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| <hr> |
| <a name="Flags-in-an-RTL-Expression"></a> |
| <h3 class="section">13.5 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-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-RTL_005fCONST_005fCALL_005fP"></a> |
| <a name="index-call_005finsn-and-_002fu"></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-INSN_005fANNULLED_005fBRANCH_005fP"></a> |
| <a name="index-jump_005finsn-and-_002fu"></a> |
| <a name="index-call_005finsn-and-_002fu-1"></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-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-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-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-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> |
| <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></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 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> |
| </dd> |
| <dt><code>volatil</code></dt> |
| <dd><a name="index-volatile-memory-references"></a> |
| <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> |
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