vendor/compiler-rt/compiler-rt-r224034

1 files changed, 48 insertions, 0 deletions

diff --git a/lib/builtins/trampoline_setup.c b/lib/builtins/trampoline_setup.c
new file mode 100644
index 0000000000000..25b627ab7658d
--- /dev/null
+++ b/lib/builtins/trampoline_setup.c
@@ -0,0 +1,48 @@
+/* ===----- trampoline_setup.c - Implement __trampoline_setup -------------===
+ *
+ *                     The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#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__) */