Re: Fix gcse leak

[Richard Biener <richard dot guenther at gmail dot com>]

On May 11, 2014 3:54:30 PM CEST, Steven Bosscher <stevenb.gcc@gmail.com> wrote:
>Hello,
>
>This patch plugs a GGC leak in gcse.c, which will hold on to test insn
>to save memory. But this results in holding on to entire RTL function
>bodies, the function's CFG, and a lot more.
>
>Fix is simple: Clear the part of test_insn that causes this.
>
>Bootstrapped&tested on powerpc64-unknown-linux-gnu.
>OK for trunk?

OK.
Thanks,
Richard.


>Ciao!
>Steven
>
>
>   * gcse.c (can_assign_to_reg_without_clobbers_p): Do not let pointers
>        from test_insn into GGC space escape via SET_SRC.
>
>Index: gcse.c
>===================================================================
>--- gcse.c      (revision 209530)
>+++ gcse.c      (working copy)
>@@ -849,6 +849,7 @@ can_assign_to_reg_without_clobbers_p (rtx x)
> {
>   int num_clobbers = 0;
>   int icode;
>+  bool can_assign = false;
>
>/* If this is a valid operand, we are OK.  If it's VOIDmode, we aren't.
> */
>   if (general_operand (x, GET_MODE (x)))
>@@ -866,6 +867,7 @@ can_assign_to_reg_without_clobbers_p (rtx x)
>                                            FIRST_PSEUDO_REGISTER * 2),
>                                      const0_rtx));
>       NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
>+      INSN_LOCATION (test_insn) = UNKNOWN_LOCATION;
>     }
>
>/* Now make an insn like the one we would make when GCSE'ing and see if
>@@ -874,16 +876,19 @@ can_assign_to_reg_without_clobbers_p (rtx x)
>   SET_SRC (PATTERN (test_insn)) = x;
>
>   icode = recog (PATTERN (test_insn), test_insn, &num_clobbers);
>-  if (icode < 0)
>-    return false;
>-
>-  if (num_clobbers > 0 && added_clobbers_hard_reg_p (icode))
>-    return false;
>-
>-  if (targetm.cannot_copy_insn_p && targetm.cannot_copy_insn_p
>(test_insn))
>-    return false;
>-
>-  return true;
>+
>+  /* If the test insn is valid and doesn't need clobbers, and the
>target also
>+     has no objections, we're good.  */
>+  if (icode >= 0
>+      && (num_clobbers == 0 || !added_clobbers_hard_reg_p (icode))
>+      && ! (targetm.cannot_copy_insn_p
>+           && targetm.cannot_copy_insn_p (test_insn)))
>+    can_assign = true;
>+
>+  /* Make sure test_insn doesn't have any pointers into GC space.  */
>+  SET_SRC (PATTERN (test_insn)) = NULL_RTX;
>+
>+  return can_assign;
> }
>
>/* Return nonzero if the operands of expression X are unchanged from
>the