1 files changed, 46 insertions, 0 deletions
diff --git a/lib/trampoline_setup.c b/lib/trampoline_setup.c
new file mode 100644
index 000000000..a8906bcc0
--- /dev/null
+++ b/lib/trampoline_setup.c
@@ -0,0 +1,46 @@
+//===----- 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__