[Bug c/21171] New: Generates wrong code (w/ optimization) when copying data from a table to a table in a structure
sami dot kantoluoto at embedtronics dot fi
gcc-bugzilla@gcc.gnu.org
Sat Apr 23 08:18:00 GMT 2005
Compiling the test code with optimizations enabled generates invalid code. Data
gets read from the source table but gets not written to the destination.
Test code:
/* start of test.c */
/* compile: arm-elf-gcc -Os -c -o test.o test.c */
/* dump: arm-elf-objdump -D test.o | more */
typedef unsigned int u_int32_t;
typedef unsigned char u_int8_t;
#define AIC_VECTORS 32
typedef volatile struct AT91RM9200_AIC {
u_int32_t SVR[AIC_VECTORS];
} AT91RM9200_AIC_t;
typedef volatile struct AT91RM9200_regs {
AT91RM9200_AIC_t AIC;
} AT91RM9200_regs_t;
#define CPUReg ((AT91RM9200_regs_t*)0xFFF00000)
extern const u_int32_t __IntTable[AIC_VECTORS];
int main()
{
int c;
AT91RM9200_AIC_t *aic = &CPUReg->AIC;
for (c=0; c < AIC_VECTORS; c++) {
aic->SVR[c] = __IntTable[c];
}
return 0;
}
/* end of test.c */
objdump output:
test.o: file format elf32-littlearm
Disassembly of section .text:
00000000 <main>:
0: e59f2014 ldr r2, [pc, #20] ; 1c <.text+0x1c>
4: e59f3014 ldr r3, [pc, #20] ; 20 <.text+0x20>
8: e2822004 add r2, r2, #4 ; 0x4
c: e1520003 cmp r2, r3
10: 1affffff bne 4 <main+0x4>
14: e3a00000 mov r0, #0 ; 0x0
18: e12fff1e bx lr
As you can see, there is no store (str) instruction at all. Code just goes
through the __IntTable[] but does nothing useful.
--
Summary: Generates wrong code (w/ optimization) when copying data
from a table to a table in a structure
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: critical
Priority: P1
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: sami dot kantoluoto at embedtronics dot fi
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i386-unknown-netbsdelf2.0
GCC host triplet: i386-unknown-netbsdelf2.0
GCC target triplet: arm-unknown-elf
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21171
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