On Tue, 5 Mar 2013, Jakub Jelinek wrote:
> Hi!
>
> cselib (probably among others) isn't prepared to handle arbitrarily
> complex debug insns. The debug insns are usually created from debug stmts
> which shouldn't have unbound complexity, but with TER we can actually end up
> with arbitrarily large debug insns.
>
> This patch fixes that up during expansion, by splitting subexpressions of
> too large debug insn expressions into their own debug temporaries.
>
> So far bootstrapped/regtested on x86_64-linux and i686-linux without the
> first two hunks (it caused one failure on the latter because of invalid RTL
> sharing), I'm going to bootstrap/regtest it again, ok for trunk if it
> passes?
Works for me.
Richard.
> 2013-03-05 Jakub Jelinek <ja...@redhat.com>
>
> PR debug/56510
> * cfgexpand.c (expand_debug_parm_decl): Call copy_rtx on incoming.
> (avoid_complex_debug_insns): New function.
> (expand_debug_locations): Call it.
>
> * gcc.dg/pr56510.c: New test.
>
> --- gcc/cfgexpand.c.jj 2013-03-05 15:12:15.071565689 +0100
> +++ gcc/cfgexpand.c 2013-03-05 17:21:55.683602432 +0100
> @@ -2622,6 +2622,8 @@ expand_debug_parm_decl (tree decl)
> reg = gen_raw_REG (GET_MODE (reg), OUTGOING_REGNO (REGNO (reg)));
> incoming = replace_equiv_address_nv (incoming, reg);
> }
> + else
> + incoming = copy_rtx (incoming);
> }
> #endif
>
> @@ -2637,7 +2639,7 @@ expand_debug_parm_decl (tree decl)
> || (GET_CODE (XEXP (incoming, 0)) == PLUS
> && XEXP (XEXP (incoming, 0), 0) == virtual_incoming_args_rtx
> && CONST_INT_P (XEXP (XEXP (incoming, 0), 1)))))
> - return incoming;
> + return copy_rtx (incoming);
>
> return NULL_RTX;
> }
> @@ -3704,6 +3706,54 @@ expand_debug_source_expr (tree exp)
> return op0;
> }
>
> +/* Ensure INSN_VAR_LOCATION_LOC (insn) doesn't have unbound complexity.
> + Allow 4 levels of rtl nesting for most rtl codes, and if we see anything
> + deeper than that, create DEBUG_EXPRs and emit DEBUG_INSNs before INSN. */
> +
> +static void
> +avoid_complex_debug_insns (rtx insn, rtx *exp_p, int depth)
> +{
> + rtx exp = *exp_p;
> + if (exp == NULL_RTX)
> + return;
> + if ((OBJECT_P (exp) && !MEM_P (exp)) || GET_CODE (exp) == CLOBBER)
> + return;
> +
> + if (depth == 4)
> + {
> + /* Create DEBUG_EXPR (and DEBUG_EXPR_DECL). */
> + rtx dval = make_debug_expr_from_rtl (exp);
> +
> + /* Emit a debug bind insn before INSN. */
> + rtx bind = gen_rtx_VAR_LOCATION (GET_MODE (exp),
> + DEBUG_EXPR_TREE_DECL (dval), exp,
> + VAR_INIT_STATUS_INITIALIZED);
> +
> + emit_debug_insn_before (bind, insn);
> + *exp_p = dval;
> + return;
> + }
> +
> + const char *format_ptr = GET_RTX_FORMAT (GET_CODE (exp));
> + int i, j;
> + for (i = 0; i < GET_RTX_LENGTH (GET_CODE (exp)); i++)
> + switch (*format_ptr++)
> + {
> + case 'e':
> + avoid_complex_debug_insns (insn, &XEXP (exp, i), depth + 1);
> + break;
> +
> + case 'E':
> + case 'V':
> + for (j = 0; j < XVECLEN (exp, i); j++)
> + avoid_complex_debug_insns (insn, &XVECEXP (exp, i, j), depth + 1);
> + break;
> +
> + default:
> + break;
> + }
> +}
> +
> /* Expand the _LOCs in debug insns. We run this after expanding all
> regular insns, so that any variables referenced in the function
> will have their DECL_RTLs set. */
> @@ -3724,7 +3774,7 @@ expand_debug_locations (void)
> if (DEBUG_INSN_P (insn))
> {
> tree value = (tree)INSN_VAR_LOCATION_LOC (insn);
> - rtx val;
> + rtx val, prev_insn, insn2;
> enum machine_mode mode;
>
> if (value == NULL_TREE)
> @@ -3753,6 +3803,9 @@ expand_debug_locations (void)
> }
>
> INSN_VAR_LOCATION_LOC (insn) = val;
> + prev_insn = PREV_INSN (insn);
> + for (insn2 = insn; insn2 != prev_insn; insn2 = PREV_INSN (insn2))
> + avoid_complex_debug_insns (insn2, &INSN_VAR_LOCATION_LOC (insn2), 0);
> }
>
> flag_strict_aliasing = save_strict_alias;
> --- gcc/testsuite/gcc.dg/pr56510.c.jj 2013-03-05 16:57:54.498939220 +0100
> +++ gcc/testsuite/gcc.dg/pr56510.c 2013-03-05 16:57:54.499939214 +0100
> @@ -0,0 +1,37 @@
> +/* PR debug/56510 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -g" } */
> +
> +struct S { unsigned long s1; void **s2[0]; };
> +void **a, **b, **c, **d, **e, **f;
> +
> +static void **
> +baz (long x, long y)
> +{
> + void **s = f;
> + *f = (void **) (y << 8 | (x & 0xff));
> + f += y + 1;
> + return s;
> +}
> +
> +void bar (void);
> +void
> +foo (void)
> +{
> + void **g = b[4];
> + a = b[2];
> + b = b[1];
> + g[2] = e;
> + void **h
> + = ((void **************************)
> +
> a)[1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][66];
> + void **i = ((struct S *) h)->s2[4];
> + d = baz (4, 3);
> + d[1] = b;
> + d[2] = a;
> + d[3] = bar;
> + b = d;
> + g[1] = i[2];
> + a = g;
> + ((void (*) (void)) (i[1])) ();
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
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