https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90311
Bug ID: 90311
Summary: [9/10 Regression] wrong code with -O and
__builtin_add_overflow() and compare
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: zsojka at seznam dot cz
Target Milestone: ---
Host: x86_64-pc-linux-gnu
Target: armv7a-hardfloat-linux-gnueabi
Created attachment 46274
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46274&action=edit
reduced testcase
Output:
$ armv7a-hardfloat-linux-gnueabi-gcc -O testcase.c -static
$ ./a.out
qemu: uncaught target signal 6 (Aborted) - core dumped
Aborted
Correct value is 0, wrong value is 0xffffffffffffffff
Difference between gcc-8 (OK) and gcc-9 (BAD) is:
--- testcase.s.OK 2019-05-02 12:44:11.856127737 +0200
+++ testcase.s.BAD 2019-05-02 12:44:17.306127716 +0200
@@ -27,9 +27,8 @@
movw r1, #:lower16:a
movt r1, #:upper16:a
ldrb r1, [r1] @ zero_extendqisi2
- add r1, r3, r1
- cmp r1, r3
- subcc r3, r3, #1
+ cmn r3, r1
+ sbc r3, r3, #0
str r3, [r2]
cmp r3, #0
bne .L6
$ armv7a-hardfloat-linux-gnueabi-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-armv7a-hardfloat/bin/armv7a-hardfloat-linux-gnueabi-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-270639-checking-yes-rtl-df-extra-armv7a-hardfloat/bin/../libexec/gcc/armv7a-hardfloat-linux-gnueabi/10.0.0/lto-wrapper
Target: armv7a-hardfloat-linux-gnueabi
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl --with-float=hard --with-fpu=vfpv4
--with-arch=armv7-a --with-sysroot=/usr/armv7a-hardfloat-linux-gnueabi
--build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
--target=armv7a-hardfloat-linux-gnueabi
--with-ld=/usr/bin/armv7a-hardfloat-linux-gnueabi-ld
--with-as=/usr/bin/armv7a-hardfloat-linux-gnueabi-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-270639-checking-yes-rtl-df-extra-armv7a-hardfloat
Thread model: posix
gcc version 10.0.0 20190429 (experimental) (GCC)
