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diff --git a/share/doc/gccint/Stack-Arguments.html b/share/doc/gccint/Stack-Arguments.html new file mode 100644 index 0000000..015f0d0 --- /dev/null +++ b/share/doc/gccint/Stack-Arguments.html @@ -0,0 +1,264 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). 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Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>GNU Compiler Collection (GCC) Internals: Stack Arguments</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Stack Arguments"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Stack Arguments"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Stack-and-Calling.html#Stack-and-Calling" rel="up" title="Stack and Calling"> +<link href="Register-Arguments.html#Register-Arguments" rel="next" title="Register Arguments"> +<link href="Elimination.html#Elimination" rel="previous" title="Elimination"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Stack-Arguments"></a> +<div class="header"> +<p> +Next: <a href="Register-Arguments.html#Register-Arguments" accesskey="n" rel="next">Register Arguments</a>, Previous: <a href="Elimination.html#Elimination" accesskey="p" rel="previous">Elimination</a>, Up: <a href="Stack-and-Calling.html#Stack-and-Calling" accesskey="u" rel="up">Stack and Calling</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Passing-Function-Arguments-on-the-Stack"></a> +<h4 class="subsection">18.9.6 Passing Function Arguments on the Stack</h4> +<a name="index-arguments-on-stack"></a> +<a name="index-stack-arguments"></a> + +<p>The macros in this section control how arguments are passed +on the stack. See the following section for other macros that +control passing certain arguments in registers. +</p> +<dl> +<dt><a name="index-TARGET_005fPROMOTE_005fPROTOTYPES"></a>Target Hook: <em>bool</em> <strong>TARGET_PROMOTE_PROTOTYPES</strong> <em>(const_tree <var>fntype</var>)</em></dt> +<dd><p>This target hook returns <code>true</code> if an argument declared in a +prototype as an integral type smaller than <code>int</code> should actually be +passed as an <code>int</code>. In addition to avoiding errors in certain +cases of mismatch, it also makes for better code on certain machines. +The default is to not promote prototypes. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fPUSH_005fARGUMENT"></a>Target Hook: <em>bool</em> <strong>TARGET_PUSH_ARGUMENT</strong> <em>(unsigned int <var>npush</var>)</em></dt> +<dd><p>This target hook returns <code>true</code> if push instructions will be +used to pass outgoing arguments. When the push instruction usage is +optional, <var>npush</var> is nonzero to indicate the number of bytes to +push. Otherwise, <var>npush</var> is zero. If the target machine does not +have a push instruction or push instruction should be avoided, +<code>false</code> should be returned. That directs GCC to use an alternate +strategy: to allocate the entire argument block and then store the +arguments into it. If this target hook may return <code>true</code>, +<code>PUSH_ROUNDING</code> must be defined. +</p></dd></dl> + +<dl> +<dt><a name="index-PUSH_005fARGS_005fREVERSED"></a>Macro: <strong>PUSH_ARGS_REVERSED</strong></dt> +<dd><p>A C expression. If nonzero, function arguments will be evaluated from +last to first, rather than from first to last. If this macro is not +defined, it defaults to <code>PUSH_ARGS</code> on targets where the stack +and args grow in opposite directions, and 0 otherwise. +</p></dd></dl> + +<dl> +<dt><a name="index-PUSH_005fROUNDING"></a>Macro: <strong>PUSH_ROUNDING</strong> <em>(<var>npushed</var>)</em></dt> +<dd><p>A C expression that is the number of bytes actually pushed onto the +stack when an instruction attempts to push <var>npushed</var> bytes. +</p> +<p>On some machines, the definition +</p> +<div class="smallexample"> +<pre class="smallexample">#define PUSH_ROUNDING(BYTES) (BYTES) +</pre></div> + +<p>will suffice. But on other machines, instructions that appear +to push one byte actually push two bytes in an attempt to maintain +alignment. Then the definition should be +</p> +<div class="smallexample"> +<pre class="smallexample">#define PUSH_ROUNDING(BYTES) (((BYTES) + 1) & ~1) +</pre></div> + +<p>If the value of this macro has a type, it should be an unsigned type. +</p></dd></dl> + +<a name="index-outgoing_005fargs_005fsize"></a> +<a name="index-crtl_002d_003eoutgoing_005fargs_005fsize"></a> +<dl> +<dt><a name="index-ACCUMULATE_005fOUTGOING_005fARGS"></a>Macro: <strong>ACCUMULATE_OUTGOING_ARGS</strong></dt> +<dd><p>A C expression. If nonzero, the maximum amount of space required for outgoing arguments +will be computed and placed into +<code>crtl->outgoing_args_size</code>. No space will be pushed +onto the stack for each call; instead, the function prologue should +increase the stack frame size by this amount. +</p> +<p>Setting both <code>PUSH_ARGS</code> and <code>ACCUMULATE_OUTGOING_ARGS</code> +is not proper. +</p></dd></dl> + +<dl> +<dt><a name="index-REG_005fPARM_005fSTACK_005fSPACE"></a>Macro: <strong>REG_PARM_STACK_SPACE</strong> <em>(<var>fndecl</var>)</em></dt> +<dd><p>Define this macro if functions should assume that stack space has been +allocated for arguments even when their values are passed in +registers. +</p> +<p>The value of this macro is the size, in bytes, of the area reserved for +arguments passed in registers for the function represented by <var>fndecl</var>, +which can be zero if GCC is calling a library function. +The argument <var>fndecl</var> can be the FUNCTION_DECL, or the type itself +of the function. +</p> +<p>This space can be allocated by the caller, or be a part of the +machine-dependent stack frame: <code>OUTGOING_REG_PARM_STACK_SPACE</code> says +which. +</p></dd></dl> + +<dl> +<dt><a name="index-INCOMING_005fREG_005fPARM_005fSTACK_005fSPACE"></a>Macro: <strong>INCOMING_REG_PARM_STACK_SPACE</strong> <em>(<var>fndecl</var>)</em></dt> +<dd><p>Like <code>REG_PARM_STACK_SPACE</code>, but for incoming register arguments. +Define this macro if space guaranteed when compiling a function body +is different to space required when making a call, a situation that +can arise with K&R style function definitions. +</p></dd></dl> + +<dl> +<dt><a name="index-OUTGOING_005fREG_005fPARM_005fSTACK_005fSPACE"></a>Macro: <strong>OUTGOING_REG_PARM_STACK_SPACE</strong> <em>(<var>fntype</var>)</em></dt> +<dd><p>Define this to a nonzero value if it is the responsibility of the +caller to allocate the area reserved for arguments passed in registers +when calling a function of <var>fntype</var>. <var>fntype</var> may be NULL +if the function called is a library function. +</p> +<p>If <code>ACCUMULATE_OUTGOING_ARGS</code> is defined, this macro controls +whether the space for these arguments counts in the value of +<code>crtl->outgoing_args_size</code>. +</p></dd></dl> + +<dl> +<dt><a name="index-STACK_005fPARMS_005fIN_005fREG_005fPARM_005fAREA"></a>Macro: <strong>STACK_PARMS_IN_REG_PARM_AREA</strong></dt> +<dd><p>Define this macro if <code>REG_PARM_STACK_SPACE</code> is defined, but the +stack parameters don’t skip the area specified by it. +</p> +<p>Normally, when a parameter is not passed in registers, it is placed on the +stack beyond the <code>REG_PARM_STACK_SPACE</code> area. Defining this macro +suppresses this behavior and causes the parameter to be passed on the +stack in its natural location. +</p></dd></dl> + +<dl> +<dt><a name="index-TARGET_005fRETURN_005fPOPS_005fARGS"></a>Target Hook: <em>poly_int64</em> <strong>TARGET_RETURN_POPS_ARGS</strong> <em>(tree <var>fundecl</var>, tree <var>funtype</var>, poly_int64 <var>size</var>)</em></dt> +<dd><p>This target hook returns the number of bytes of its own arguments that +a function pops on returning, or 0 if the function pops no arguments +and the caller must therefore pop them all after the function returns. +</p> +<p><var>fundecl</var> is a C variable whose value is a tree node that describes +the function in question. Normally it is a node of type +<code>FUNCTION_DECL</code> that describes the declaration of the function. +From this you can obtain the <code>DECL_ATTRIBUTES</code> of the function. +</p> +<p><var>funtype</var> is a C variable whose value is a tree node that +describes the function in question. Normally it is a node of type +<code>FUNCTION_TYPE</code> that describes the data type of the function. +From this it is possible to obtain the data types of the value and +arguments (if known). +</p> +<p>When a call to a library function is being considered, <var>fundecl</var> +will contain an identifier node for the library function. Thus, if +you need to distinguish among various library functions, you can do so +by their names. Note that “library function” in this context means +a function used to perform arithmetic, whose name is known specially +in the compiler and was not mentioned in the C code being compiled. +</p> +<p><var>size</var> is the number of bytes of arguments passed on the +stack. If a variable number of bytes is passed, it is zero, and +argument popping will always be the responsibility of the calling function. +</p> +<p>On the VAX, all functions always pop their arguments, so the definition +of this macro is <var>size</var>. On the 68000, using the standard +calling convention, no functions pop their arguments, so the value of +the macro is always 0 in this case. But an alternative calling +convention is available in which functions that take a fixed number of +arguments pop them but other functions (such as <code>printf</code>) pop +nothing (the caller pops all). When this convention is in use, +<var>funtype</var> is examined to determine whether a function takes a fixed +number of arguments. +</p></dd></dl> + +<dl> +<dt><a name="index-CALL_005fPOPS_005fARGS"></a>Macro: <strong>CALL_POPS_ARGS</strong> <em>(<var>cum</var>)</em></dt> +<dd><p>A C expression that should indicate the number of bytes a call sequence +pops off the stack. It is added to the value of <code>RETURN_POPS_ARGS</code> +when compiling a function call. +</p> +<p><var>cum</var> is the variable in which all arguments to the called function +have been accumulated. +</p> +<p>On certain architectures, such as the SH5, a call trampoline is used +that pops certain registers off the stack, depending on the arguments +that have been passed to the function. Since this is a property of the +call site, not of the called function, <code>RETURN_POPS_ARGS</code> is not +appropriate. +</p></dd></dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Register-Arguments.html#Register-Arguments" accesskey="n" rel="next">Register Arguments</a>, Previous: <a href="Elimination.html#Elimination" accesskey="p" rel="previous">Elimination</a>, Up: <a href="Stack-and-Calling.html#Stack-and-Calling" accesskey="u" rel="up">Stack and Calling</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |