https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68172
Bug ID: 68172
Summary: [6 Regression] LTO/PGO bootstrapped compiler is
miscompiled (looping in sched_rgn_init)
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: trippels at gcc dot gnu.org
Target Milestone: ---
Host: powerpc64le-unknown-linux-gnu
Target: powerpc64le-unknown-linux-gnu
Build: powerpc64le-unknown-linux-gnu
Created attachment 36631
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36631&action=edit
testcase
On ppc64le gcc gets miscompiled when configured and built like this:
--with-build-config="bootstrap-lto bootstrap-O3"
make profiledbootstrap
The resulting compiler loops in sched_rgn_init on the attached testcase.
% gcc -c -O3 warped_autocorrelation_FLP.i
Overhead Command Shared Object Symbol
98.23% cc1 cc1 [.] sched_rgn_init
0.10% cc1 libc-2.20.so [.] free
0.09% cc1 libc-2.20.so [.] _int_malloc
│ becomes zero. Repeat until no blocks are
left on the
│ list. This produces a topological list of
blocks in
│ the region. */
│ while (tail >= 0)
│ {
│ if (head < 0)
4.33 │ cmpwi cr5,r6,-1
│ beq- cr5,10c8b4d8 <sched_rgn_init(bool)+0x28a8>
│ head = tail;
│ child = queue[head];
10.06 │ rldicr r0,r6,2,61
47.05 │ lwax r11,r22,r0
│ if (degree[child] == 0)
│ rldicr r4,r11,2,61
1.11 │ lwzx r8,r31,r4
│ cmpwi cr7,r8,0
│ bne cr7,10c8adc0 <sched_rgn_init(bool)+0x2190>
│ {
│ edge e;
│
│ degree[child] = -1;
│ rgn_bb_table[idx++] = child;
│ lwa r16,40(r1)
