On Oct 21, 2011, Steve Ellcey <s...@cup.hp.com> wrote: > On Fri, 2011-10-21 at 21:25 +0200, Jakub Jelinek wrote: >> My guess would be >> http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=180194 >> DEBUG_EXPR certainly shouldn't make it through into mem_loc_descriptor, >> var-tracking is supposed to resolve that. >> >> Jakub
> You are right, the bug started at r180194. I have submitted a bug (PR > 50826) which includes a cut down test case for the problem. Thanks for testing this patch on the affected platform. I also bootstrapped it on {x86_64,i686}-linux-gnu, with and without an additional patch that looked for debug_exprs in any loc expr associated with multi-part variables. That didn't get any hits, so I ended up finding out it is the use of a pseudo to hold the internal_arg_pointer that leads to a chain of events that results in a debug temp bound to a hard reg ending up used in MEM addresses of incoming args referenced in the exprs of other debug temps. (more details in the bug report) Ok to install?
for gcc/ChangeLog from Alexandre Oliva <aol...@redhat.com> PR debug/50826 * var-tracking.c (rtx_debug_expr_p): New. (use_type): Don't use debug exprs to track non-VTA variables. Index: gcc/var-tracking.c =================================================================== --- gcc/var-tracking.c.orig 2011-10-25 02:02:25.588540417 -0200 +++ gcc/var-tracking.c 2011-10-25 02:02:29.655480746 -0200 @@ -4907,6 +4907,18 @@ replace_expr_with_values (rtx loc) return cselib_subst_to_values (loc, VOIDmode); } +/* Return true if *X is a DEBUG_EXPR. Usable as an argument to + for_each_rtx to tell whether there are any DEBUG_EXPRs within + RTX. */ + +static int +rtx_debug_expr_p (rtx *x, void *data ATTRIBUTE_UNUSED) +{ + rtx loc = *x; + + return GET_CODE (loc) == DEBUG_EXPR; +} + /* Determine what kind of micro operation to choose for a USE. Return MO_CLOBBER if no micro operation is to be generated. */ @@ -4988,7 +5000,13 @@ use_type (rtx loc, struct count_use_info else if (target_for_debug_bind (var_debug_decl (expr))) return MO_CLOBBER; else if (track_loc_p (loc, expr, INT_MEM_OFFSET (loc), - false, modep, NULL)) + false, modep, NULL) + /* Multi-part variables shouldn't refer to one-part + variable names such as VALUEs (never happens) or + DEBUG_EXPRs (only happens in the presence of debug + insns). */ + && (!MAY_HAVE_DEBUG_INSNS + || !for_each_rtx (&XEXP (loc, 0), rtx_debug_expr_p, NULL))) return MO_USE; else return MO_CLOBBER;
-- Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/ You must be the change you wish to see in the world. -- Gandhi Be Free! -- http://FSFLA.org/ FSF Latin America board member Free Software Evangelist Red Hat Brazil Compiler Engineer