trampoline_setup.c revision 276851 
138095Speter/* ===----- trampoline_setup.c - Implement __trampoline_setup -------------===
264567Sgshapiro *
338095Speter *                     The LLVM Compiler Infrastructure
467660Sgshapiro *
567660Sgshapiro * This file is dual licensed under the MIT and the University of Illinois Open
680029Sobrien * Source Licenses. See LICENSE.TXT for details.
780029Sobrien *
864567Sgshapiro * ===----------------------------------------------------------------------===
938095Speter */
1074816Sru
1138095Speter#include "int_lib.h"
1280029Sobrien
1380029Sobrienextern void __clear_cache(void* start, void* end);
1464567Sgshapiro
1564567Sgshapiro/*
1664567Sgshapiro * The ppc compiler generates calls to __trampoline_setup() when creating
1764567Sgshapiro * trampoline functions on the stack for use with nested functions.
1864567Sgshapiro * This function creates a custom 40-byte trampoline function on the stack
1964567Sgshapiro * which loads r11 with a pointer to the outer function's locals
2038095Speter * and then jumps to the target nested function.
2166961Sgshapiro */
2266961Sgshapiro
2364567Sgshapiro#if __ppc__ && !defined(__powerpc64__)
2465970SgshapiroCOMPILER_RT_ABI void
2580029Sobrien__trampoline_setup(uint32_t* trampOnStack, int trampSizeAllocated,
2680029Sobrien                   const void* realFunc, void* localsPtr)
2780029Sobrien{
2880029Sobrien    /* should never happen, but if compiler did not allocate */
2965970Sgshapiro    /* enough space on stack for the trampoline, abort */
3038095Speter    if ( trampSizeAllocated < 40 )
31        compilerrt_abort();
32
33    /* create trampoline */
34    trampOnStack[0] = 0x7c0802a6;    /* mflr r0 */
35    trampOnStack[1] = 0x4800000d;    /* bl Lbase */
36    trampOnStack[2] = (uint32_t)realFunc;
37    trampOnStack[3] = (uint32_t)localsPtr;
38    trampOnStack[4] = 0x7d6802a6;    /* Lbase: mflr r11 */
39    trampOnStack[5] = 0x818b0000;    /* lwz    r12,0(r11) */
40    trampOnStack[6] = 0x7c0803a6;    /* mtlr r0 */
41    trampOnStack[7] = 0x7d8903a6;    /* mtctr r12 */
42    trampOnStack[8] = 0x816b0004;    /* lwz    r11,4(r11) */
43    trampOnStack[9] = 0x4e800420;    /* bctr */
44
45    /* clear instruction cache */
46    __clear_cache(trampOnStack, &trampOnStack[10]);
47}
48#endif /* __ppc__ && !defined(__powerpc64__) */
49