[Bug c++/58372] internal compiler error: ix86_compute_frame_layout

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58372

--- Comment #15 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to David Grayson from comment #14)

> Does anyone have an idea of how to fix this bug for real?  What values
> should crtl->preferred_stack_boundary crtl->stack_alignment_needed really
> have  on Windows, and should they be controllable from the command-line? 
> Where do they get set?
> 
> --David

Reading symbols from /ssd/uros/gcc-build-xxx/gcc/cc1plus...done.
(gdb) watch x_rtl.preferred_stack_boundary 

Hardware watchpoint 1: x_rtl.preferred_stack_boundary

(gdb) r
Starting program: /ssd/uros/gcc-build-xxx/gcc/cc1plus pr58372.C
Hardware watchpoint 1: x_rtl.preferred_stack_boundary

Old value = 0
New value = 32
0x0000000000b930dc in rtl_data::init_stack_alignment (this=0x23c8ac0 <x_rtl>)
at /home/uros/gcc-svn/trunk/gcc/emit-rtl.c:6636
6636      preferred_stack_boundary = STACK_BOUNDARY;

Hardware watchpoint 1: x_rtl.preferred_stack_boundary

Old value = 32
New value = 128
emit_library_call_value_1(int, rtx_def*, rtx_def*, libcall_type, machine_mode,
int, std::pair<rtx_def*, machine_mode>*) ()
    at /home/uros/gcc-svn/trunk/gcc/calls.c:4744
4744      if (outmode != VOIDmode)

(gdb) list
4739      if (crtl->preferred_stack_boundary < PREFERRED_STACK_BOUNDARY)
4740        crtl->preferred_stack_boundary = PREFERRED_STACK_BOUNDARY;
4741
4742      /* If this kind of value comes back in memory,
4743         decide where in memory it should come back.  */
4744      if (outmode != VOIDmode)
4745        {
4746          tfom = lang_hooks.types.type_for_mode (outmode, 0);
4747          if (aggregate_value_p (tfom, 0))
4748            {

This happen when building SjLj landing pads:

#0  emit_library_call_value_1(int, rtx_def*, rtx_def*, libcall_type,
machine_mode, int, std::pair<rtx_def*, machine_mode>*)
    () at /home/uros/gcc-svn/trunk/gcc/calls.c:4744
#1  0x0000000000b9b36c in emit_library_call (arg1_mode=<optimized out>,
arg1=<optimized out>, outmode=E_VOIDmode, 
    fn_type=LCT_NORMAL, fun=<optimized out>) at
/home/uros/gcc-svn/trunk/gcc/rtl.h:4123
#2  sjlj_emit_function_enter(rtx_code_label*) () at
/home/uros/gcc-svn/trunk/gcc/except.c:1202
#3  0x0000000000b9f20a in sjlj_build_landing_pads () at
/home/uros/gcc-svn/trunk/gcc/except.c:1481
#4  finish_eh_generation() () at /home/uros/gcc-svn/trunk/gcc/except.c:1510

Adding -mpreferred-stack-boundary=2 "fixes" compilation.

If you want to experiment, try the following patch:

Index: config/i386/mingw32.h
===================================================================
--- config/i386/mingw32.h       (revision 265582)
+++ config/i386/mingw32.h       (working copy)
@@ -251,6 +251,10 @@
 #undef  CHECK_EXECUTE_STACK_ENABLED
 #define CHECK_EXECUTE_STACK_ENABLED flag_setstackexecutable

+#undef PREFERRED_STACK_BOUNDARY_DEFAULT
+#define PREFERRED_STACK_BOUNDARY_DEFAULT       \
+  (TARGET_64BIT ? 128 : MIN_STACK_BOUNDARY)
+
 /* This matches SHLIB_SONAME and SHLIB_SOVERSION in t-cygming. */
 /* This matches SHLIB_SONAME and SHLIB_SOVERSION in t-cygwin. */
 #if DWARF2_UNWIND_INFO

But I don't know the details of MS ABI, so I can't tell if the patch is
correct.