From 85befc81327eb73b18ac4036f841d2d7bfadecd3 Mon Sep 17 00:00:00 2001
From: xleroy <xleroy@fca1b0fc-160b-0410-b1d3-a4f43f01ea2e>
Date: Mon, 24 Feb 2014 16:52:39 +0000
Subject: Do not transform __builtin_va_arg for a struct or union type, this
 causes an ugly error message in the back-end.  Rather, leave it as is, and
 let C2C handle the error.

git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2422 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
---
 cparser/StructReturn.ml | 68 +++++++++++++++++++++++++++----------------------
 1 file changed, 37 insertions(+), 31 deletions(-)

diff --git a/cparser/StructReturn.ml b/cparser/StructReturn.ml
index 91d5f4f..e13b09d 100644
--- a/cparser/StructReturn.ml
+++ b/cparser/StructReturn.ml
@@ -136,37 +136,43 @@ and transf_call env ctx opt_lhs fn args ty =
     match opt_lhs with
     | None -> e
     | Some lhs -> eassign (transf_expr env Val lhs) e in
-  match classify_return env ty with
-  | Ret_scalar ->
-      opt_eassign {edesc = ECall(fn', args'); etyp = ty'}
-  | Ret_ref ->
-      begin match ctx, opt_lhs with
-      | Effects, None ->
-          let tmp = new_temp ~name:"_res" ty in
-          {edesc = ECall(fn', eaddrof tmp :: args'); etyp = TVoid []}
-      | Effects, Some lhs ->
-          let lhs' = transf_expr env Val lhs in
-          {edesc = ECall(fn', eaddrof lhs' :: args'); etyp = TVoid []}
-      | Val, None ->
-          let tmp = new_temp ~name:"_res" ty in
-          ecomma {edesc = ECall(fn', eaddrof tmp :: args'); etyp = TVoid []} tmp
-      | Val, Some lhs ->
-          let lhs' = transf_expr env Val lhs in
-          let tmp = new_temp ~name:"_res" ty in
-          ecomma {edesc = ECall(fn', eaddrof tmp :: args'); etyp = TVoid []}
-                 (eassign lhs' tmp)
-      end
-  | Ret_value ty_ret ->
-      let ecall = {edesc = ECall(fn', args'); etyp = ty_ret} in
-      begin match ctx, opt_lhs with
-      | Effects, None ->
-          ecall
-      | _, _ ->
-          let tmp = new_temp ~name:"_res" ty_ret in
-          opt_eassign
-            (ecomma (eassign tmp ecall)
-                    (ereinterpret ty' tmp))
-      end
+  match fn with
+  | {edesc = EVar {name = "__builtin_va_arg"}} ->
+      (* Do not transform the call in this case *)
+      opt_eassign {edesc = ECall(fn, args'); etyp = ty}
+  | _ ->
+    match classify_return env ty with
+    | Ret_scalar ->
+        opt_eassign {edesc = ECall(fn', args'); etyp = ty'}
+    | Ret_ref ->
+        begin match ctx, opt_lhs with
+        | Effects, None ->
+            let tmp = new_temp ~name:"_res" ty in
+            {edesc = ECall(fn', eaddrof tmp :: args'); etyp = TVoid []}
+        | Effects, Some lhs ->
+            let lhs' = transf_expr env Val lhs in
+            {edesc = ECall(fn', eaddrof lhs' :: args'); etyp = TVoid []}
+        | Val, None ->
+            let tmp = new_temp ~name:"_res" ty in
+            ecomma {edesc = ECall(fn', eaddrof tmp :: args'); etyp = TVoid []}
+                   tmp
+        | Val, Some lhs ->
+            let lhs' = transf_expr env Val lhs in
+            let tmp = new_temp ~name:"_res" ty in
+            ecomma {edesc = ECall(fn', eaddrof tmp :: args'); etyp = TVoid []}
+                   (eassign lhs' tmp)
+        end
+    | Ret_value ty_ret ->
+        let ecall = {edesc = ECall(fn', args'); etyp = ty_ret} in
+        begin match ctx, opt_lhs with
+        | Effects, None ->
+            ecall
+        | _, _ ->
+            let tmp = new_temp ~name:"_res" ty_ret in
+            opt_eassign
+              (ecomma (eassign tmp ecall)
+                      (ereinterpret ty' tmp))
+        end
 
 (* Initializers *)
 
-- 
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