https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91635
Bug ID: 91635
Summary: wrong code at -O2 with __builtin_add_overflow()
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: riscv64-unknown-linux-gnu
Created attachment 46798
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46798&action=edit
reduced testcase
Output:
$ /repo/gcc-trunk/binary-latest-riscv64/bin/riscv64-unknown-linux-gnu-gcc -O2
testcase.c -static
$ qemu-riscv64 ./a.out
Aborted
At the assembly level:
foo:
# testcase.c:6: c <<= __builtin_add_overflow (-c, -1, &b);
not a0,a0 # tmp84, tmp89
lui a5,%hi(b) # tmp81,
sh a0,%lo(b)(a5) # tmp84, b
# testcase.c:9: }
li a0,0 #,
ret
Constant 0 is loaded to the register; that is wrong.
$ riscv64-unknown-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-riscv64/bin/riscv64-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-275299-checking-yes-rtl-df-extra-riscv64/bin/../libexec/gcc/riscv64-unknown-linux-gnu/10.0.0/lto-wrapper
Target: riscv64-unknown-linux-gnu
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-sysroot=/usr/riscv64-unknown-linux-gnu --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=riscv64-unknown-linux-gnu
--with-ld=/usr/bin/riscv64-unknown-linux-gnu-ld
--with-as=/usr/bin/riscv64-unknown-linux-gnu-as --disable-multilib
--disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-275299-checking-yes-rtl-df-extra-riscv64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.0.0 20190902 (experimental) (GCC)
