https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125516
Bug ID: 125516
Summary: [16/17 Regression] [RISCV] [Miscompile] GCC
miscompiles at -O3 as well as -O2 since
g:573ea59a48d95fc4e9f520865eae71c5d9de614f
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: skothadiya at whileone dot in
Target Milestone: ---
Created attachment 64591
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=64591&action=edit
Attached reduced testcase
Description:
The testcase code involves for loops on various datatypes, compiles correctly
on x86_64 and produces the expected output. However, when compiled for the
riscv64 architecture, the resulting binary yields an incorrect value. The
expected output is 0, but the program returns 17. This miscompilation occurs
with optimization enabled at level -O3 & -O2.
COMMANDS:
/riscv-gnu-toolchain-build/bin/riscv64-unknown-linux-gnu-gcc
-march=rv64gcv_zvl256b -flto -O3 red.c -o user-config.out -fsigned-char
-fno-strict-aliasing -fwrapv -Wno-unknown-warning-option -Werror -Wfatal-errors
-Wall -Wformat -Wno-int-in-bool-context -Wno-dangling-pointer
-Wno-compare-distinct-pointer-types -Wno-overflow -Wuninitialized
-Warray-bounds -Wreturn-type -Wno-unused-function -Wno-unused-variable
-Wno-unused-but-set-variable -Wno-unused-value -Wno-address -Wno-bool-compare
-Wno-pointer-sign -Wno-bool-operation -Wno-tautological-compare
-Wno-self-assign -Wno-implicit-const-int-float-conversion
-Wno-constant-conversion -Wno-unused-value
-Wno-tautological-constant-out-of-range-compare -Wno-constant-logical-operand
-Wno-parentheses-equality -Wno-pointer-sign
QEMU_CPU=rv64,vlen=256,rvv_ta_all_1s=true,rvv_ma_all_1s=true,v=true,vext_spec=v1.0,zve32f=true,zve64f=true
timeout --verbose -k 0.1 4
/mnt/data1/sujayk/cifuzz-pad/riscv-gnu-toolchain-build/bin/qemu-riscv64
user-config.out 1
17
//Expected Output: 0
//Actual Output: 17
-- testcase (red.c) --
char a;
long long b;
short d[18][18][18][18];
short (*e)[18][18][18] = d;
int printf(const char *, ...);
int main() {
for (long h=0; h<4; ++h)
for (long i=0; i<18; ++i)
for (long j=0; j<18; ++j)
for (long k=0; k<18; ++k)
d[h][i][j][k] = j;
for (short i= 0; i< 8; i++)
for (unsigned char j= 0; j< 18; j++)
a = e[3][i][i][j] ? e[j][i][i][3] : 0;
b = (int)a;
printf("%llu\n", b);
}
The issue is Found via fuzzer.
