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376 lines
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HTML
4 years ago
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<html lang="en">
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<title>Flags - GNU Compiler Collection (GCC) Internals</title>
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<meta name="description" content="GNU Compiler Collection (GCC) Internals">
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<link rel="up" href="RTL.html#RTL" title="RTL">
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<link rel="prev" href="Special-Accessors.html#Special-Accessors" title="Special Accessors">
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<link rel="next" href="Machine-Modes.html#Machine-Modes" title="Machine Modes">
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Copyright (C) 1988-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being ``Funding Free Software'', the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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``GNU Free Documentation License''.
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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</head>
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<body>
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<div class="node">
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<a name="Flags"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Machine-Modes.html#Machine-Modes">Machine Modes</a>,
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Previous: <a rel="previous" accesskey="p" href="Special-Accessors.html#Special-Accessors">Special Accessors</a>,
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Up: <a rel="up" accesskey="u" href="RTL.html#RTL">RTL</a>
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<hr>
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</div>
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<h3 class="section">13.5 Flags in an RTL Expression</h3>
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<p><a name="index-flags-in-RTL-expression-2600"></a>
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RTL expressions contain several flags (one-bit bit-fields)
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that are used in certain types of expression. Most often they
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are accessed with the following macros, which expand into lvalues.
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<a name="index-CONSTANT_005fPOOL_005fADDRESS_005fP-2601"></a>
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<a name="index-g_t_0040code_007bsymbol_005fref_007d-and-_0040samp_007b_002fu_007d-2602"></a>
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<a name="index-g_t_0040code_007bunchanging_007d_002c-in-_0040code_007bsymbol_005fref_007d-2603"></a>
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<dl><dt><code>CONSTANT_POOL_ADDRESS_P (</code><var>x</var><code>)</code><dd>Nonzero in a <code>symbol_ref</code> if it refers to part of the current
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function's constant pool. For most targets these addresses are in a
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<code>.rodata</code> section entirely separate from the function, but for
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some targets the addresses are close to the beginning of the function.
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In either case GCC assumes these addresses can be addressed directly,
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perhaps with the help of base registers.
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Stored in the <code>unchanging</code> field and printed as ‘<samp><span class="samp">/u</span></samp>’.
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<p><a name="index-RTL_005fCONST_005fCALL_005fP-2604"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002fu_007d-2605"></a><a name="index-g_t_0040code_007bunchanging_007d_002c-in-_0040code_007bcall_005finsn_007d-2606"></a><br><dt><code>RTL_CONST_CALL_P (</code><var>x</var><code>)</code><dd>In a <code>call_insn</code> indicates that the insn represents a call to a
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const function. Stored in the <code>unchanging</code> field and printed as
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‘<samp><span class="samp">/u</span></samp>’.
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<p><a name="index-RTL_005fPURE_005fCALL_005fP-2607"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002fi_007d-2608"></a><a name="index-g_t_0040code_007breturn_005fval_007d_002c-in-_0040code_007bcall_005finsn_007d-2609"></a><br><dt><code>RTL_PURE_CALL_P (</code><var>x</var><code>)</code><dd>In a <code>call_insn</code> indicates that the insn represents a call to a
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pure function. Stored in the <code>return_val</code> field and printed as
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‘<samp><span class="samp">/i</span></samp>’.
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<p><a name="index-RTL_005fCONST_005fOR_005fPURE_005fCALL_005fP-2610"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002fu_007d-or-_0040samp_007b_002fi_007d-2611"></a><br><dt><code>RTL_CONST_OR_PURE_CALL_P (</code><var>x</var><code>)</code><dd>In a <code>call_insn</code>, true if <code>RTL_CONST_CALL_P</code> or
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<code>RTL_PURE_CALL_P</code> is true.
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<p><a name="index-RTL_005fLOOPING_005fCONST_005fOR_005fPURE_005fCALL_005fP-2612"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002fc_007d-2613"></a><a name="index-g_t_0040code_007bcall_007d_002c-in-_0040code_007bcall_005finsn_007d-2614"></a><br><dt><code>RTL_LOOPING_CONST_OR_PURE_CALL_P (</code><var>x</var><code>)</code><dd>In a <code>call_insn</code> indicates that the insn represents a possibly
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infinite looping call to a const or pure function. Stored in the
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<code>call</code> field and printed as ‘<samp><span class="samp">/c</span></samp>’. Only true if one of
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<code>RTL_CONST_CALL_P</code> or <code>RTL_PURE_CALL_P</code> is true.
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<p><a name="index-INSN_005fANNULLED_005fBRANCH_005fP-2615"></a><a name="index-g_t_0040code_007bjump_005finsn_007d-and-_0040samp_007b_002fu_007d-2616"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002fu_007d-2617"></a><a name="index-g_t_0040code_007binsn_007d-and-_0040samp_007b_002fu_007d-2618"></a><a name="index-g_t_0040code_007bunchanging_007d_002c-in-_0040code_007bjump_005finsn_007d_002c-_0040code_007bcall_005finsn_007d-and-_0040code_007binsn_007d-2619"></a><br><dt><code>INSN_ANNULLED_BRANCH_P (</code><var>x</var><code>)</code><dd>In a <code>jump_insn</code>, <code>call_insn</code>, or <code>insn</code> indicates
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that the branch is an annulling one. See the discussion under
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<code>sequence</code> below. Stored in the <code>unchanging</code> field and
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printed as ‘<samp><span class="samp">/u</span></samp>’.
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<p><a name="index-INSN_005fDELETED_005fP-2620"></a><a name="index-g_t_0040code_007binsn_007d-and-_0040samp_007b_002fv_007d-2621"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002fv_007d-2622"></a><a name="index-g_t_0040code_007bjump_005finsn_007d-and-_0040samp_007b_002fv_007d-2623"></a><a name="index-g_t_0040code_007bcode_005flabel_007d-and-_0040samp_007b_002fv_007d-2624"></a><a name="index-g_t_0040code_007bjump_005ftable_005fdata_007d-and-_0040samp_007b_002fv_007d-2625"></a><a name="index-g_t_0040code_007bbarrier_007d-and-_0040samp_007b_002fv_007d-2626"></a><a name="index-g_t_0040code_007bnote_007d-and-_0040samp_007b_002fv_007d-2627"></a><a name="index-g_t_0040code_007bvolatil_007d_002c-in-_0040code_007binsn_007d_002c-_0040code_007bcall_005finsn_007d_002c-_0040code_007bjump_005finsn_007d_002c-_0040code_007bcode_005flabel_007d_002c-_0040code_007bjump_005ftable_005fdata_007d_002c-_0040code_007bbarrier_007d_002c-and-_0040code_007bnote_007d-2628"></a><br><dt><code>INSN_DELETED_P (</code><var>x</var><code>)</code><dd>In an <code>insn</code>, <code>call_insn</code>, <code>jump_insn</code>, <code>code_label</code>,
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<code>jump_table_data</code>, <code>barrier</code>, or <code>note</code>,
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nonzero if the insn has been deleted. Stored in the
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<code>volatil</code> field and printed as ‘<samp><span class="samp">/v</span></samp>’.
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<p><a name="index-INSN_005fFROM_005fTARGET_005fP-2629"></a><a name="index-g_t_0040code_007binsn_007d-and-_0040samp_007b_002fs_007d-2630"></a><a name="index-g_t_0040code_007bjump_005finsn_007d-and-_0040samp_007b_002fs_007d-2631"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002fs_007d-2632"></a><a name="index-g_t_0040code_007bin_005fstruct_007d_002c-in-_0040code_007binsn_007d-and-_0040code_007bjump_005finsn_007d-and-_0040code_007bcall_005finsn_007d-2633"></a><br><dt><code>INSN_FROM_TARGET_P (</code><var>x</var><code>)</code><dd>In an <code>insn</code> or <code>jump_insn</code> or <code>call_insn</code> in a delay
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slot of a branch, indicates that the insn
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is from the target of the branch. If the branch insn has
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<code>INSN_ANNULLED_BRANCH_P</code> set, this insn will only be executed if
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the branch is taken. For annulled branches with
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<code>INSN_FROM_TARGET_P</code> clear, the insn will be executed only if the
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branch is not taken. When <code>INSN_ANNULLED_BRANCH_P</code> is not set,
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this insn will always be executed. Stored in the <code>in_struct</code>
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field and printed as ‘<samp><span class="samp">/s</span></samp>’.
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<p><a name="index-LABEL_005fPRESERVE_005fP-2634"></a><a name="index-g_t_0040code_007bcode_005flabel_007d-and-_0040samp_007b_002fi_007d-2635"></a><a name="index-g_t_0040code_007bnote_007d-and-_0040samp_007b_002fi_007d-2636"></a><a name="index-g_t_0040code_007bin_005fstruct_007d_002c-in-_0040code_007bcode_005flabel_007d-and-_0040code_007bnote_007d-2637"></a><br><dt><code>LABEL_PRESERVE_P (</code><var>x</var><code>)</code><dd>In a <code>code_label</code> or <code>note</code>, indicates that the label is referenced by
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code or data not visible to the RTL of a given function.
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Labels referenced by a non-local goto will have this bit set. Stored
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in the <code>in_struct</code> field and printed as ‘<samp><span class="samp">/s</span></samp>’.
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<p><a name="index-LABEL_005fREF_005fNONLOCAL_005fP-2638"></a><a name="index-g_t_0040code_007blabel_005fref_007d-and-_0040samp_007b_002fv_007d-2639"></a><a name="index-g_t_0040code_007breg_005flabel_007d-and-_0040samp_007b_002fv_007d-2640"></a><a name="index-g_t_0040code_007bvolatil_007d_002c-in-_0040code_007blabel_005fref_007d-and-_0040code_007breg_005flabel_007d-2641"></a><br><dt><code>LABEL_REF_NONLOCAL_P (</code><var>x</var><code>)</code><dd>In <code>label_ref</code> and <code>reg_label</code> expressions, nonzero if this is
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a reference to a non-local label.
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Stored in the <code>volatil</code> field and printed as ‘<samp><span class="samp">/v</span></samp>’.
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<p><a name="index-MEM_005fKEEP_005fALIAS_005fSET_005fP-2642"></a><a name="index-g_t_0040code_007bmem_007d-and-_0040samp_007b_002fj_007d-2643"></a><a name="index-g_t_0040code_007bjump_007d_002c-in-_0040code_007bmem_007d-2644"></a><br><dt><code>MEM_KEEP_ALIAS_SET_P (</code><var>x</var><code>)</code><dd>In <code>mem</code> expressions, 1 if we should keep the alias set for this
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mem unchanged when we access a component. Set to 1, for example, when we
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are already in a non-addressable component of an aggregate.
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Stored in the <code>jump</code> field and printed as ‘<samp><span class="samp">/j</span></samp>’.
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<p><a name="index-MEM_005fVOLATILE_005fP-2645"></a><a name="index-g_t_0040code_007bmem_007d-and-_0040samp_007b_002fv_007d-2646"></a><a name="index-g_t_0040code_007basm_005finput_007d-and-_0040samp_007b_002fv_007d-2647"></a><a name="index-g_t_0040code_007basm_005foperands_007d-and-_0040samp_007b_002fv_007d-2648"></a><a name="index-g_t_0040code_007bvolatil_007d_002c-in-_0040code_007bmem_007d_002c-_0040code_007basm_005foperands_007d_002c-and-_0040code_007basm_005finput_007d-2649"></a><br><dt><code>MEM_VOLATILE_P (</code><var>x</var><code>)</code><dd>In <code>mem</code>, <code>asm_operands</code>, and <code>asm_input</code> expressions,
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nonzero for volatile memory references.
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Stored in the <code>volatil</code> field and printed as ‘<samp><span class="samp">/v</span></samp>’.
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<p><a name="index-MEM_005fNOTRAP_005fP-2650"></a><a name="index-g_t_0040code_007bmem_007d-and-_0040samp_007b_002fc_007d-2651"></a><a name="index-g_t_0040code_007bcall_007d_002c-in-_0040code_007bmem_007d-2652"></a><br><dt><code>MEM_NOTRAP_P (</code><var>x</var><code>)</code><dd>In <code>mem</code>, nonzero for memory references that will not trap.
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Stored in the <code>call</code> field and printed as ‘<samp><span class="samp">/c</span></samp>’.
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<p><a name="index-MEM_005fPOINTER-2653"></a><a name="index-g_t_0040code_007bmem_007d-and-_0040samp_007b_002ff_007d-2654"></a><a name="index-g_t_0040code_007bframe_005frelated_007d_002c-in-_0040code_007bmem_007d-2655"></a><br><dt><code>MEM_POINTER (</code><var>x</var><code>)</code><dd>Nonzero in a <code>mem</code> if the memory reference holds a pointer.
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Stored in the <code>frame_related</code> field and printed as ‘<samp><span class="samp">/f</span></samp>’.
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<p><a name="index-REG_005fFUNCTION_005fVALUE_005fP-2656"></a><a name="index-g_t_0040code_007breg_007d-and-_0040samp_007b_002fi_007d-2657"></a><a name="index-g_t_0040code_007breturn_005fval_007d_002c-in-_0040code_007breg_007d-2658"></a><br><dt><code>REG_FUNCTION_VALUE_P (</code><var>x</var><code>)</code><dd>Nonzero in a <code>reg</code> if it is the place in which this function's
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value is going to be returned. (This happens only in a hard
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register.) Stored in the <code>return_val</code> field and printed as
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‘<samp><span class="samp">/i</span></samp>’.
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<p><a name="index-REG_005fPOINTER-2659"></a><a name="index-g_t_0040code_007breg_007d-and-_0040samp_007b_002ff_007d-2660"></a><a name="index-g_t_0040code_007bframe_005frelated_007d_002c-in-_0040code_007breg_007d-2661"></a><br><dt><code>REG_POINTER (</code><var>x</var><code>)</code><dd>Nonzero in a <code>reg</code> if the register holds a pointer. Stored in the
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<code>frame_related</code> field and printed as ‘<samp><span class="samp">/f</span></samp>’.
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<p><a name="index-REG_005fUSERVAR_005fP-2662"></a><a name="index-g_t_0040code_007breg_007d-and-_0040samp_007b_002fv_007d-2663"></a><a name="index-g_t_0040code_007bvolatil_007d_002c-in-_0040code_007breg_007d-2664"></a><br><dt><code>REG_USERVAR_P (</code><var>x</var><code>)</code><dd>In a <code>reg</code>, nonzero if it corresponds to a variable present in
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the user's source code. Zero for temporaries generated internally by
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the compiler. Stored in the <code>volatil</code> field and printed as
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‘<samp><span class="samp">/v</span></samp>’.
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<p>The same hard register may be used also for collecting the values of
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functions called by this one, but <code>REG_FUNCTION_VALUE_P</code> is zero
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in this kind of use.
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<p><a name="index-RTX_005fFRAME_005fRELATED_005fP-2665"></a><a name="index-g_t_0040code_007binsn_007d-and-_0040samp_007b_002ff_007d-2666"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002ff_007d-2667"></a><a name="index-g_t_0040code_007bjump_005finsn_007d-and-_0040samp_007b_002ff_007d-2668"></a><a name="index-g_t_0040code_007bbarrier_007d-and-_0040samp_007b_002ff_007d-2669"></a><a name="index-g_t_0040code_007bset_007d-and-_0040samp_007b_002ff_007d-2670"></a><a name="index-g_t_0040code_007bframe_005frelated_007d_002c-in-_0040code_007binsn_007d_002c-_0040code_007bcall_005finsn_007d_002c-_0040code_007bjump_005finsn_007d_002c-_0040code_007bbarrier_007d_002c-and-_0040code_007bset_007d-2671"></a><br><dt><code>RTX_FRAME_RELATED_P (</code><var>x</var><code>)</code><dd>Nonzero in an <code>insn</code>, <code>call_insn</code>, <code>jump_insn</code>,
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<code>barrier</code>, or <code>set</code> which is part of a function prologue
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and sets the stack pointer, sets the frame pointer, or saves a register.
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This flag should also be set on an instruction that sets up a temporary
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register to use in place of the frame pointer.
|
||
|
|
Stored in the <code>frame_related</code> field and printed as ‘<samp><span class="samp">/f</span></samp>’.
|
||
|
|
|
||
|
|
<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>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>This flag is required for exception handling support on targets with RTL
|
||
|
|
prologues.
|
||
|
|
|
||
|
|
<p><a name="index-MEM_005fREADONLY_005fP-2672"></a><a name="index-g_t_0040code_007bmem_007d-and-_0040samp_007b_002fu_007d-2673"></a><a name="index-g_t_0040code_007bunchanging_007d_002c-in-_0040code_007bmem_007d-2674"></a><br><dt><code>MEM_READONLY_P (</code><var>x</var><code>)</code><dd>Nonzero in a <code>mem</code>, if the memory is statically allocated and read-only.
|
||
|
|
|
||
|
|
<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>Stored in the <code>unchanging</code> field and printed as ‘<samp><span class="samp">/u</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-SCHED_005fGROUP_005fP-2675"></a><a name="index-g_t_0040code_007binsn_007d-and-_0040samp_007b_002fs_007d-2676"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002fs_007d-2677"></a><a name="index-g_t_0040code_007bjump_005finsn_007d-and-_0040samp_007b_002fs_007d-2678"></a><a name="index-g_t_0040code_007bjump_005ftable_005fdata_007d-and-_0040samp_007b_002fs_007d-2679"></a><a name="index-g_t_0040code_007bin_005fstruct_007d_002c-in-_0040code_007binsn_007d_002c-_0040code_007bcall_005finsn_007d_002c-_0040code_007bjump_005finsn_007d-and-_0040code_007bjump_005ftable_005fdata_007d-2680"></a><br><dt><code>SCHED_GROUP_P (</code><var>x</var><code>)</code><dd>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><span class="samp">/s</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-SET_005fIS_005fRETURN_005fP-2681"></a><a name="index-g_t_0040code_007binsn_007d-and-_0040samp_007b_002fj_007d-2682"></a><a name="index-g_t_0040code_007bjump_007d_002c-in-_0040code_007binsn_007d-2683"></a><br><dt><code>SET_IS_RETURN_P (</code><var>x</var><code>)</code><dd>For a <code>set</code>, nonzero if it is for a return.
|
||
|
|
Stored in the <code>jump</code> field and printed as ‘<samp><span class="samp">/j</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-SIBLING_005fCALL_005fP-2684"></a><a name="index-g_t_0040code_007bcall_005finsn_007d-and-_0040samp_007b_002fj_007d-2685"></a><a name="index-g_t_0040code_007bjump_007d_002c-in-_0040code_007bcall_005finsn_007d-2686"></a><br><dt><code>SIBLING_CALL_P (</code><var>x</var><code>)</code><dd>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><span class="samp">/j</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-STRING_005fPOOL_005fADDRESS_005fP-2687"></a><a name="index-g_t_0040code_007bsymbol_005fref_007d-and-_0040samp_007b_002ff_007d-2688"></a><a name="index-g_t_0040code_007bframe_005frelated_007d_002c-in-_0040code_007bsymbol_005fref_007d-2689"></a><br><dt><code>STRING_POOL_ADDRESS_P (</code><var>x</var><code>)</code><dd>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><span class="samp">/f</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-SUBREG_005fPROMOTED_005fUNSIGNED_005fP-2690"></a><a name="index-g_t_0040code_007bsubreg_007d-and-_0040samp_007b_002fu_007d-and-_0040samp_007b_002fv_007d-2691"></a><a name="index-g_t_0040code_007bunchanging_007d_002c-in-_0040code_007bsubreg_007d-2692"></a><a name="index-g_t_0040code_007bvolatil_007d_002c-in-_0040code_007bsubreg_007d-2693"></a><br><dt><code>SUBREG_PROMOTED_UNSIGNED_P (</code><var>x</var><code>)</code><dd>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><span class="samp">/u</span></samp>’ and ‘<samp><span class="samp">/v</span></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-2694"></a><a name="index-g_t_0040code_007bsubreg_007d-and-_0040samp_007b_002fu_007d-2695"></a><a name="index-g_t_0040code_007bunchanging_007d_002c-in-_0040code_007bsubreg_007d-2696"></a><a name="index-g_t_0040code_007bvolatil_007d_002c-in-_0040code_007bsubreg_007d-2697"></a><br><dt><code>SUBREG_PROMOTED_UNSIGNED_SET (</code><var>x</var><code>)</code><dd>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-2698"></a><a name="index-g_t_0040code_007bsubreg_007d-and-_0040samp_007b_002fs_007d-2699"></a><a name="index-g_t_0040code_007bin_005fstruct_007d_002c-in-_0040code_007bsubreg_007d-2700"></a><br><dt><code>SUBREG_PROMOTED_VAR_P (</code><var>x</var><code>)</code><dd>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><span class="samp">/s</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-SYMBOL_005fREF_005fUSED-2701"></a><a name="index-g_t_0040code_007bused_007d_002c-in-_0040code_007bsymbol_005fref_007d-2702"></a><br><dt><code>SYMBOL_REF_USED (</code><var>x</var><code>)</code><dd>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-2703"></a><a name="index-g_t_0040code_007bsymbol_005fref_007d-and-_0040samp_007b_002fi_007d-2704"></a><a name="index-g_t_0040code_007breturn_005fval_007d_002c-in-_0040code_007bsymbol_005fref_007d-2705"></a><br><dt><code>SYMBOL_REF_WEAK (</code><var>x</var><code>)</code><dd>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><span class="samp">/i</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-SYMBOL_005fREF_005fFLAG-2706"></a><a name="index-g_t_0040code_007bsymbol_005fref_007d-and-_0040samp_007b_002fv_007d-2707"></a><a name="index-g_t_0040code_007bvolatil_007d_002c-in-_0040code_007bsymbol_005fref_007d-2708"></a><br><dt><code>SYMBOL_REF_FLAG (</code><var>x</var><code>)</code><dd>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><span class="samp">/v</span></samp>’.
|
||
|
|
|
||
|
|
<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><a name="index-PREFETCH_005fSCHEDULE_005fBARRIER_005fP-2709"></a><a name="index-g_t_0040code_007bprefetch_007d-and-_0040samp_007b_002fv_007d-2710"></a><a name="index-g_t_0040code_007bvolatile_007d_002c-in-_0040code_007bprefetch_007d-2711"></a><br><dt><code>PREFETCH_SCHEDULE_BARRIER_P (</code><var>x</var><code>)</code><dd>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><span class="samp">/v</span></samp>’.
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>These are the fields to which the above macros refer:
|
||
|
|
|
||
|
|
|
||
|
|
<a name="index-call-2712"></a>
|
||
|
|
<a name="index-g_t_0040samp_007b_002fc_007d-in-RTL-dump-2713"></a>
|
||
|
|
<dl><dt><code>call</code><dd>In a <code>mem</code>, 1 means that the memory reference will not trap.
|
||
|
|
|
||
|
|
<p>In a <code>call</code>, 1 means that this pure or const call may possibly
|
||
|
|
infinite loop.
|
||
|
|
|
||
|
|
<p>In an RTL dump, this flag is represented as ‘<samp><span class="samp">/c</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-frame_005frelated-2714"></a><a name="index-g_t_0040samp_007b_002ff_007d-in-RTL-dump-2715"></a><br><dt><code>frame_related</code><dd>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>In <code>reg</code> expressions, 1 means that the register holds a pointer.
|
||
|
|
|
||
|
|
<p>In <code>mem</code> expressions, 1 means that the memory reference holds a pointer.
|
||
|
|
|
||
|
|
<p>In <code>symbol_ref</code> expressions, 1 means that the reference addresses
|
||
|
|
this function's string constant pool.
|
||
|
|
|
||
|
|
<p>In an RTL dump, this flag is represented as ‘<samp><span class="samp">/f</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-in_005fstruct-2716"></a><a name="index-g_t_0040samp_007b_002fs_007d-in-RTL-dump-2717"></a><br><dt><code>in_struct</code><dd>In <code>reg</code> expressions, it is 1 if the register has its entire life
|
||
|
|
contained within the test expression of some loop.
|
||
|
|
|
||
|
|
<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>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>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>In an <code>insn</code> during dead-code elimination, 1 means that the insn is
|
||
|
|
dead code.
|
||
|
|
|
||
|
|
<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>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>In an RTL dump, this flag is represented as ‘<samp><span class="samp">/s</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-return_005fval-2718"></a><a name="index-g_t_0040samp_007b_002fi_007d-in-RTL-dump-2719"></a><br><dt><code>return_val</code><dd>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>In <code>symbol_ref</code> expressions, 1 means the referenced symbol is weak.
|
||
|
|
|
||
|
|
<p>In <code>call</code> expressions, 1 means the call is pure.
|
||
|
|
|
||
|
|
<p>In an RTL dump, this flag is represented as ‘<samp><span class="samp">/i</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-jump-2720"></a><a name="index-g_t_0040samp_007b_002fj_007d-in-RTL-dump-2721"></a><br><dt><code>jump</code><dd>In a <code>mem</code> expression, 1 means we should keep the alias set for this
|
||
|
|
mem unchanged when we access a component.
|
||
|
|
|
||
|
|
<p>In a <code>set</code>, 1 means it is for a return.
|
||
|
|
|
||
|
|
<p>In a <code>call_insn</code>, 1 means it is a sibling call.
|
||
|
|
|
||
|
|
<p>In an RTL dump, this flag is represented as ‘<samp><span class="samp">/j</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-unchanging-2722"></a><a name="index-g_t_0040samp_007b_002fu_007d-in-RTL-dump-2723"></a><br><dt><code>unchanging</code><dd>In <code>reg</code> and <code>mem</code> expressions, 1 means
|
||
|
|
that the value of the expression never changes.
|
||
|
|
|
||
|
|
<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>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>In a <code>symbol_ref</code> expression, 1 means that this symbol addresses
|
||
|
|
something in the per-function constant pool.
|
||
|
|
|
||
|
|
<p>In a <code>call_insn</code> 1 means that this instruction is a call to a const
|
||
|
|
function.
|
||
|
|
|
||
|
|
<p>In an RTL dump, this flag is represented as ‘<samp><span class="samp">/u</span></samp>’.
|
||
|
|
|
||
|
|
<p><a name="index-used-2724"></a><br><dt><code>used</code><dd>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>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>In a <code>symbol_ref</code>, it indicates that an external declaration for
|
||
|
|
the symbol has already been written.
|
||
|
|
|
||
|
|
<p><a name="index-volatil-2725"></a><a name="index-g_t_0040samp_007b_002fv_007d-in-RTL-dump-2726"></a><br><dt><code>volatil</code><dd><a name="index-volatile-memory-references-2727"></a>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>In a <code>symbol_ref</code> expression, it is used for machine-specific
|
||
|
|
purposes.
|
||
|
|
|
||
|
|
<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>In an <code>insn</code>, 1 means the insn has been deleted.
|
||
|
|
|
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<p>In <code>label_ref</code> and <code>reg_label</code> expressions, 1 means a reference
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to a non-local label.
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<p>In <code>prefetch</code> expressions, 1 means that the containing insn is a
|
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scheduling barrier.
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<p>In an RTL dump, this flag is represented as ‘<samp><span class="samp">/v</span></samp>’.
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</dl>
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</body></html>
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