https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125689
Bug ID: 125689
Summary: [16/17 Regression] [RISCV] [Miscompile] GCC -
miscompiles at -O3 since
g:699287fd7b3943ac04f78c4897a38b2170d5248e
Product: gcc
Version: 16.1.1
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 64682
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=64682&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 5. This miscompilation occurs
with optimization enabled at level -O3.
COMMANDS:
/riscv-gnu-toolchain-build/bin/riscv64-unknown-linux-gnu-gcc -march=rv64gcv -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=128,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 /riscv-gnu-toolchain-build/bin/qemu-riscv64
user-config.out 1
5
//Expected Output: 0
//Actual Output: 5
-- testcase (red.c) --
char a;
short c[8];
short d[7][17][17][17][17];
long e;
short (*f)[17][17][17][17] = d;
int printf(const char *, ...);
int main() {
for( long g=0; g<8; ++g)
c[g]=-27;
for( long g=0; g<7; ++g)
for( long i=0; i<7; ++i)
for( long j=0; j<7; ++j)
for( long k=0; k<17; ++k)
d[0][g][i][j][k] = i;
for( unsigned char m=c[1]+27; m<(e<0)+7; m+=4)
a ^= f[m][0][0][1][1];
printf("%u\n", a);
}
The issue is Found via fuzzer.
