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| <a name="Permitting-tail-calls"></a> |
| <h4 class="subsection">17.9.13 Permitting tail calls</h4> |
| <a name="index-tail-calls"></a> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fFUNCTION_005fOK_005fFOR_005fSIBCALL"></a>Target Hook: <em>bool</em> <strong>TARGET_FUNCTION_OK_FOR_SIBCALL</strong> <em>(tree <var>decl</var>, tree <var>exp</var>)</em></dt> |
| <dd><p>True if it is OK to do sibling call optimization for the specified |
| call expression <var>exp</var>. <var>decl</var> will be the called function, |
| or <code>NULL</code> if this is an indirect call. |
| </p> |
| <p>It is not uncommon for limitations of calling conventions to prevent |
| tail calls to functions outside the current unit of translation, or |
| during PIC compilation. The hook is used to enforce these restrictions, |
| as the <code>sibcall</code> md pattern can not fail, or fall over to a |
| “normal” call. The criteria for successful sibling call optimization |
| may vary greatly between different architectures. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fEXTRA_005fLIVE_005fON_005fENTRY"></a>Target Hook: <em>void</em> <strong>TARGET_EXTRA_LIVE_ON_ENTRY</strong> <em>(bitmap <var>regs</var>)</em></dt> |
| <dd><p>Add any hard registers to <var>regs</var> that are live on entry to the |
| function. This hook only needs to be defined to provide registers that |
| cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved |
| registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM, |
| TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES, |
| FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fSET_005fUP_005fBY_005fPROLOGUE"></a>Target Hook: <em>void</em> <strong>TARGET_SET_UP_BY_PROLOGUE</strong> <em>(struct hard_reg_set_container *<var></var>)</em></dt> |
| <dd><p>This hook should add additional registers that are computed by the prologue to the hard regset for shrink-wrapping optimization purposes. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fWARN_005fFUNC_005fRETURN"></a>Target Hook: <em>bool</em> <strong>TARGET_WARN_FUNC_RETURN</strong> <em>(tree)</em></dt> |
| <dd><p>True if a function’s return statements should be checked for matching the function’s return type. This includes checking for falling off the end of a non-void function. Return false if no such check should be made. |
| </p></dd></dl> |
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