When compiling the following code with m68k-elf-gcc and optimization
-O, the compiler does not generate code to increment the stack pointer
before restoring %fp and returning from the function. This happens in
both functions, f1 and f2. I checked with gcc-3.3 and gcc-3.4.3. When
using no optimization (no -O), this error doesn't happen. When using
-O3, the code in f1 is correct but in f2 is wrong.
Code:
struct Value
{
char type;
int val;
};
extern struct Value f3(int x);
int f2(int a, int b, int c)
{
return f3(c).val;;
}
int f1(int nValue)
{
return f2(0, 0, nValue);
}
Compilation command line:
m68k-elf-gcc -O -Wall -c -m68000 -o test.o test.c
Compiler output:
<none>
Resulting code:
00000000 <f2>:
0: 4e56 fff8 linkw %fp,#-8
4: 2f2e 0010 movel %fp@(16),[EMAIL PROTECTED]
8: 41ee fffa lea %fp@(-6),%a0
c: 4eb9 0000 0000 jsr 0 <f2>
12: 202e fffc movel %fp@(-4),%d0
16: 4e5e unlk %fp
18: 4e75 rts
0000001a <f1>:
1a: 4e56 0000 linkw %fp,#0
1e: 2f2e 0008 movel %fp@(8),[EMAIL PROTECTED]
22: 42a7 clrl [EMAIL PROTECTED]
24: 42a7 clrl [EMAIL PROTECTED]
26: 61d8 bsrs 0 <f2>
28: 4e5e unlk %fp
2a: 4e75 rts
Error analysis:
Before address 16 in <f2> there is missing a
addq #4,%sp
and before address 28 in <f1> there is missing a
lea %sp@(12),%sp
The GCCs I used are cross compilers for m68k-elf compiled on an
i686 host. The source was downloaded from an ftp.gnu.org mirror, no
patches applied, locally configured and compiled under cygwin.
GCC-3.3:
$ m68k-elf-gcc -v
Reading specs from /tools/H-i686-pc-cygwin/lib/gcc-lib/m68k-elf/3.3/specs
Configured with: /src/gcc-3.3/configure --target=m68k-elf
--prefix=/tools/H-i686-pc-cygwin --enable-shared --enable-languages=c
--with-gnu-as --with-gnu-ld --with-newlib -v
Thread model: single
gcc version 3.3
GCC-3.4.3:
Reading specs from /tools/H-i686-pc-cygwin/lib/gcc/m68k-elf/3.3/specs
Configured with: /src/gcc-3.4.3/configure
--with-gcc-version-trigger=/src/gcc-3.3/gcc/version.c --host=i686-pc-cygwin
--target=m68k-elf --prefix=/tools/H-i686-pc-cygwin --enable-shared
--enable-languages=c --with-cpu-68000 --with-gnu-as --with-gnu-ld --with-newlib
-v
Thread model: single
gcc version 3.4.3
--
Summary: Stack pointer error after call to function returning a
struct
Product: gcc
Version: 3.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: keller at fs-net dot de
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i686-pc-cygwin
GCC host triplet: i686-pc-cygwin
GCC target triplet: m68k-elf
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21152
