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diff --git a/share/doc/gccint/Flags.html b/share/doc/gccint/Flags.html new file mode 100644 index 0000000..00d8acb --- /dev/null +++ b/share/doc/gccint/Flags.html @@ -0,0 +1,619 @@ +<!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). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. 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: Flags</title> + +<meta name="description" content="GNU Compiler Collection (GCC) Internals: Flags"> +<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Flags"> +<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="RTL.html#RTL" rel="up" title="RTL"> +<link href="Machine-Modes.html#Machine-Modes" rel="next" title="Machine Modes"> +<link href="Special-Accessors.html#Special-Accessors" rel="previous" title="Special Accessors"> +<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="Flags"></a> +<div class="header"> +<p> +Next: <a href="Machine-Modes.html#Machine-Modes" accesskey="n" rel="next">Machine Modes</a>, Previous: <a href="Special-Accessors.html#Special-Accessors" accesskey="p" rel="previous">Special Accessors</a>, Up: <a href="RTL.html#RTL" accesskey="u" rel="up">RTL</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="Flags-in-an-RTL-Expression"></a> +<h3 class="section">14.5 Flags in an RTL Expression</h3> +<a name="index-flags-in-RTL-expression"></a> + +<p>RTL expressions contain several flags (one-bit bit-fields) +that are used in certain types of expression. Most often they +are accessed with the following macros, which expand into lvalues. +</p> +<dl compact="compact"> +<dd><a name="index-CROSSING_005fJUMP_005fP"></a> +<a name="index-jump_005finsn-and-_002fj"></a> +</dd> +<dt><code>CROSSING_JUMP_P (<var>x</var>)</code></dt> +<dd><p>Nonzero in a <code>jump_insn</code> if it crosses between hot and cold sections, +which could potentially be very far apart in the executable. The presence +of this flag indicates to other optimizations that this branching instruction +should not be “collapsed” into a simpler branching construct. It is used +when the optimization to partition basic blocks into hot and cold sections +is turned on. +</p> +<a name="index-CONSTANT_005fPOOL_005fADDRESS_005fP"></a> +<a name="index-symbol_005fref-and-_002fu"></a> +<a name="index-unchanging_002c-in-symbol_005fref"></a> +</dd> +<dt><code>CONSTANT_POOL_ADDRESS_P (<var>x</var>)</code></dt> +<dd><p>Nonzero in a <code>symbol_ref</code> if it refers to part of the current +function’s constant pool. For most targets these addresses are in a +<code>.rodata</code> section entirely separate from the function, but for +some targets the addresses are close to the beginning of the function. +In either case GCC assumes these addresses can be addressed directly, +perhaps with the help of base registers. +Stored in the <code>unchanging</code> field and printed as ‘<samp>/u</samp>’. +</p> +<a name="index-INSN_005fANNULLED_005fBRANCH_005fP"></a> +<a name="index-jump_005finsn-and-_002fu"></a> +<a name="index-call_005finsn-and-_002fu"></a> +<a name="index-insn-and-_002fu"></a> +<a name="index-unchanging_002c-in-jump_005finsn_002c-call_005finsn-and-insn"></a> +</dd> +<dt><code>INSN_ANNULLED_BRANCH_P (<var>x</var>)</code></dt> +<dd><p>In a <code>jump_insn</code>, <code>call_insn</code>, or <code>insn</code> indicates +that the branch is an annulling one. See the discussion under +<code>sequence</code> below. Stored in the <code>unchanging</code> field and +printed as ‘<samp>/u</samp>’. +</p> +<a name="index-INSN_005fDELETED_005fP"></a> +<a name="index-insn-and-_002fv"></a> +<a name="index-call_005finsn-and-_002fv"></a> +<a name="index-jump_005finsn-and-_002fv"></a> +<a name="index-code_005flabel-and-_002fv"></a> +<a name="index-jump_005ftable_005fdata-and-_002fv"></a> +<a name="index-barrier-and-_002fv"></a> +<a name="index-note-and-_002fv"></a> +<a name="index-volatil_002c-in-insn_002c-call_005finsn_002c-jump_005finsn_002c-code_005flabel_002c-jump_005ftable_005fdata_002c-barrier_002c-and-note"></a> +</dd> +<dt><code>INSN_DELETED_P (<var>x</var>)</code></dt> +<dd><p>In an <code>insn</code>, <code>call_insn</code>, <code>jump_insn</code>, <code>code_label</code>, +<code>jump_table_data</code>, <code>barrier</code>, or <code>note</code>, +nonzero if the insn has been deleted. Stored in the +<code>volatil</code> field and printed as ‘<samp>/v</samp>’. +</p> +<a name="index-INSN_005fFROM_005fTARGET_005fP"></a> +<a name="index-insn-and-_002fs"></a> +<a name="index-jump_005finsn-and-_002fs"></a> +<a name="index-call_005finsn-and-_002fs"></a> +<a name="index-in_005fstruct_002c-in-insn-and-jump_005finsn-and-call_005finsn"></a> +</dd> +<dt><code>INSN_FROM_TARGET_P (<var>x</var>)</code></dt> +<dd><p>In an <code>insn</code> or <code>jump_insn</code> or <code>call_insn</code> in a delay +slot of a branch, indicates that the insn +is from the target of the branch. If the branch insn has +<code>INSN_ANNULLED_BRANCH_P</code> set, this insn will only be executed if +the branch is taken. For annulled branches with +<code>INSN_FROM_TARGET_P</code> clear, the insn will be executed only if the +branch is not taken. When <code>INSN_ANNULLED_BRANCH_P</code> is not set, +this insn will always be executed. Stored in the <code>in_struct</code> +field and printed as ‘<samp>/s</samp>’. +</p> +<a name="index-LABEL_005fPRESERVE_005fP"></a> +<a name="index-code_005flabel-and-_002fi"></a> +<a name="index-note-and-_002fi"></a> +<a name="index-in_005fstruct_002c-in-code_005flabel-and-note"></a> +</dd> +<dt><code>LABEL_PRESERVE_P (<var>x</var>)</code></dt> +<dd><p>In a <code>code_label</code> or <code>note</code>, indicates that the label is referenced by +code or data not visible to the RTL of a given function. +Labels referenced by a non-local goto will have this bit set. Stored +in the <code>in_struct</code> field and printed as ‘<samp>/s</samp>’. +</p> +<a name="index-LABEL_005fREF_005fNONLOCAL_005fP"></a> +<a name="index-label_005fref-and-_002fv"></a> +<a name="index-reg_005flabel-and-_002fv"></a> +<a name="index-volatil_002c-in-label_005fref-and-reg_005flabel"></a> +</dd> +<dt><code>LABEL_REF_NONLOCAL_P (<var>x</var>)</code></dt> +<dd><p>In <code>label_ref</code> and <code>reg_label</code> expressions, nonzero if this is +a reference to a non-local label. +Stored in the <code>volatil</code> field and printed as ‘<samp>/v</samp>’. +</p> +<a name="index-MEM_005fKEEP_005fALIAS_005fSET_005fP"></a> +<a name="index-mem-and-_002fj"></a> +<a name="index-jump_002c-in-mem"></a> +</dd> +<dt><code>MEM_KEEP_ALIAS_SET_P (<var>x</var>)</code></dt> +<dd><p>In <code>mem</code> expressions, 1 if we should keep the alias set for this +mem unchanged when we access a component. Set to 1, for example, when we +are already in a non-addressable component of an aggregate. +Stored in the <code>jump</code> field and printed as ‘<samp>/j</samp>’. +</p> +<a name="index-MEM_005fVOLATILE_005fP"></a> +<a name="index-mem-and-_002fv"></a> +<a name="index-asm_005finput-and-_002fv"></a> +<a name="index-asm_005foperands-and-_002fv"></a> +<a name="index-volatil_002c-in-mem_002c-asm_005foperands_002c-and-asm_005finput"></a> +</dd> +<dt><code>MEM_VOLATILE_P (<var>x</var>)</code></dt> +<dd><p>In <code>mem</code>, <code>asm_operands</code>, and <code>asm_input</code> expressions, +nonzero for volatile memory references. +Stored in the <code>volatil</code> field and printed as ‘<samp>/v</samp>’. +</p> +<a name="index-MEM_005fNOTRAP_005fP"></a> +<a name="index-mem-and-_002fc"></a> +<a name="index-call_002c-in-mem"></a> +</dd> +<dt><code>MEM_NOTRAP_P (<var>x</var>)</code></dt> +<dd><p>In <code>mem</code>, nonzero for memory references that will not trap. +Stored in the <code>call</code> field and printed as ‘<samp>/c</samp>’. +</p> +<a name="index-MEM_005fPOINTER"></a> +<a name="index-mem-and-_002ff"></a> +<a name="index-frame_005frelated_002c-in-mem"></a> +</dd> +<dt><code>MEM_POINTER (<var>x</var>)</code></dt> +<dd><p>Nonzero in a <code>mem</code> if the memory reference holds a pointer. +Stored in the <code>frame_related</code> field and printed as ‘<samp>/f</samp>’. +</p> +<a name="index-MEM_005fREADONLY_005fP"></a> +<a name="index-mem-and-_002fu"></a> +<a name="index-unchanging_002c-in-mem"></a> +</dd> +<dt><code>MEM_READONLY_P (<var>x</var>)</code></dt> +<dd><p>Nonzero in a <code>mem</code>, if the memory is statically allocated and read-only. +</p> +<p>Read-only in this context means never modified during the lifetime of the +program, not necessarily in ROM or in write-disabled pages. A common +example of the later is a shared library’s global offset table. This +table is initialized by the runtime loader, so the memory is technically +writable, but after control is transferred from the runtime loader to the +application, this memory will never be subsequently modified. +</p> +<p>Stored in the <code>unchanging</code> field and printed as ‘<samp>/u</samp>’. +</p> +<a name="index-PREFETCH_005fSCHEDULE_005fBARRIER_005fP"></a> +<a name="index-prefetch-and-_002fv"></a> +<a name="index-volatile_002c-in-prefetch"></a> +</dd> +<dt><code>PREFETCH_SCHEDULE_BARRIER_P (<var>x</var>)</code></dt> +<dd><p>In a <code>prefetch</code>, indicates that the prefetch is a scheduling barrier. +No other INSNs will be moved over it. +Stored in the <code>volatil</code> field and printed as ‘<samp>/v</samp>’. +</p> +<a name="index-REG_005fFUNCTION_005fVALUE_005fP"></a> +<a name="index-reg-and-_002fi"></a> +<a name="index-return_005fval_002c-in-reg"></a> +</dd> +<dt><code>REG_FUNCTION_VALUE_P (<var>x</var>)</code></dt> +<dd><p>Nonzero in a <code>reg</code> if it is the place in which this function’s +value is going to be returned. (This happens only in a hard +register.) Stored in the <code>return_val</code> field and printed as +‘<samp>/i</samp>’. +</p> +<a name="index-REG_005fPOINTER"></a> +<a name="index-reg-and-_002ff"></a> +<a name="index-frame_005frelated_002c-in-reg"></a> +</dd> +<dt><code>REG_POINTER (<var>x</var>)</code></dt> +<dd><p>Nonzero in a <code>reg</code> if the register holds a pointer. Stored in the +<code>frame_related</code> field and printed as ‘<samp>/f</samp>’. +</p> +<a name="index-REG_005fUSERVAR_005fP"></a> +<a name="index-reg-and-_002fv"></a> +<a name="index-volatil_002c-in-reg"></a> +</dd> +<dt><code>REG_USERVAR_P (<var>x</var>)</code></dt> +<dd><p>In a <code>reg</code>, nonzero if it corresponds to a variable present in +the user’s source code. Zero for temporaries generated internally by +the compiler. Stored in the <code>volatil</code> field and printed as +‘<samp>/v</samp>’. +</p> +<p>The same hard register may be used also for collecting the values of +functions called by this one, but <code>REG_FUNCTION_VALUE_P</code> is zero +in this kind of use. +</p> +<a name="index-RTL_005fCONST_005fCALL_005fP"></a> +<a name="index-call_005finsn-and-_002fu-1"></a> +<a name="index-unchanging_002c-in-call_005finsn"></a> +</dd> +<dt><code>RTL_CONST_CALL_P (<var>x</var>)</code></dt> +<dd><p>In a <code>call_insn</code> indicates that the insn represents a call to a +const function. Stored in the <code>unchanging</code> field and printed as +‘<samp>/u</samp>’. +</p> +<a name="index-RTL_005fPURE_005fCALL_005fP"></a> +<a name="index-call_005finsn-and-_002fi"></a> +<a name="index-return_005fval_002c-in-call_005finsn"></a> +</dd> +<dt><code>RTL_PURE_CALL_P (<var>x</var>)</code></dt> +<dd><p>In a <code>call_insn</code> indicates that the insn represents a call to a +pure function. Stored in the <code>return_val</code> field and printed as +‘<samp>/i</samp>’. +</p> +<a name="index-RTL_005fCONST_005fOR_005fPURE_005fCALL_005fP"></a> +<a name="index-call_005finsn-and-_002fu-or-_002fi"></a> +</dd> +<dt><code>RTL_CONST_OR_PURE_CALL_P (<var>x</var>)</code></dt> +<dd><p>In a <code>call_insn</code>, true if <code>RTL_CONST_CALL_P</code> or +<code>RTL_PURE_CALL_P</code> is true. +</p> +<a name="index-RTL_005fLOOPING_005fCONST_005fOR_005fPURE_005fCALL_005fP"></a> +<a name="index-call_005finsn-and-_002fc"></a> +<a name="index-call_002c-in-call_005finsn"></a> +</dd> +<dt><code>RTL_LOOPING_CONST_OR_PURE_CALL_P (<var>x</var>)</code></dt> +<dd><p>In a <code>call_insn</code> indicates that the insn represents a possibly +infinite looping call to a const or pure function. Stored in the +<code>call</code> field and printed as ‘<samp>/c</samp>’. Only true if one of +<code>RTL_CONST_CALL_P</code> or <code>RTL_PURE_CALL_P</code> is true. +</p> +<a name="index-RTX_005fFRAME_005fRELATED_005fP"></a> +<a name="index-insn-and-_002ff"></a> +<a name="index-call_005finsn-and-_002ff"></a> +<a name="index-jump_005finsn-and-_002ff"></a> +<a name="index-barrier-and-_002ff"></a> +<a name="index-set-and-_002ff"></a> +<a name="index-frame_005frelated_002c-in-insn_002c-call_005finsn_002c-jump_005finsn_002c-barrier_002c-and-set"></a> +</dd> +<dt><code>RTX_FRAME_RELATED_P (<var>x</var>)</code></dt> +<dd><p>Nonzero in an <code>insn</code>, <code>call_insn</code>, <code>jump_insn</code>, +<code>barrier</code>, or <code>set</code> which is part of a function prologue +and sets the stack pointer, sets the frame pointer, or saves a register. +This flag should also be set on an instruction that sets up a temporary +register to use in place of the frame pointer. +Stored in the <code>frame_related</code> field and printed as ‘<samp>/f</samp>’. +</p> +<p>In particular, on RISC targets where there are limits on the sizes of +immediate constants, it is sometimes impossible to reach the register +save area directly from the stack pointer. In that case, a temporary +register is used that is near enough to the register save area, and the +Canonical Frame Address, i.e., DWARF2’s logical frame pointer, register +must (temporarily) be changed to be this temporary register. So, the +instruction that sets this temporary register must be marked as +<code>RTX_FRAME_RELATED_P</code>. +</p> +<p>If the marked instruction is overly complex (defined in terms of what +<code>dwarf2out_frame_debug_expr</code> can handle), you will also have to +create a <code>REG_FRAME_RELATED_EXPR</code> note and attach it to the +instruction. This note should contain a simple expression of the +computation performed by this instruction, i.e., one that +<code>dwarf2out_frame_debug_expr</code> can handle. +</p> +<p>This flag is required for exception handling support on targets with RTL +prologues. +</p> +<a name="index-SCHED_005fGROUP_005fP"></a> +<a name="index-insn-and-_002fs-1"></a> +<a name="index-call_005finsn-and-_002fs-1"></a> +<a name="index-jump_005finsn-and-_002fs-1"></a> +<a name="index-jump_005ftable_005fdata-and-_002fs"></a> +<a name="index-in_005fstruct_002c-in-insn_002c-call_005finsn_002c-jump_005finsn-and-jump_005ftable_005fdata"></a> +</dd> +<dt><code>SCHED_GROUP_P (<var>x</var>)</code></dt> +<dd><p>During instruction scheduling, in an <code>insn</code>, <code>call_insn</code>, +<code>jump_insn</code> or <code>jump_table_data</code>, indicates that the +previous insn must be scheduled together with this insn. This is used to +ensure that certain groups of instructions will not be split up by the +instruction scheduling pass, for example, <code>use</code> insns before +a <code>call_insn</code> may not be separated from the <code>call_insn</code>. +Stored in the <code>in_struct</code> field and printed as ‘<samp>/s</samp>’. +</p> +<a name="index-SET_005fIS_005fRETURN_005fP"></a> +<a name="index-insn-and-_002fj"></a> +<a name="index-jump_002c-in-insn"></a> +</dd> +<dt><code>SET_IS_RETURN_P (<var>x</var>)</code></dt> +<dd><p>For a <code>set</code>, nonzero if it is for a return. +Stored in the <code>jump</code> field and printed as ‘<samp>/j</samp>’. +</p> +<a name="index-SIBLING_005fCALL_005fP"></a> +<a name="index-call_005finsn-and-_002fj"></a> +<a name="index-jump_002c-in-call_005finsn"></a> +</dd> +<dt><code>SIBLING_CALL_P (<var>x</var>)</code></dt> +<dd><p>For a <code>call_insn</code>, nonzero if the insn is a sibling call. +Stored in the <code>jump</code> field and printed as ‘<samp>/j</samp>’. +</p> +<a name="index-STRING_005fPOOL_005fADDRESS_005fP"></a> +<a name="index-symbol_005fref-and-_002ff"></a> +<a name="index-frame_005frelated_002c-in-symbol_005fref"></a> +</dd> +<dt><code>STRING_POOL_ADDRESS_P (<var>x</var>)</code></dt> +<dd><p>For a <code>symbol_ref</code> expression, nonzero if it addresses this function’s +string constant pool. +Stored in the <code>frame_related</code> field and printed as ‘<samp>/f</samp>’. +</p> +<a name="index-SUBREG_005fPROMOTED_005fUNSIGNED_005fP"></a> +<a name="index-subreg-and-_002fu-and-_002fv"></a> +<a name="index-unchanging_002c-in-subreg"></a> +<a name="index-volatil_002c-in-subreg"></a> +</dd> +<dt><code>SUBREG_PROMOTED_UNSIGNED_P (<var>x</var>)</code></dt> +<dd><p>Returns a value greater then zero for a <code>subreg</code> that has +<code>SUBREG_PROMOTED_VAR_P</code> nonzero if the object being referenced is kept +zero-extended, zero if it is kept sign-extended, and less then zero if it is +extended some other way via the <code>ptr_extend</code> instruction. +Stored in the <code>unchanging</code> +field and <code>volatil</code> field, printed as ‘<samp>/u</samp>’ and ‘<samp>/v</samp>’. +This macro may only be used to get the value it may not be used to change +the value. Use <code>SUBREG_PROMOTED_UNSIGNED_SET</code> to change the value. +</p> +<a name="index-SUBREG_005fPROMOTED_005fUNSIGNED_005fSET"></a> +<a name="index-subreg-and-_002fu"></a> +<a name="index-unchanging_002c-in-subreg-1"></a> +<a name="index-volatil_002c-in-subreg-1"></a> +</dd> +<dt><code>SUBREG_PROMOTED_UNSIGNED_SET (<var>x</var>)</code></dt> +<dd><p>Set the <code>unchanging</code> and <code>volatil</code> fields in a <code>subreg</code> +to reflect zero, sign, or other extension. If <code>volatil</code> is +zero, then <code>unchanging</code> as nonzero means zero extension and as +zero means sign extension. If <code>volatil</code> is nonzero then some +other type of extension was done via the <code>ptr_extend</code> instruction. +</p> +<a name="index-SUBREG_005fPROMOTED_005fVAR_005fP"></a> +<a name="index-subreg-and-_002fs"></a> +<a name="index-in_005fstruct_002c-in-subreg"></a> +</dd> +<dt><code>SUBREG_PROMOTED_VAR_P (<var>x</var>)</code></dt> +<dd><p>Nonzero in a <code>subreg</code> if it was made when accessing an object that +was promoted to a wider mode in accord with the <code>PROMOTED_MODE</code> machine +description macro (see <a href="Storage-Layout.html#Storage-Layout">Storage Layout</a>). In this case, the mode of +the <code>subreg</code> is the declared mode of the object and the mode of +<code>SUBREG_REG</code> is the mode of the register that holds the object. +Promoted variables are always either sign- or zero-extended to the wider +mode on every assignment. Stored in the <code>in_struct</code> field and +printed as ‘<samp>/s</samp>’. +</p> +<a name="index-SYMBOL_005fREF_005fUSED"></a> +<a name="index-used_002c-in-symbol_005fref"></a> +</dd> +<dt><code>SYMBOL_REF_USED (<var>x</var>)</code></dt> +<dd><p>In a <code>symbol_ref</code>, indicates that <var>x</var> has been used. This is +normally only used to ensure that <var>x</var> is only declared external +once. Stored in the <code>used</code> field. +</p> +<a name="index-SYMBOL_005fREF_005fWEAK"></a> +<a name="index-symbol_005fref-and-_002fi"></a> +<a name="index-return_005fval_002c-in-symbol_005fref"></a> +</dd> +<dt><code>SYMBOL_REF_WEAK (<var>x</var>)</code></dt> +<dd><p>In a <code>symbol_ref</code>, indicates that <var>x</var> has been declared weak. +Stored in the <code>return_val</code> field and printed as ‘<samp>/i</samp>’. +</p> +<a name="index-SYMBOL_005fREF_005fFLAG"></a> +<a name="index-symbol_005fref-and-_002fv"></a> +<a name="index-volatil_002c-in-symbol_005fref"></a> +</dd> +<dt><code>SYMBOL_REF_FLAG (<var>x</var>)</code></dt> +<dd><p>In a <code>symbol_ref</code>, this is used as a flag for machine-specific purposes. +Stored in the <code>volatil</code> field and printed as ‘<samp>/v</samp>’. +</p> +<p>Most uses of <code>SYMBOL_REF_FLAG</code> are historic and may be subsumed +by <code>SYMBOL_REF_FLAGS</code>. Certainly use of <code>SYMBOL_REF_FLAGS</code> +is mandatory if the target requires more than one bit of storage. +</p></dd> +</dl> + +<p>These are the fields to which the above macros refer: +</p> +<dl compact="compact"> +<dd><a name="index-call"></a> +<a name="index-_002fc-in-RTL-dump"></a> +</dd> +<dt><code>call</code></dt> +<dd><p>In a <code>mem</code>, 1 means that the memory reference will not trap. +</p> +<p>In a <code>call</code>, 1 means that this pure or const call may possibly +infinite loop. +</p> +<p>In an RTL dump, this flag is represented as ‘<samp>/c</samp>’. +</p> +<a name="index-frame_005frelated"></a> +<a name="index-_002ff-in-RTL-dump"></a> +</dd> +<dt><code>frame_related</code></dt> +<dd><p>In an <code>insn</code> or <code>set</code> expression, 1 means that it is part of +a function prologue and sets the stack pointer, sets the frame pointer, +saves a register, or sets up a temporary register to use in place of the +frame pointer. +</p> +<p>In <code>reg</code> expressions, 1 means that the register holds a pointer. +</p> +<p>In <code>mem</code> expressions, 1 means that the memory reference holds a pointer. +</p> +<p>In <code>symbol_ref</code> expressions, 1 means that the reference addresses +this function’s string constant pool. +</p> +<p>In an RTL dump, this flag is represented as ‘<samp>/f</samp>’. +</p> +<a name="index-in_005fstruct"></a> +<a name="index-_002fs-in-RTL-dump"></a> +</dd> +<dt><code>in_struct</code></dt> +<dd><p>In <code>reg</code> expressions, it is 1 if the register has its entire life +contained within the test expression of some loop. +</p> +<p>In <code>subreg</code> expressions, 1 means that the <code>subreg</code> is accessing +an object that has had its mode promoted from a wider mode. +</p> +<p>In <code>label_ref</code> expressions, 1 means that the referenced label is +outside the innermost loop containing the insn in which the <code>label_ref</code> +was found. +</p> +<p>In <code>code_label</code> expressions, it is 1 if the label may never be deleted. +This is used for labels which are the target of non-local gotos. Such a +label that would have been deleted is replaced with a <code>note</code> of type +<code>NOTE_INSN_DELETED_LABEL</code>. +</p> +<p>In an <code>insn</code> during dead-code elimination, 1 means that the insn is +dead code. +</p> +<p>In an <code>insn</code> or <code>jump_insn</code> during reorg for an insn in the +delay slot of a branch, +1 means that this insn is from the target of the branch. +</p> +<p>In an <code>insn</code> during instruction scheduling, 1 means that this insn +must be scheduled as part of a group together with the previous insn. +</p> +<p>In an RTL dump, this flag is represented as ‘<samp>/s</samp>’. +</p> +<a name="index-return_005fval"></a> +<a name="index-_002fi-in-RTL-dump"></a> +</dd> +<dt><code>return_val</code></dt> +<dd><p>In <code>reg</code> expressions, 1 means the register contains +the value to be returned by the current function. On +machines that pass parameters in registers, the same register number +may be used for parameters as well, but this flag is not set on such +uses. +</p> +<p>In <code>symbol_ref</code> expressions, 1 means the referenced symbol is weak. +</p> +<p>In <code>call</code> expressions, 1 means the call is pure. +</p> +<p>In an RTL dump, this flag is represented as ‘<samp>/i</samp>’. +</p> +<a name="index-jump"></a> +<a name="index-_002fj-in-RTL-dump"></a> +</dd> +<dt><code>jump</code></dt> +<dd><p>In a <code>mem</code> expression, 1 means we should keep the alias set for this +mem unchanged when we access a component. +</p> +<p>In a <code>set</code>, 1 means it is for a return. +</p> +<p>In a <code>call_insn</code>, 1 means it is a sibling call. +</p> +<p>In a <code>jump_insn</code>, 1 means it is a crossing jump. +</p> +<p>In an RTL dump, this flag is represented as ‘<samp>/j</samp>’. +</p> +<a name="index-unchanging"></a> +<a name="index-_002fu-in-RTL-dump"></a> +</dd> +<dt><code>unchanging</code></dt> +<dd><p>In <code>reg</code> and <code>mem</code> expressions, 1 means +that the value of the expression never changes. +</p> +<p>In <code>subreg</code> expressions, it is 1 if the <code>subreg</code> references an +unsigned object whose mode has been promoted to a wider mode. +</p> +<p>In an <code>insn</code> or <code>jump_insn</code> in the delay slot of a branch +instruction, 1 means an annulling branch should be used. +</p> +<p>In a <code>symbol_ref</code> expression, 1 means that this symbol addresses +something in the per-function constant pool. +</p> +<p>In a <code>call_insn</code> 1 means that this instruction is a call to a const +function. +</p> +<p>In an RTL dump, this flag is represented as ‘<samp>/u</samp>’. +</p> +<a name="index-used"></a> +</dd> +<dt><code>used</code></dt> +<dd><p>This flag is used directly (without an access macro) at the end of RTL +generation for a function, to count the number of times an expression +appears in insns. Expressions that appear more than once are copied, +according to the rules for shared structure (see <a href="Sharing.html#Sharing">Sharing</a>). +</p> +<p>For a <code>reg</code>, it is used directly (without an access macro) by the +leaf register renumbering code to ensure that each register is only +renumbered once. +</p> +<p>In a <code>symbol_ref</code>, it indicates that an external declaration for +the symbol has already been written. +</p> +<a name="index-volatil"></a> +<a name="index-_002fv-in-RTL-dump"></a> +<a name="index-volatile-memory-references"></a> +</dd> +<dt><code>volatil</code></dt> +<dd><p>In a <code>mem</code>, <code>asm_operands</code>, or <code>asm_input</code> +expression, it is 1 if the memory +reference is volatile. Volatile memory references may not be deleted, +reordered or combined. +</p> +<p>In a <code>symbol_ref</code> expression, it is used for machine-specific +purposes. +</p> +<p>In a <code>reg</code> expression, it is 1 if the value is a user-level variable. +0 indicates an internal compiler temporary. +</p> +<p>In an <code>insn</code>, 1 means the insn has been deleted. +</p> +<p>In <code>label_ref</code> and <code>reg_label</code> expressions, 1 means a reference +to a non-local label. +</p> +<p>In <code>prefetch</code> expressions, 1 means that the containing insn is a +scheduling barrier. +</p> +<p>In an RTL dump, this flag is represented as ‘<samp>/v</samp>’. +</p></dd> +</dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Machine-Modes.html#Machine-Modes" accesskey="n" rel="next">Machine Modes</a>, Previous: <a href="Special-Accessors.html#Special-Accessors" accesskey="p" rel="previous">Special Accessors</a>, Up: <a href="RTL.html#RTL" accesskey="u" rel="up">RTL</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> |