[Bug tree-optimization/72772] Missed SCEV after pass reordering@236440

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72772

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
The patch has quite some fallout, including ICEs and wrong-code :/

FAIL: c-c++-common/ubsan/pr71403-1.c   -O3 -g  execution test
FAIL: gcc.dg/graphite/pr35356-1.c scan-tree-dump graphite "if \\\\(P_9 >= P_10
\
\\\+ 1 && P_10 >= 0\\\\) \\\\{"
FAIL: gcc.dg/tree-ssa/20030714-2.c scan-tree-dump-times dom2 "if " 3
FAIL: gcc.dg/tree-ssa/ivopt_5.c scan-tree-dump-times ivopts "ivtmp.[0-9_]* =
PHI <[^0]" 0
FAIL: gcc.dg/tree-ssa/loadpre2.c scan-tree-dump-times pre "Eliminated: 1" 1
FAIL: gcc.dg/tree-ssa/loadpre21.c scan-tree-dump-times pre "Eliminated: 1" 1
FAIL: gcc.dg/tree-ssa/loadpre22.c scan-tree-dump-times pre "Eliminated: 1" 1
FAIL: gcc.dg/tree-ssa/pr21417.c scan-tree-dump-times thread4 "FSM jump thread"
1
FAIL: gcc.dg/tree-ssa/pr59597.c scan-tree-dump vrp1 "Cancelling"
FAIL: gcc.dg/tree-ssa/ssa-pre-23.c scan-tree-dump pre "Eliminated: 3"
FAIL: gcc.target/i386/pr60901.c (internal compiler error)
FAIL: gcc.target/i386/pr60901.c (test for excess errors)

and with -m32 additionally

FAIL: gcc.dg/pr45570.c (internal compiler error)
FAIL: gcc.dg/pr45570.c (test for excess errors)
FAIL: gcc.dg/pr70920-4.c scan-tree-dump forwprop1 "if \\\\(_[0-9]* == 0\\\\)"
FAIL: gcc.dg/graphite/scop-dsyr2k.c scan-tree-dump-times graphite "number of
SCoPs: 1" 1
FAIL: gcc.dg/graphite/scop-dsyrk.c scan-tree-dump-times graphite "number of
SCoPs: 1" 1
FAIL: gcc.dg/tree-ssa/pr22051-2.c scan-tree-dump-times optimized "r_. =
\\\\(int\\\\) q" 1
FAIL: gcc.dg/tree-ssa/pr71078-3.c scan-tree-dump forwprop1 "__builtin_copysign"


I fixed the PRE testcases sofar, need to investigate the above some more.

The pasted patch contained an error, the if (single_edge) condition has to be
if (nentry == 1).