fix Issue 16400 - naked variadic C function emits broken prologue

dlang · Aug 12, 2020 · 07e354a · 07e354a
1 parent 3125bb1
commit 07e354a
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diff --git a/src/dmd/backend/cgelem.d b/src/dmd/backend/cgelem.d
@@ -5063,6 +5063,13 @@ private elem * elvalist(elem *e, goal_t goal)
 {
     assert(e.Eoper == OPva_start);
 
+    if (funcsym_p.ty() & mTYnaked)
+    {   // do not generate prolog
+        el_free(e);
+        e = el_long(TYint, 0);
+        return e;
+    }
+
     if (I32)
     {
         // (OPva_start &va)

diff --git a/test/runnable/iasm.d b/test/runnable/iasm.d
@@ -4828,6 +4828,21 @@ L1:     pop     EAX;
 }
 
 /****************************************************/
+// https://issues.dlang.org/show_bug.cgi?id=16400
+
+extern(C) void f16400(int, ...)
+{
+	asm {naked; ret;}
+}
+
+void test16400()
+{
+	assert(*(cast(ubyte*) &f16400) == 0xc3); // fails
+	f16400(0); // corrupts the stack
+}
+
+/****************************************************/
+
 int main()
 {
     printf("Testing iasm.d\n");
@@ -4902,6 +4917,7 @@ int main()
     test60();
     test9866();
     test17027();
+    test16400();
   }
     printf("Success\n");
     return 0;