Set correct calling convention even if there is a bitcast in the way.
This attempts to fix PR4239.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72251 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 718a515..356caa3 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -2100,7 +2100,7 @@
   }
 
   CS.setAttributes(Attrs);
-  if (const llvm::Function *F = dyn_cast<llvm::Function>(Callee))
+  if (const llvm::Function *F =  dyn_cast<llvm::Function>(Callee->stripPointerCasts()))
     CS.setCallingConv(F->getCallingConv());
 
   // If the call doesn't return, finish the basic block and clear the
diff --git a/test/CodeGen/2009-05-22-callingconv.c b/test/CodeGen/2009-05-22-callingconv.c
new file mode 100644
index 0000000..2b70d84
--- /dev/null
+++ b/test/CodeGen/2009-05-22-callingconv.c
@@ -0,0 +1,25 @@
+// RUN: clang-cc %s -emit-llvm -o - | grep call | grep x86_stdcallcc
+void abort(void) __attribute__((__noreturn__));
+typedef void re_string_t;
+typedef void re_dfa_t;
+typedef int reg_errcode_t;
+static reg_errcode_t re_string_construct (re_string_t *pstr, const char *str,
+       int len, char * trans,
+       int icase, const re_dfa_t *dfa)
+     __attribute__ ((regparm (3), stdcall));
+static reg_errcode_t
+re_string_construct (pstr, str, len, trans, icase, dfa)
+     re_string_t *pstr;
+     const char *str;
+     int len, icase;
+     char * trans;
+     const re_dfa_t *dfa;
+{
+        if (dfa != (void*)0x282020c0)
+                abort();
+return 0;
+}
+int main()
+{
+  return re_string_construct(0, 0, 0, 0, 0, (void*)0x282020c0);
+}