[PATCH, rtl-optimization]: Fix PR88948, store-motion pass creates unrecognisable insn

[Uros Bizjak]

On Thu, Jan 24, 2019 at 12:52 PM Richard Sandiford
<richard.sandiford@arm.com> wrote:

> Another potential problem is that gen_move_insn should only really
> be used for general_operands.
>
> process_insert_insn seems to get this right, so it'd probably be
> cleanest to split the innards out into something that takes the dest
> and source rtxes of the move, then reuse that here.

Something like the attached patch?

2019-01-24  Uroš Bizjak  <ubizjak@gmail.com>

    PR target/88948
    * rtl.h (prepare_copy_insn): New prototype.
    * gcse.c (prepare_copy_insn): New function, split out from
    process_insert_insn.
    (process_insert_insn): Use prepare_copy_insn.
    * store-motion.c (replace_store_insn): Use prepare_copy_insn
    instead of gen_move_insn.

testsuite/ChangeLog:

2019-01-24  Uroš Bizjak  <ubizjak@gmail.com>

    PR target/88948
    * gcc.target/i386/pr88948.c: New test.

Bootstrap and regression test on x86_64-linux-gnu {,-m32} in progress.

Uros.
-------------- next part --------------
diff --git a/gcc/gcse.c b/gcc/gcse.c
index 35716cd38838..6c77671fe311 100644
--- a/gcc/gcse.c
+++ b/gcc/gcse.c
@@ -1963,14 +1963,11 @@ pre_expr_reaches_here_p (basic_block occr_bb, struct gcse_expr *expr, basic_bloc
   return rval;
 }
 

-/* Generate RTL to copy an EXPR to its `reaching_reg' and return it.  */
+/* Generate RTL to copy an EXP to REG and return it.  */
 
-static rtx_insn *
-process_insert_insn (struct gcse_expr *expr)
+rtx_insn *
+prepare_copy_insn (rtx reg, rtx exp)
 {
-  rtx reg = expr->reaching_reg;
-  /* Copy the expression to make sure we don't have any sharing issues.  */
-  rtx exp = copy_rtx (expr->expr);
   rtx_insn *pat;
 
   start_sequence ();
@@ -1996,6 +1993,18 @@ process_insert_insn (struct gcse_expr *expr)
   return pat;
 }
 
+/* Generate RTL to copy an EXPR to its `reaching_reg' and return it.  */
+
+static rtx_insn *
+process_insert_insn (struct gcse_expr *expr)
+{
+  rtx reg = expr->reaching_reg;
+  /* Copy the expression to make sure we don't have any sharing issues.  */
+  rtx exp = copy_rtx (expr->expr);
+
+  return prepare_copy_insn (reg, exp);
+}
+
 /* Add EXPR to the end of basic block BB.
 
    This is used by both the PRE and code hoisting.  */
diff --git a/gcc/rtl.h b/gcc/rtl.h
index 70891e6e3646..f99191983d39 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -4078,6 +4078,9 @@ extern void init_lower_subreg (void);
 /* In gcse.c */
 extern bool can_copy_p (machine_mode);
 extern bool can_assign_to_reg_without_clobbers_p (rtx, machine_mode);
+extern rtx_insn *prepare_copy_insn (rtx, rtx);
+
+/* In cprop.c */
 extern rtx fis_get_condition (rtx_insn *);
 
 /* In ira.c */
diff --git a/gcc/store-motion.c b/gcc/store-motion.c
index 28c4825b343d..a0838f68ba0f 100644
--- a/gcc/store-motion.c
+++ b/gcc/store-motion.c
@@ -912,8 +912,7 @@ replace_store_insn (rtx reg, rtx_insn *del, basic_block bb,
   rtx_insn *insn;
   rtx mem, note, set;
 
-  mem = smexpr->pattern;
-  insn = gen_move_insn (reg, SET_SRC (single_set (del)));
+  insn = prepare_copy_insn (reg, SET_SRC (single_set (del)));
 
   unsigned int i;
   rtx_insn *temp;
@@ -946,6 +945,7 @@ replace_store_insn (rtx reg, rtx_insn *del, basic_block bb,
   /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
      they are no longer accurate provided that they are reached by this
      definition, so drop them.  */
+  mem = smexpr->pattern;
   for (; insn != NEXT_INSN (BB_END (bb)); insn = NEXT_INSN (insn))
     if (NONDEBUG_INSN_P (insn))
       {