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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/109724] [10 regression] Huge memory usage when building
 qtwebengine's SkOpAngle.cpp since r10-11201-g051f78a5c1d699
Date: Thu, 04 May 2023 07:14:25 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109724

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
The real issue is probably that when value-numbering

Value numbering stmt =3D iftmp.77_74 =3D PHI <iftmp.77_178(64), iftmp.77_17=
7(65)>
Setting value number of iftmp.77_74 to iftmp.77_177 (changed)
iftmp.77_177 is available for iftmp.77_177

we have _177 available but for

Value numbering stmt =3D _24 =3D &MEM <const struct SkDCubic> [(const struct
SkDPoint &)iftmp.77_74].fPts[idx2_62].fX;
Setting value number of _24 to iftmp.77_177 (changed)
Making available beyond BB70 _24 for value iftmp.77_177

we appearantly have not, despite the _74 def dominating this stmt.  Of cour=
se
that's an inherent limitation of the dominated_by_p_w_unex tool that was
patched with the offending revision.=