Fix alloca support for Cygwin. On cygwin its __alloca not __builtin_alloca
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19776 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index 0efdb65..6195b76 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -723,7 +723,10 @@
static void generateCompilerSpecificCode(std::ostream& Out) {
// Alloca is hard to get, and we don't want to include stdlib.h here...
Out << "/* get a declaration for alloca */\n"
- << "#if defined(__CYGWIN__) || defined(__APPLE__)\n"
+ << "#if defined(__CYGWIN__)\n"
+ << "extern void *_alloca(unsigned long);\n"
+ << "#define alloca(x) _alloca(x)\n"
+ << "#elif defined(__APPLE__)\n"
<< "extern void *__builtin_alloca(unsigned long);\n"
<< "#define alloca(x) __builtin_alloca(x)\n"
<< "#elif defined(__sun__)\n"