configure: Use -mpreferred-stack-boundary=2 on i386.

gcc currently assumes the stack alignment for i686-w64-mingw32 is 16, which is essentially wrong. It works around this in most cases by applying -mstackrealign when SSE is in use. However, this doesn't address the case of manually aligned types (i.e. DECLSPEC_ALIGN), and it also for some reason doesn't seem to apply when -mavx512f is in use, which seems to be an independent gcc bug. The correct solution on the gcc end is not to assume that the stack is 4-byte aligned. -mpreferred-stack-boundary=2 achieves exactly this, and there is motion upstream to address this by effectively making this setting the default. Since this will take time to propagate downstream, though, it seems prudent to address this bug locally by essentially applying the same fix downstream. Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55007 Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55899

configure: Use -mpreferred-stack-boundary=2 on i386.
4b458775 · Zebediah Figura · Alexandre Julliard · 3545c35d · 4b458775 · 4b458775
Commit 4b458775 authored Sep 21, 2023 by Zebediah Figura Committed by Alexandre Julliard Dec 07, 2023
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configure configure +34 -0

configure.ac configure.ac +1 -0

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--- a/configure
+++ b/configure
@@ -11551,6 +11551,40 @@ if eval test \"x\$"$as_ac_var"\" = x"yes"
 then :
  as_fn_append ${wine_arch}_EXTRACFLAGS " -fno-omit-frame-pointer"
 fi }
+            { as_ac_var=`printf "%s\n" "ac_cv_${wine_arch}_cflags_-mpreferred-stack-boundary=2" | $as_tr_sh`
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -mpreferred-stack-boundary=2" >&5
+printf %s "checking whether $CC supports -mpreferred-stack-boundary=2... " >&6; }
+if eval test \${$as_ac_var+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+  ac_wine_try_cflags_saved=$CFLAGS
+ac_wine_try_cflags_saved_exeext=$ac_exeext
+CFLAGS="$CFLAGS -nostdlib -nodefaultlibs -mpreferred-stack-boundary=2"
+ac_exeext=".exe"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void *__os_arm64x_dispatch_ret = 0;
+int __cdecl mainCRTStartup(void) { return 0; }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  eval "$as_ac_var=yes"
+else $as_nop
+  eval "$as_ac_var=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+CFLAGS=$ac_wine_try_cflags_saved
+ac_exeext=$ac_wine_try_cflags_saved_exeext
+fi
+eval ac_res=\$$as_ac_var
+	       { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+printf "%s\n" "$ac_res" >&6; }
+if eval test \"x\$"$as_ac_var"\" = x"yes"
+then :
+  as_fn_append ${wine_arch}_EXTRACFLAGS " -mpreferred-stack-boundary=2"
+fi }
            { as_ac_var=`printf "%s\n" "ac_cv_${wine_arch}_cflags_-Wl,--disable-stdcall-fixup" | $as_tr_sh`
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether $CC supports -Wl,--disable-stdcall-fixup" >&5
 printf %s "checking whether $CC supports -Wl,--disable-stdcall-fixup... " >&6; }

--- a/configure.ac
+++ b/configure.ac
@@ -991,6 +991,7 @@ This is an error since --enable-archs=$wine_arch was requested.])])

    case $wine_arch in
      i386) WINE_TRY_PE_CFLAGS([-fno-omit-frame-pointer])
+            WINE_TRY_PE_CFLAGS([-mpreferred-stack-boundary=2])
            WINE_TRY_PE_CFLAGS([-Wl,--disable-stdcall-fixup],
                               [AS_VAR_APPEND([${wine_arch}_LDFLAGS],[" -Wl,--disable-stdcall-fixup"])]) ;;
      x86_64) WINE_TRY_PE_CFLAGS([-Wformat-overflow])