https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88882
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |wrong-debug
Status|UNCONFIRMED |NEW
Last reconfirmed| |2019-01-17
Version|unknown |9.0
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The fact that l == 2 initially has been completely elided in the IL without
retaining a # DEBUG l = NULL. CCP does this when the basic-block containing
the debug stmts is elided.
+Removing basic block 4
main ()
{
int l;
@@ -8,7 +9,6 @@
int c.1_2;
int _3;
int c.2_4;
- int _11;
<bb 2> :
# DEBUG BEGIN_STMT
@@ -19,35 +19,27 @@
if (b.0_1 != 0)
goto <bb 3>; [INV]
else
- goto <bb 4>; [INV]
+ goto <bb 5>; [INV]
<bb 4> :
# DEBUG BEGIN_STMT
- l_7 = 2;
- # DEBUG l => l_7
- # DEBUG BEGIN_STMT
- goto <bb 6>; [INV]
-
- <bb 5> :
- # DEBUG BEGIN_STMT
optimize_me_not ();
Or rather it is likely CFG cleanup which is faced with
<bb 3> :
# DEBUG BEGIN_STMT
b.0_1 = b;
if (b.0_1 != 0)
goto <bb 3>; [INV]
else
goto <bb 4>; [INV]
<bb 4> :
# DEBUG BEGIN_STMT
# DEBUG l => 2
# DEBUG BEGIN_STMT
goto <bb 6>; [INV]
<bb 6> :
c.2_4 = c;
if (c.2_4 <= 1)
goto <bb 5>; [INV]
else
goto <bb 7>; [INV]
note how it cannot move the debug stmts to neither the predecessor nor
the successor but it has to elide the forwarder for compare-debug
reasons. If we knew that l didn't have a value before we could have
moved it to the predecessor though.
Hard one.
Well - allow DEBUG stmts on edges ;)
