1 files changed, 43 insertions, 0 deletions
diff --git a/compiler-rt/lib/builtins/trampoline_setup.c b/compiler-rt/lib/builtins/trampoline_setup.c
new file mode 100644
index 000000000000..a62431723d78
--- /dev/null
+++ b/compiler-rt/lib/builtins/trampoline_setup.c
@@ -0,0 +1,43 @@
+//===----- trampoline_setup.c - Implement __trampoline_setup -------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.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__ && !defined(__powerpc64__)
+COMPILER_RT_ABI 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)
+    compilerrt_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__ && !defined(__powerpc64__)