| Issue |
75592
|
| Summary |
unexpected output results in fusion using -Os
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
Elowen-jjw
|
For the following two c files, I performed the equivalent transformation of loop from **file1.c** to **file2.c**. I ran these two files respectively using different optimization levels including **-O0**, **-O1**, **-O2**, **-O3**, **-Os**, **-Ofast**. The exact output results(i.e. checksum values) are:
```
-O0 -O1 -O2 -O3 -Os -Ofast
file1.c 6BB53573 64EEDCA5 78F90205 78F90205 6BB53573 78F90205
file2.c 6BB53573 64EEDCA5 78F90205 78F90205 64EEDCA5 78F90205
```
Please help me to explain why these two files produced different output results when using the same optimization level(i.e. -Os), thank you.
command line:
```
clang <filename.c> <optimization level> -lm -I $CSMITH_HOME/include && ./a.out
```
version: clang+llvm 14.0.0
os: ubuntu 22.04
**file1.c**
```
#include "csmith.h"
static int32_t g_a96[4];
static uint64_t g_b96[4];
struct S0 {
volatile uint16_t f0;
int32_t f1;
unsigned f2 : 24;
int64_t f3;
};
struct S1 {
unsigned f0 : 6;
unsigned f1 : 5;
signed f2 : 15;
volatile uint8_t f3;
signed f4 : 12;
};
static uint64_t g_35[1][2][1] = {{{0xE3C489718B2F1036LL}, {0xE3C489718B2F1036LL}}};
static struct S1 g_46[1][2][2] = {{{{6, 2, 127, 0x92L, -50}, {6, 2, 127, 0x92L, -50}}, {{6, 2, 127, 0x92L, -50}, {6, 2, 127, 0x92L, -50}}}};
static volatile struct S0 g_53 = {0x4032L, 0xAA3630DDL, 2867, 0x930CB0470BDE7D1ELL};
static struct S0 g_72 = {1UL, 0xCEF6D7B3L, 1180, 0xCAAAB22D3B6D3E8DLL};
static struct S1 *g_200 = &g_46[0][1][1];
static struct S1 **g_199[3][3][1] = {{{&g_200}, {&g_200}, {&g_200}}, {{&g_200}, {&g_200}, {&g_200}}, {{&g_200}, {&g_200}, {&g_200}}};
static void func_1(void);
static void func_1(void) {
int32_t l_5 = 0L;
int i;
int ii_0;
// fusion
for (i = 0, ii_0 = 0; i < 3; i++, ii_0++) {
g_a96[ii_0] = g_72.f0 * l_5 + g_53.f1;
}
int jj_0;
for (jj_0 = 0; jj_0 < 4; jj_0++) {
g_b96[jj_0] = (**g_199[2][2][0]).f0 * g_a96[jj_0] + g_35[0][0][0];
}
}
int main(void) {
int i, j, k;
int print_hash_value = 0;
platform_main_begin();
crc32_gentab();
func_1();
for (i = 0; i < 1; i++) {
for (j = 0; j < 2; j++) {
for (k = 0; k < 1; k++) {
transparent_crc(g_35[i][j][k], "g_35[i][j][k]", print_hash_value);
}
}
}
for (i = 0; i < 1; i++) {
for (j = 0; j < 2; j++) {
for (k = 0; k < 2; k++) {
transparent_crc(g_46[i][j][k].f0, "g_46[i][j][k].f0", print_hash_value);
transparent_crc(g_46[i][j][k].f1, "g_46[i][j][k].f1", print_hash_value);
transparent_crc(g_46[i][j][k].f2, "g_46[i][j][k].f2", print_hash_value);
transparent_crc(g_46[i][j][k].f3, "g_46[i][j][k].f3", print_hash_value);
transparent_crc(g_46[i][j][k].f4, "g_46[i][j][k].f4", print_hash_value);
}
}
}
transparent_crc(g_53.f0, "g_53.f0", print_hash_value);
transparent_crc(g_53.f1, "g_53.f1", print_hash_value);
transparent_crc(g_53.f2, "g_53.f2", print_hash_value);
transparent_crc(g_53.f3, "g_53.f3", print_hash_value);
transparent_crc(g_72.f0, "g_72.f0", print_hash_value);
transparent_crc(g_72.f1, "g_72.f1", print_hash_value);
transparent_crc(g_72.f2, "g_72.f2", print_hash_value);
transparent_crc(g_72.f3, "g_72.f3", print_hash_value);
for (i = 0; i < 4; i++) {
transparent_crc(g_a96[i], "g_a96[i]", print_hash_value);
}
for (i = 0; i < 4; i++) {
transparent_crc(g_b96[i], "g_b96[i]", print_hash_value);
}
platform_main_end(crc32_context ^ 0xFFFFFFFFUL, print_hash_value);
return 0;
}
```
**file2.c**
```
#include "csmith.h"
static int32_t g_a96[4];
static uint64_t g_b96[4];
struct S0 {
volatile uint16_t f0;
int32_t f1;
unsigned f2 : 24;
int64_t f3;
};
struct S1 {
unsigned f0 : 6;
unsigned f1 : 5;
signed f2 : 15;
volatile uint8_t f3;
signed f4 : 12;
};
static uint64_t g_35[1][2][1] = {{{0xE3C489718B2F1036LL}, {0xE3C489718B2F1036LL}}};
static struct S1 g_46[1][2][2] = {{{{6, 2, 127, 0x92L, -50}, {6, 2, 127, 0x92L, -50}}, {{6, 2, 127, 0x92L, -50}, {6, 2, 127, 0x92L, -50}}}};
static volatile struct S0 g_53 = {0x4032L, 0xAA3630DDL, 2867, 0x930CB0470BDE7D1ELL};
static struct S0 g_72 = {1UL, 0xCEF6D7B3L, 1180, 0xCAAAB22D3B6D3E8DLL};
static struct S1 *g_200 = &g_46[0][1][1];
static struct S1 **g_199[3][3][1] = {{{&g_200}, {&g_200}, {&g_200}}, {{&g_200}, {&g_200}, {&g_200}}, {{&g_200}, {&g_200}, {&g_200}}};
static void func_1(void);
static void func_1(void) {
int32_t l_5 = 0L;
int i;
int ii_0;
int jj_0;
int ij_0;
// fusion
for (i = 0, ii_0 = 0, jj_0 = 0, ij_0 = 0; ij_0 <= 4; ij_0++) {
if (ij_0 <= 3 && i < 3) {
g_a96[ii_0] = g_72.f0 * l_5 + g_53.f1;
i++;
ii_0++;
}
if (ij_0 <= 4 && jj_0 < 4) {
g_b96[jj_0] = (**g_199[2][2][0]).f0 * g_a96[jj_0] + g_35[0][0][0];
jj_0++;
}
}
}
int main(void) {
int i, j, k;
int print_hash_value = 0;
platform_main_begin();
crc32_gentab();
func_1();
for (i = 0; i < 1; i++) {
for (j = 0; j < 2; j++) {
for (k = 0; k < 1; k++) {
transparent_crc(g_35[i][j][k], "g_35[i][j][k]", print_hash_value);
}
}
}
for (i = 0; i < 1; i++) {
for (j = 0; j < 2; j++) {
for (k = 0; k < 2; k++) {
transparent_crc(g_46[i][j][k].f0, "g_46[i][j][k].f0", print_hash_value);
transparent_crc(g_46[i][j][k].f1, "g_46[i][j][k].f1", print_hash_value);
transparent_crc(g_46[i][j][k].f2, "g_46[i][j][k].f2", print_hash_value);
transparent_crc(g_46[i][j][k].f3, "g_46[i][j][k].f3", print_hash_value);
transparent_crc(g_46[i][j][k].f4, "g_46[i][j][k].f4", print_hash_value);
}
}
}
transparent_crc(g_53.f0, "g_53.f0", print_hash_value);
transparent_crc(g_53.f1, "g_53.f1", print_hash_value);
transparent_crc(g_53.f2, "g_53.f2", print_hash_value);
transparent_crc(g_53.f3, "g_53.f3", print_hash_value);
transparent_crc(g_72.f0, "g_72.f0", print_hash_value);
transparent_crc(g_72.f1, "g_72.f1", print_hash_value);
transparent_crc(g_72.f2, "g_72.f2", print_hash_value);
transparent_crc(g_72.f3, "g_72.f3", print_hash_value);
for (i = 0; i < 4; i++) {
transparent_crc(g_a96[i], "g_a96[i]", print_hash_value);
}
for (i = 0; i < 4; i++) {
transparent_crc(g_b96[i], "g_b96[i]", print_hash_value);
}
platform_main_end(crc32_context ^ 0xFFFFFFFFUL, print_hash_value);
return 0;
}
```
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