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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug debug/105108] incomplete/incorrect DWARF information at -O1 and -Og after inlining a function returning a constant Date: Thu, 31 Mar 2022 06:39:23 +0000 [thread overview] Message-ID: <bug-105108-4-Iraqwqkh0E@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-105108-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105108 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Status|UNCONFIRMED |NEW Last reconfirmed| |2022-03-31 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- Confirmed. At -O2 we end up with int main () { <bb 2> [local count: 1073741824]: [t.c:4:2] # DEBUG BEGIN_STMT [t.c:5:2] # DEBUG BEGIN_STMT [t.c:5:8] # DEBUG l_165 => 128 [t.c:6:2] # DEBUG BEGIN_STMT [t.c:6:10] # DEBUG l_144 => 0 [t.c:7:2] # DEBUG BEGIN_STMT [t.c:7:4] a = 1; [<built-in>:0:0] return 0; } while -O1 has int main () { <bb 2> [local count: 1073741824]: [t.c:4:2] # DEBUG BEGIN_STMT [t.c:5:2] # DEBUG BEGIN_STMT [t.c:5:8] # DEBUG l_165 => 128 [t.c:6:2] # DEBUG BEGIN_STMT [t.c:7:2] # DEBUG BEGIN_STMT [t.c:7:4] a = 1; [<built-in>:0:0] return 0; with -O1 we do not inline b() but instead CCP uses value-range info to determine that l_144 cannot be 128 and thus the call to b() is DCEd before it is inlined. So indeed at -O1 we do not know the value of l_144, we only know that it cannot be 128. Not sure what we can do about the missing debug info - IIRC we cannot encode in DWARF that l_144 has the value of 'b()' (which is discovered to have no side-effects besides the return value).
next prev parent reply other threads:[~2022-03-31 6:39 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-30 14:38 [Bug debug/105108] New: " assaiante at diag dot uniroma1.it 2022-03-31 6:39 ` rguenth at gcc dot gnu.org [this message] 2022-03-31 9:20 ` [Bug debug/105108] " jakub at gcc dot gnu.org 2022-03-31 9:25 ` jakub at gcc dot gnu.org 2022-03-31 10:20 ` rguenth at gcc dot gnu.org 2022-03-31 10:32 ` jakub at gcc dot gnu.org 2022-03-31 10:36 ` jakub at gcc dot gnu.org 2022-03-31 10:41 ` jakub at gcc dot gnu.org 2022-03-31 16:55 ` assaiante at diag dot uniroma1.it 2022-03-31 16:55 ` assaiante at diag dot uniroma1.it
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