Compiling the code:
extern void doSomething(unsigned v);
void irq_() __attribute__ ((interrupt("IRQ")));
void irq_()
{
unsigned v;
doSomething(v);
}
with:
arm-elf-g++ -O0\
-fno-exceptions\
-fomit-frame-pointer\
-S -o irq-bug.s\
irq-bug.cc
results in:
.file "irq-bug.cc"
.text
.align 2
.global _Z4irq_v
.type _Z4irq_v, %function
_Z4irq_v:
@ Interrupt Service Routine.
@ args = 0, pretend = 0, frame = 4
@ frame_needed = 0, uses_anonymous_args = 0
sub lr, lr, #4 @<------------------- (1)
stmfd sp!, {r0, r1, r2, r3, ip, lr}
sub sp, sp, #4
ldr r0, [sp, #0]
bl _Z11doSomethingj
add sp, sp, #4
ldmfd sp!, {r0, r1, r2, r3, ip, lr}
subs pc, lr, #4 @<------------------- (2)
.size _Z4irq_v, .-_Z4irq_v
.ident "GCC: (GNU) 4.1.1"
Remarks:
- the lr register is decremented twice (1) (2)
- the -O0 and -fomit-frame-pointer switches are relevant
- arm-elf-g++ -v:
Using built-in specs.
Target: arm-elf
Configured with:
/home/buchmann/devel/gcc/dist/gcc-4.1.1/configure -v
--prefix=/home/buchmann/devel/gcc/targets/arm/
--target=arm-elf --enable-languages=c,c++,java
--disable-threads
--disable-shared
--disable-multilib
--with-as=/home/buchmann/devel/gcc/targets/arm/arm-elf/bin/as
--with-ld=/home/buchmann/devel/gcc/targets/arm/arm-elf/bin/ld
--with-newlib
--without-headers
Thread model: single
gcc version 4.1.1
Best regards
Hans Buchmann
--
Summary: Wrong Code for ARM IRQ routine
Product: gcc
Version: 4.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: hans dot buchmann at fhso dot ch
GCC build triplet: i386-pc-linux-gnu
GCC host triplet: i386-pc-linux-gnu
GCC target triplet: arm-elf
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29004
