninitialized Generate a warning if it is possible that a variable can be used without prior initialization. Note that this warning is not necessarily reliable if the initialization happens only under certain conditions. The other way is \fInot\fR possible: that the warning is \fInot\fR generated when uninitialized use \fIis possible\fR. .TP .B -Wunknown-control-sequence Generate an error when an unrecognized control sequence in a string is used. Meaning: when there's a character after a backslash in a string which has no known meaning. .TP .B -Wextensions Warn when using special extensions which are not part of the selected standard. .TP .B -Wfield-redeclared Generally QC compilers ignore redeclaration of fields. Here you can optionally enable a warning. .TP .B -Wmissing-return-values Functions which aren't of type \fIvoid\fR will warn if it possible to reach the end without returning an actual value. .TP .B -Winvalid-parameter-count Warn about a function call with an invalid number of parameters. .TP .B -Wlocal-shadows Warn when a locally declared variable shadows variable. .TP .B -Wlocal-constants Warn when the initialization of a local variable turns the variable into a constant. This is default behaviour unless \fI-finitialized-nonconstants\fR is used. .TP .B -Wvoid-variables There are only 2 known global variables of type void: end_sys_globals and end_sys_fields. Any other void-variable will warn. .TP .B -Wimplicit-function-pointer A global function which is not declared with the \fIvar\fR keyword is expected to have an implementing body, or be a builtin. If neither is the case, it implicitly becomes a function pointer, and a warning is generated. .TP .B -Wvariadic-function Currently there's no way for an in QC implemented function to access variadic parameters. If a function with variadic parameters has an implementing body, a warning will be generated. .TP .B -Wframe-macros Generate warnings about \fI$frame\fR commands, for instance about duplicate frame definitions. .TP .B -Weffectless-statement Warn about statements which have no effect. Any expression which does not call a function or assigns a variable. .TP .B -Wend-sys-fields The \fIend_sys_fields\fR variable is supposed to be a global variable of type \fIvoid\fR. It is also recognized as a \fIfield\fR but this will generate a warning. .TP .B -Wassign-function-types Warn when assigning to a function pointer with an unmatching signature. This usually happens in cases like assigning the null function to an entity's .think function pointer. .TP .B -Wpreprocessor Enable warnings coming from the preprocessor. Like duplicate macro declarations. This warning triggers when there's a problem with the way the preprocessor has been used, it will \fBnot\fR affect warnings generated with the '#warning' directive. See -Wcpp. .TP .B -Wcpp Show warnings created using the preprocessor's '#warning' directive. .TP .B -Wmultifile-if Warn if there's a preprocessor \fI#if\fR spanning across several files. .TP .B -Wdouble-declaration Warn about multiple declarations of globals. This seems pretty common in QC code so you probably do not want this unless you want to clean up your code. .TP .B -Wconst-var The combination of \fIconst\fR and \fIvar\fR is not illegal, however different compilers may handle them differently. We were told, the intention is to create a function-pointer which is not assignable. This is exactly how we interpret it. However for this interpretation the \fIvar\fR keyword is considered superfluous (and philosophically wrong), so it is possible to generate a warning about this. .TP .B -Wmultibyte-character Warn about multibyte character constants, they do not work right now. .TP .B -Wternary-precedence Warn if a ternary expression which contains a comma operator is used without enclosing parenthesis, since this is most likely not what you actually want. We recommend the \fI-fcorrect-ternary\fR option. .TP .B -Wunknown-pragmas Warn when encountering an unrecognized \fI#pragma\fR line. .TP .B -Wunreachable-code Warn about unreachable code. That is: code after a return statement, or code after a call to a function marked as 'noreturn'. .TP .B -Wdebug Enable some warnings added in order to help debugging in the compiler. You won't need this. .B -Wunknown-attribute Warn on an unknown attribute. The warning will inlclude only the first token inside the enclosing attribute-brackets. This may change when the actual attribute syntax is better defined. .TP .B -Wreserved-names Warn when using reserved names such as 'nil'. .TP .B -Wuninitialized-constant Warn about global constants (using the 'const' keyword) with no assigned value. .TP .B -Wuninitialized-global Warn about global variables with no initializing value. This is off by default, and is added mostly to help find null-values which are supposed to be replaced by the untyped 'nil' constant. .TP .B -Wdifferent-qualifiers Warn when a variables is redeclared with a different qualifier. For example when redeclaring a variable as \'var\' which was previously marked \'const\'. .TP .B -Wdifferent-attributes Similar to the above but for attributes like "[[noreturn]]". .TP .B -Wdeprecated Warn when a function is marked with the attribute "[[deprecated]]". This flag enables a warning on calls to functions marked as such. .TP .B -Wparenthesis Warn about possible mistakes caused by missing or wrong parenthesis, like an assignment in an 'if' condition when there's no additional set of parens around the assignment. .SH COMPILE FLAGS .TP .B -fdarkplaces-string-table-bug Add some additional characters to the string table in order to compensate for a wrong boundcheck in some specific version of the darkplaces engine. .TP .B -fadjust-vector-fields When assigning to field pointers of type \fI.vector\fR the common behaviour in compilers like \fIfteqcc\fR is to only assign the x-component of the pointer. This means that you can use the vector as such, but you cannot use its y and z components directly. This flag fixes this behaviour. Before using it make sure your code does not depend on the buggy behaviour. .TP .B -fftepp Enable a partially fteqcc-compatible preprocessor. It supports all the features used in the Xonotic codebase. If you need more, write a ticket. .TP .B -fftepp-predefs Enable some predefined macros. This only works in combination with \'-fftepp' and is currently not included by '-std=fteqcc'. The following macros will be added: .in +4 .nf __LINE__ __FILE__ __COUNTER__ __COUNTER_LAST__ __RANDOM__ __RANDOM_LAST__ __DATE__ __TIME__ .fi .in Note that fteqcc also defines __NULL__ which is not implemented yet. (See -funtyped-nil about gmqcc's alternative to __NULL__). .TP .B -frelaxed-switch Allow switch cases to use non constant variables. .TP .B -fshort-logic Perform early out in logical AND and OR expressions. The final result will be either a 0 or a 1, see the next flag for more possibilities. .TP .B -fperl-logic In many languages, logical expressions perform early out in a special way: If the left operand of an AND yeilds true, or the one of an OR yields false, the complete expression evaluates to the right side. Thus \fItrue && 5\fI evaluates to 5 rather than 1. .TP .B -ftranslatable-strings Enable the underscore intrinsic: Using \fI_("A string constant")\fR will cause the string immediate to get a name with a "dotranslate_" prefix. The darkplaces engine recognizes these and translates them in a way similar to how gettext works. .TP .B -finitialized-nonconstants Don't implicitly convert initialized variables to constants. With this flag, the \fIconst\fR keyword is required to make a constant. .TP .B -fassign-function-types If this flag is not set, (and it is set by default in the qcc and fteqcc standards), assigning function pointers of mismatching signatures will result in an error rather than a warning. .TP .B -flno Produce a linenumber file along with the output .dat file. .TP .B -fcorrect-ternary Use C's operator precedence for ternary expressions. Unless your code depends on fteqcc-compatible behaviour, you'll want to use thi soption. .TP .B -fsingle-vector-defs Normally vectors generate 4 defs, once for the vector, and once for its components with _x, _y, _z suffixes. This option prevents components from being listed. .TP .B -fcorrect-logic Most QC compilers translate if(a_vector) directly as an IF on the vector, which means only the x-component is checked. This causes vectors to be cast to actual booleans via a NOT_V and, if necessary, a NOT_F chained to it. .in +4 .nf if (a_vector) // becomes if not(!a_vector) // likewise a = a_vector && a_float // becomes a = !!a_vector && a_float .fi .in .TP .B -ftrue-empty-strings An empty string is considered to be true everywhere. The NOT_S instruction usually considers an empty string to be false, this option effectively causes the unary not in strings to use NOT_F instead. .TP .B -ffalse-empty-strings An empty string is considered to be false everywhere. This means loops and if statements which depend on a string will perform a NOT_S instruction on the string before using it. .TP .B -futf8 Enable utf8 characters. This allows utf-8 encoded character constants, and escape sequence codepoints in the valid utf-8 range. Effectively enabling escape sequences like '\\{x2211}'. .TP .B -fbail-on-werror When a warning is treated as an error, and this option is set (which it is by default), it is like any other error and will cause compilation to stop. When disabling this flag by using \-fno-bail-on-werror, compilation will continue until the end, but no output is generated. Instead the first such error message's context is shown. .TP .B -floop-labels Allow loops to be labeled, and allow 'break' and 'continue' to take an optional label to decide which loop to actually jump out of or continue. .sp .in +4 .nf for :outer (i = 0; i < n; ++i) { while (inner) { ...; if (something) continue outer; } } .fi .in .TP .B -funtyped-nil Adds a global named 'nil' which is of no type and can be assigned to anything. No typechecking will be performed on assignments. Assigning to it is forbidden, using it in any other kind of expression is also not allowed. .sp Note that this is different from fteqcc's __NULL__: In fteqcc, __NULL__ maps to the integer written as '0i'. It's can be assigned to function pointers and integers, but it'll error about invalid instructions when assigning it to floats without enabling the FTE instruction set. There's also a bug which allows it to be assigned to vectors, for which the source will be the global at offset 0, meaning the vector's y and z components will contain the OFS_RETURN x and y components. .sp In that gmqcc the nil global is an actual global filled with zeroes, and can be assigned to anything including fields, vectors or function pointers, and they end up becoming zeroed. .TP .B -fpermissive Various effects, usually to weaken some conditions. .RS .IP "with -funtyped-nil" Allow local variables named 'nil'. (This will not allow declaring a global of that name.) .SH OPTIMIZATIONS .TP .B -Opeephole Some general peephole optimizations. For instance the code `a = b + c` typically generates 2 instructions, an ADD and a STORE. This optimization removes the STORE and lets the ADD write directly into A. .TP .B -Otail-recursion Tail recursive function calls will be turned into loops to avoid the overhead of the CALL and RETURN instructions. .TP .B -Ooverlap-locals Make all functions which use neither local arrays nor have locals which are seen as possibly uninitialized use the same local section. This should be pretty safe compared to other compilers which do not check for uninitialized values properly. The problem is that there's QC code out there which really doesn't initialize some values. This is fine as long as this kind of optimization isn't used, but also, only as long as the functions cannot be called in a recursive manner. Since it's hard to know whether or not an array is actually fully initialized, especially when initializing it via a loop, we assume functions with arrays to be too dangerous for this optimization. .TP .B -Olocal-temps This promotes locally declared variables to "temps". Meaning when a temporary result of an operation has to be stored somewhere, a local variable which is not 'alive' at that point can be used to keep the result. This can reduce the size of the global section. This will not have declared variables overlap, even if it was possible. .TP .B -Oglobal-temps Causes temporary values which do not need to be backed up on a CALL to not be stored in the function's locals-area. With this, a CALL to a function may need to back up fewer values and thus execute faster. .TP .B -Ostrip-constant-names Don't generate defs for immediate values or even declared constants. Meaning variables which are implicitly constant or qualified as such using the 'const' keyword. .TP .B -Ooverlap-strings Aggressively reuse strings in the string section. When a string should be added which is the trailing substring of an already existing string, the existing string's tail will be returned instead of the new string being added. For example the following code will only generate 1 string: .in +4 .nf print("Hell you!\\n"); print("you!\\n"); // trailing substring of "Hello you!\\n" .fi .in There's however one limitation. Strings are still processed in order, so if the above print statements were reversed, this optimization would not happen. .TP .B -Ocall-stores By default, all parameters of a CALL are copied into the parameter-globals right before the CALL instructions. This is the easiest and safest way to translate calls, but also adds a lot of unnecessary copying and unnecessary temporary values. This optimization makes operations which are used as a parameter evaluate directly into the parameter-global if that is possible, which is when there's no other CALL instruction in between. .TP .B -Ovoid-return Usually an empty RETURN instruction is added to the end of a void typed function. However, additionally after every function a DONE instruction is added for several reasons. (For example the qcvm's disassemble switch uses it to know when the function ends.). This optimization replaces that last RETURN with DONE rather than adding the DONE additionally. .TP .B -Ovector-components Because traditional QC code doesn't allow you to access individual vector components of a computed vector without storing it in a local first, sometimes people multiply it by a constant like '0 1 0' to get, in this case, the y component of a vector. This optimization will turn such a multiplication into a direct component access. If the factor is anything other than 1, a float-multiplication will be added, which is still faster than a vector multiplication. .SH CONFIG The configuration file is similar to regular .ini files. Comments start with hashtags or semicolons, sections are written in square brackets and in each section there can be arbitrary many key-value pairs. .sp There are 3 sections currently: .IR flags ", " warnings ", and " optimizations . They contain a list of boolean values of the form `VARNAME = true` or `VARNAME = false`. The variable names are the same as for the corresponding -W, -f or -O flag written with only capital letters and dashes replaced by underscores. .sp Here's an example: .in +4 .nf # a GMQCC configuration file [flags] FTEPP = true ADJUST_VECTOR_FIELDS = false LNO = true [warnings] UNUSED_VARIABLE = false USED_UNINITIALIZED = true [optimizations] PEEPHOLE = true TAIL_RECURSION = true .fi .in .SH BUGS Currently the '-fftepp-predefs' flag is not included by '-std=fteqcc', partially because it is not entirely conformant to fteqcc. .sp Please report bugs on , or see on how to contact us. .SH FILES .TP 20 .B gmqcc.ini.example A documented example for a gmqcc.ini file. .SH SEE ALSO .IR qcvm (1) .SH AUTHOR See .