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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug debug/54953] New: [4.8 Regression] New sra-1.c FAILs on powerpc Date: Wed, 17 Oct 2012 15:59:00 -0000 [thread overview] Message-ID: <bug-54953-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54953 Bug #: 54953 Summary: [4.8 Regression] New sra-1.c FAILs on powerpc Classification: Unclassified Product: gcc Version: 4.8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: debug AssignedTo: unassigned@gcc.gnu.org ReportedBy: jakub@gcc.gnu.org CC: aoliva@gcc.gnu.org Target: powerpc64-linux When backporting the valtrack.c addition and related changes to 4.7 branch, I've noticed it regresses some sra-1.c tests that used to pass, in particular FAIL: gcc.dg/guality/sra-1.c -O1 line 43 a.i == 4 (ditto for all other > -O1 levels). The problem is that before fwprop1 we have: (insn 11 10 12 2 (set (reg:HI 130 [ a$i ]) (asm_operands:HI ("") ("=r") 0 [ (reg:HI 131) ] [ (asm_input:HI ("0") (null):0) ] [] sra-1.c:40)) sra-1.c:40 -1 (nil)) (insn 12 11 13 2 (set (reg:DI 127 [ a$i+-6 ]) (sign_extend:DI (reg:HI 130 [ a$i ]))) sra-1.c:40 21 {*rs6000.md:447} (nil)) (debug_insn 13 12 14 2 (var_location:HI a$i (subreg:HI (reg:DI 127 [ a$i+-6 ]) 6)) sra-1.c:40 -1 (nil)) and reg:HI 130 is really dead, and fwprop1 decides to propagate into the debug_insn, so after fwprop1 debug_insn 13 contains (reg:HI 130) instead of the subreg. Then cprop1 comes and performs fast DCE, which decides to put a debug temp for reg:HI 130 using DEBUG_TEMP_BEFORE_WITH_VALUE before the asm instruction, but obviously asm_operands inside of var_location is never going to expand to anything useful. dce.c seems to be the only user of DEBUG_TEMP_BEFORE_WITH_VALUE mode of insertion. If the insn it is adding it to is not marked (!marked_insn_p (insn)), then that is certainly the right thing to do, the insn is going to be removed and we have no other option. But if it is being kept, just debug temp is being added because of debug uses after the pseudo became dead, then this is counterproductive.
next reply other threads:[~2012-10-17 15:59 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-10-17 15:59 jakub at gcc dot gnu.org [this message] 2012-10-17 16:04 ` [Bug debug/54953] " jakub at gcc dot gnu.org 2012-10-26 7:42 ` aoliva at gcc dot gnu.org 2012-10-26 8:29 ` jakub at gcc dot gnu.org 2012-10-30 8:08 ` jakub at gcc dot gnu.org 2012-11-07 11:41 ` jakub at gcc dot gnu.org
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