Fix LRA bug

This patch fixes an ICE building libgfortran/random.c.

The problem was an adddi3 instruction that had an eliminable frame pointer.
GCN adddi3 includes a match_scratch, which LRA substitutes with a REG, and
checks if it can be converted back to a scratch afterwards.  In the meantime,
the add was converted to a move, meaning that the instruction pattern
completely changed, thus causing a segfault when the instruction is revisited
in restore_scratches.

2018-12-14  Andrew Stubbs  <ams@codesourcery.com>

	gcc/
	* gcc/lra-int.h (lra_register_new_scratch_op): Add third parameter.
	* gcc/lra-remat.c (update_scratch_ops): Pass icode to
	lra_register_new_scratch_op.
	* gcc/lra.c (struct sloc): Add icode field.
	(lra_register_new_scratch_op): Add icode parameter.
	Use icode to skip insns that have changed beyond recognition.

From-SVN: r267132

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3e3402201cdb63b7dde555a8711c42d6dafe076c..3d4a9e5f8ba307cca7421afaf0e6e079d7e14b8d 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2018-12-14  Andrew Stubbs  <ams@codesourcery.com>
+
+       * gcc/lra-int.h (lra_register_new_scratch_op): Add third parameter.
+       * gcc/lra-remat.c (update_scratch_ops): Pass icode to
+       lra_register_new_scratch_op.
+       * gcc/lra.c (struct sloc): Add icode field.
+       (lra_register_new_scratch_op): Add icode parameter.
+       Use icode to skip insns that have changed beyond recognition.
+
 2018-12-14  Eric Botcazou  <ebotcazou@adacore.com>
 
        * dwarf2out.c (analyze_discr_in_predicate): Simplify.

diff --git a/gcc/lra-int.h b/gcc/lra-int.h
index dc365d7ee69f9b222565345a41fd5e50c759ed32..6e0eb96ddf53d8d6a2f08b938665771660d036ed 100644 (file)
--- a/gcc/lra-int.h
+++ b/gcc/lra-int.h
@@ -336,7 +336,7 @@ extern void lra_create_copy (int, int, int);
 extern lra_copy_t lra_get_copy (int);
 extern bool lra_former_scratch_p (int);
 extern bool lra_former_scratch_operand_p (rtx_insn *, int);
-extern void lra_register_new_scratch_op (rtx_insn *, int);
+extern void lra_register_new_scratch_op (rtx_insn *, int, int);
 
 extern int lra_new_regno_start;
 extern int lra_constraint_new_regno_start;

diff --git a/gcc/lra-remat.c b/gcc/lra-remat.c
index faf74ca8de766f20cf028bc13aca1f6dba01fefa..627a248cf032f3f5b1b86a60ba64e38021363bf0 100644 (file)
--- a/gcc/lra-remat.c
+++ b/gcc/lra-remat.c
@@ -1042,7 +1042,7 @@ update_scratch_ops (rtx_insn *remat_insn)
            fprintf (lra_dump_file, "    Assigning the same %d to r%d\n",
                     REGNO (*loc), hard_regno);
        }
-      lra_register_new_scratch_op (remat_insn, i);
+      lra_register_new_scratch_op (remat_insn, i, id->icode);
     }
   
 }

diff --git a/gcc/lra.c b/gcc/lra.c
index 537b4ae7fa15a863502c55f5d905df4e340cbc90..ae82b608d8c012de80fee4927b0f5a99148acc6d 100644 (file)
--- a/gcc/lra.c
+++ b/gcc/lra.c
@@ -2026,6 +2026,7 @@ struct sloc
 {
   rtx_insn *insn; /* Insn where the scratch was.  */
   int nop;  /* Number of the operand which was a scratch.  */
+  int icode;  /* Original icode from which scratch was removed.  */
 };
 
 typedef struct sloc *sloc_t;
@@ -2057,7 +2058,7 @@ lra_former_scratch_operand_p (rtx_insn *insn, int nop)
 /* Register operand NOP in INSN as a former scratch.  It will be
    changed to scratch back, if it is necessary, at the LRA end.  */
 void
-lra_register_new_scratch_op (rtx_insn *insn, int nop)
+lra_register_new_scratch_op (rtx_insn *insn, int nop, int icode)
 {
   lra_insn_recog_data_t id = lra_get_insn_recog_data (insn);
   rtx op = *id->operand_loc[nop];
@@ -2065,6 +2066,7 @@ lra_register_new_scratch_op (rtx_insn *insn, int nop)
   lra_assert (REG_P (op));
   loc->insn = insn;
   loc->nop = nop;
+  loc->icode = icode;
   scratches.safe_push (loc);
   bitmap_set_bit (&scratch_bitmap, REGNO (op));
   bitmap_set_bit (&scratch_operand_bitmap,
@@ -2102,7 +2104,7 @@ remove_scratches (void)
              *id->operand_loc[i] = reg
                = lra_create_new_reg (static_id->operand[i].mode,
                                      *id->operand_loc[i], ALL_REGS, NULL);
-             lra_register_new_scratch_op (insn, i);
+             lra_register_new_scratch_op (insn, i, id->icode);
              if (lra_dump_file != NULL)
                fprintf (lra_dump_file,
                         "Removing SCRATCH in insn #%u (nop %d)\n",
@@ -2136,6 +2138,12 @@ restore_scratches (void)
          last = loc->insn;
          id = lra_get_insn_recog_data (last);
        }
+      if (loc->icode != id->icode)
+       {
+         /* The icode doesn't match, which means the insn has been modified
+            (e.g. register elimination).  The scratch cannot be restored.  */
+         continue;
+       }
       if (REG_P (*id->operand_loc[loc->nop])
          && ((regno = REGNO (*id->operand_loc[loc->nop]))
              >= FIRST_PSEUDO_REGISTER)