Reflecting commit r14943 on version/4.02:

PR#6082: on x86-32, enforce 16-byte stack alignment for compatibility
with recent GCC and Clang.  Win32/MSVC keeps 4-byte stack alignment.


git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@14944 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

Changes

@@ -162,6 +162,9 @@ Bug fixes:
   (Damien Doligez)
 - PR#5820: Fix camlp4 lexer roll back problem
   (Hongbo Zhang)
+- PR#6038: on x86-32, enforce 16-byte stack alignment for compatibility
+  with recent GCC and Clang.  Win32/MSVC keeps 4-byte stack alignment.
+  (Xavier Leroy)
 - PR#6062: Fix a regression bug caused by commit 13047
   (Hongbo Zhang, report by Christophe Troestler)
 - PR#6109: Typos in ocamlbuild error messages

asmcomp/i386/arch.ml

@@ -155,5 +155,7 @@ let print_specific_operation printreg op ppf arg =
 
 let stack_alignment =
   match Config.system with
-  | "macosx" -> 16
-  | _ -> 4
+  | "win32" -> 4     (* MSVC *)
+  | _ -> 16
+(* PR#6038: GCC and Clang seem to require 16-byte alignment nowadays,
+   even if only MacOS X's ABI formally requires it *)

asmrun/i386.S

@@ -115,13 +115,10 @@
 #define PROFILE_C
 #endif
 
-#ifdef SYS_macosx
+/* PR#6038: GCC and Clang seem to require 16-byte alignment nowadays,
+   even if only MacOS X's ABI formally requires it. */	
 #define ALIGN_STACK(amount) subl $ amount, %esp ; CFI_ADJUST(amount)
 #define UNDO_ALIGN_STACK(amount) addl $ amount, %esp ; CFI_ADJUST(-amount)
-#else
-#define ALIGN_STACK(amount)
-#define UNDO_ALIGN_STACK(amount)
-#endif
 
 /* Allocation */
 
@@ -304,11 +301,7 @@ LBL(106):
 LBL(107):
     /* Pop the exception handler */
         popl    G(caml_exception_pointer); CFI_ADJUST(-4)
-#ifdef SYS_macosx
         addl    $12, %esp       ; CFI_ADJUST(-12)
-#else
-        addl    $4, %esp        ; CFI_ADJUST(-4)
-#endif
 LBL(109):
     /* Pop the callback link, restoring the global variables */
         popl    G(caml_bottom_of_stack); CFI_ADJUST(-4)
@@ -461,10 +454,8 @@ FUNCTION(caml_ml_array_bound_error)
         movl    %edx, G(caml_last_return_address)
         leal    4(%esp), %edx
         movl    %edx, G(caml_bottom_of_stack)
-    /* For MacOS X: re-align the stack */
-#ifdef SYS_macosx
+    /* Re-align the stack */
         andl    $-16, %esp
-#endif
     /* Branch to [caml_array_bound_error] (never returns) */
         call    G(caml_array_bound_error)
         CFI_ENDPROC

asmrun/stack.h

@@ -25,7 +25,7 @@
 
 #ifdef TARGET_i386
 #define Saved_return_address(sp) *((intnat *)((sp) - 4))
-#ifdef SYS_macosx
+#ifndef SYS_win32
 #define Callback_link(sp) ((struct caml_context *)((sp) + 16))
 #else
 #define Callback_link(sp) ((struct caml_context *)((sp) + 8))