I stumbled across a code generation problem. I am still using gcc 3.3.0, so
maybe this is an old bug. Anyone care to verify this?
The problem is in the line "strgtb r2, [r0, #2]":
cmp r3, #7
strgtb r2, [r0, #2]
ble .L9
In the loop "for (r3=0; r3<8; r3++)" I expected "[r0,#2] = r2, but the condition
'gt' in 'strgtb' only stores the result when r3 > 7. It should be <=7. (Thus
strleb r2,[r0.#2] I think)
Eric.
---------------------
binutils 2.13.2.1
gcc 3.3.0
build under cygwin with
options --target=arm-ecos-elf --with-cpu=arm7tdmi --enable-languages=c,c++
---------------------
test.cpp
--------
typedef struct
{
unsigned char data;
unsigned char Reserved1;
unsigned char control;
unsigned char Reserved2;
unsigned char tb;
unsigned char Reserved3;
unsigned short X;
} StructMMIO;
void test(void)
{
int lus, lus2;
StructMMIO* Mmio = (StructMMIO*)(0xC00000);
while(1)
for (lus=0; lus<8; lus++)
Mmio->control = (1<<lus);
}
--------------------------------------------------------
arm-ecos-elf-gcc -O2 -S test.cpp
The result: test.s
----------------
.file "test.cpp"
.text
.align 2
.global _Z4testv
.type _Z4testv, %function
_Z4testv:
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
@ link register save eliminated.
@ lr needed for prologue
mov r0, #12582912
mov r1, #1
.L10:
mov r3, #0
.L9:
mov r2, r1, asl r3
add r3, r3, #1
cmp r3, #7
strgtb r2, [r0, #2]
ble .L9
b .L10
.size _Z4testv, .-_Z4testv
.ident "GCC: (GNU) 3.3"
