[Bug target/70302] [6 Regression] crash on valid code at -O2 and -O3 in 32-bit mode on x86_64-linux-gnu (in convert_op, at config/i386/i386.c:3414)

[ienkovich at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70302

Ilya Enkovich <ienkovich at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ienkovich at gcc dot gnu.org

--- Comment #2 from Ilya Enkovich <ienkovich at gcc dot gnu.org> ---
It is another case of uninitialized register usage.  This time uninitialized
value is used in instructions we convert.  I'm testing this patch:

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 3d8dbc4..46b410b 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -3411,8 +3411,25 @@ scalar_chain::convert_op (rtx *op, rtx_insn *insn)
     }
   else
     {
-      gcc_assert (SUBREG_P (*op));
-      gcc_assert (GET_MODE (*op) == V2DImode);
+      if (REG_P (*op))
+       {
+         /* We may have not converted register usage in case
+            this register has no definition.  Otherwise it
+            should be converted in convert_reg.  */
+         df_ref ref;
+         FOR_EACH_INSN_USE (ref, insn)
+           if (DF_REF_REGNO (ref) == REGNO (*op))
+             {
+               gcc_assert (!DF_REF_CHAIN (ref));
+               break;
+             }
+         *op = gen_rtx_SUBREG (V2DImode, *op, 0);
+       }
+      else
+       {
+         gcc_assert (SUBREG_P (*op));
+         gcc_assert (GET_MODE (*op) == V2DImode);
+       }
     }
 }