https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87188
Bug ID: 87188
Summary: Function pointer canonicalization optimized away
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: danglin at gcc dot gnu.org
Target Milestone: ---
Host: hppa*-*-* (32-bit)
Target: hppa*-*-* (32-bit)
Build: hppa*-*-* (32-bit)
Created attachment 44647
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44647&action=edit
c++ testcase
This is debian bug #907586 reported by Mattias Ellert:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=907586
Compilation is as follows:
g++ -O2 -g -c -o main.o main.cpp
g++ -O2 -g -fPIC -c -o S.o S.cpp
g++ -shared -fPIC -o libS.so S.o
g++ -o main main.o -L. -lS
g++ -o altmain main.o S.o
-- Running using shared library
LD_LIBRARY_PATH=. ./main
not OK
-- Running using static build
./altmain
OK
If S.cpp is compiled at -O0, the test passes.
The problem in the optimized code is here:
.align 4
.LC0:
.word P%_ZNK2SVneERKS_
.text
.align 4
.globl _ZNK2SR4findEv
.type _ZNK2SR4findEv, @function
.LFB1721:
.cfi_startproc
_ZNK2SR4findEv:
.PROC
.CALLINFO FRAME=0,NO_CALLS
.ENTRY
ldw 0(%r26),%r21
comb,=,n %r26,%r21,.L14
ldw 12(%r21),%r20
ldw 8(%r21),%r28
addil LT'.LC0,%r19
ldw RT'.LC0(%r1),%r31
ldw 0(%r31),%r22
comclr,<> %r22,%r28,%r28
ldi 1,%r28
The comclr instruction compares the function pointer at .LC0 with the one
indirectly passed via this.
The code needs to call __canonicalize_funcptr_for_compare().
