[OCaml] Fix incorrect use of CAMLlocal in nested blocks

Summary:
The OCaml manual states:

> Local variables of type value must be declared with one of the
> CAMLlocal macros. [...] These macros must be used at the beginning
> of the function, not in a nested block.

This patch moves several instances of CAMLlocal macros from nested
blocks to the function beginning.

Reviewers: whitequark

Reviewed By: whitequark

Subscribers: CodaFi, llvm-commits

Differential Revision: https://reviews.llvm.org/D53841

llvm-svn: 346387

llvm/bindings/ocaml/llvm/llvm_ocaml.c

@@ -483,9 +483,9 @@ CAMLprim value llvm_struct_set_body(LLVMTypeRef Ty,
 CAMLprim value llvm_struct_name(LLVMTypeRef Ty)
 {
   CAMLparam0();
+  CAMLlocal1(result);
   const char *C = LLVMGetStructName(Ty);
   if (C) {
-    CAMLlocal1(result);
     result = caml_alloc_small(1, 0);
     Store_field(result, 0, caml_copy_string(C));
     CAMLreturn(result);
@@ -636,6 +636,7 @@ enum ValueKind {
 
 CAMLprim value llvm_classify_value(LLVMValueRef Val) {
   CAMLparam0();
+  CAMLlocal1(result);
   if (!Val)
     CAMLreturn(Val_int(NullValue));
   if (LLVMIsAConstant(Val)) {
@@ -652,7 +653,6 @@ CAMLprim value llvm_classify_value(LLVMValueRef Val) {
     DEFINE_CASE(Val, ConstantVector);
   }
   if (LLVMIsAInstruction(Val)) {
-    CAMLlocal1(result);
     result = caml_alloc_small(1, 0);
     Store_field(result, 0, Val_int(LLVMGetInstructionOpcode(Val)));
     CAMLreturn(result);
@@ -822,12 +822,11 @@ CAMLprim LLVMValueRef llvm_mdnull(LLVMContextRef C) {
 /* llvalue -> string option */
 CAMLprim value llvm_get_mdstring(LLVMValueRef V) {
   CAMLparam0();
+  CAMLlocal2(Option, Str);
   const char *S;
   unsigned Len;
 
   if ((S = LLVMGetMDString(V, &Len))) {
-    CAMLlocal2(Option, Str);
-
     Str = caml_alloc_string(Len);
     memcpy(String_val(Str), S, Len);
     Option = alloc(1,0);