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//===----- trampoline_setup.c - Implement __trampoline_setup -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include <stdint.h>
#include <stdlib.h>
extern void __clear_cache(void* start, void* end);
//
// The ppc compiler generates calls to __trampoline_setup() when creating
// trampoline functions on the stack for use with nested functions.
// This function creates a custom 40-byte trampoline function on the stack
// which loads r11 with a pointer to the outer function's locals
// and then jumps to the target nested function.
//
#if __ppc__
void __trampoline_setup(uint32_t* trampOnStack, int trampSizeAllocated,
const void* realFunc, void* localsPtr)
{
// should never happen, but if compiler did not allocate
// enough space on stack for the trampoline, abort
if ( trampSizeAllocated < 40 )
abort();
// create trampoline
trampOnStack[0] = 0x7c0802a6; // mflr r0
trampOnStack[1] = 0x4800000d; // bl Lbase
trampOnStack[2] = (uint32_t)realFunc;
trampOnStack[3] = (uint32_t)localsPtr;
trampOnStack[4] = 0x7d6802a6; // Lbase: mflr r11
trampOnStack[5] = 0x818b0000; // lwz r12,0(r11)
trampOnStack[6] = 0x7c0803a6; // mtlr r0
trampOnStack[7] = 0x7d8903a6; // mtctr r12
trampOnStack[8] = 0x816b0004; // lwz r11,4(r11)
trampOnStack[9] = 0x4e800420; // bctr
// clear instruction cache
__clear_cache(trampOnStack, &trampOnStack[10]);
}
#endif // __ppc__
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