On 11/12/21 3:04 PM, Peter Relson wrote:
I'd think that if you want decent code, you don't ask for no optimization.
I have the following C function with embedded ASM:
int asmFunct(void *asmEntryPoint, void *functParms) {
int functRC;
__asm( " L 15,%1 \n"
" LR 1,%2 \n"
" L 1,24(1) \n"
" BALR 14,15 \n"
" ST 15,%0 "
:"=m"(functRC):"m"(asmEntryPoint), "r"(functParms)
:"r1","r14","r15");
return 0;
}
When compiled with 5650ZOS V2.3 z/OS XL C and OPT(3) it gets compiled
into a single instruction:
41F0 0000 000013 | LA r15,0
Which looks plain wrong to me.
I think it is because none of the variables referenced by the __asm
statement is reused within the function.
If I just change the return statement to look like the following:
return functRC;
The function is properly compiled into
0000DA 58F2 0000 000005 | L r15,0(r2,)
0000DE 1814 000005 | LR r1,r4
0000E0 5811 0018 000005 | L r1,24(r1,)
0000E4 05EF 000005 | BALR r14,r15
0000E6 50FD 0098 000005 | ST r15,152(r13,)
I do not have a current version at hand to see if this has been fixed.
mario
