andy@CSVAX.CALTECH.EDU (Andy Fyfe) (02/08/89)
(gcc is configured for a sun 3 (sun os 3.5)).
Gcc botches register assignments on the following program when '-O' is used.
Without '-O', the program works ok. It seems to be necessary that the
function 'pow' be called twice with the same arguments. The use of "const"
doesn't change anything.
static inline const double
log(double x)
{
double y;
asm("flognx %1,%0": "=f" (y): "f" (x));
return y;
}
static inline const double
exp(double x) /* returns e^x */
{
double y;
asm("fetoxx %1,%0": "=f" (y): "f" (x));
return y;
}
static inline const double
pow(double x, double y) /* returns x^y */
{
return exp(y * log(x));
}
double
foo(double x, double y)
{
printf("%g\n", pow(x,y));
return pow(x,y);
}
main()
{
printf("%g\n", foo(3,2));
}
The generated assembly code follows:
#NO_APP
gcc_compiled.:
.text
LC0:
.ascii "%g\12\0"
.even
.globl _foo
_foo:
link a6,#0
fmovem #0x4,sp@-
fmoved a6@(8),fp1
#APP
flognx fp1,fp0
#NO_APP
fmuld a6@(16),fp0
#APP
fetoxx fp2,fp1 <-- should be fp0 not fp2
#NO_APP
fmoved fp1,sp@-
pea LC0
jbsr _printf
fmoved fp2,sp@- <-- should be fp1 not fp2
movel sp@+,d0
movel sp@+,d1
fmovem a6@(-12),#0x20
unlk a6
rts
.even
.globl _main
_main:
link a6,#0
clrl sp@-
movel #1073741824,sp@-
clrl sp@-
movel #1074266112,sp@-
jbsr _foo
movel d1,sp@-
movel d0,sp@-
pea LC0
jbsr _printf
unlk a6
rts