Hi,
could a gatekeeper please help review the fix for bug963?(
https://bugs.open64.net/show_bug.cgi?id=963)
bug case:
static inline __attribute__((always_inline)) __attribute__((pure)) unsigned
char __static_cpu_has(unsigned short bit)
{
unsigned char flag;
asm volatile("1: movb $0,%0\n"
"2:\n"
".section .altinstructions,\"a\"\n"
" " ".balign 8" " " "\n"
" " ".quad" " " "1b\n"
" " ".quad" " " "3f\n"
" .word %P1\n"
" .byte 2b - 1b\n"
" .byte 4f - 3f\n"
".previous\n"
".section .discard,\"aw\",@progbits\n"
" .byte 0xff + (4f-3f) - (2b-1b)\n"
".previous\n"
".section .altinstr_replacement,\"ax\"\n"
"3: movb $1,%0\n"
"4:\n"
".previous\n"
: "=qm" (flag) : "i" (bit));
return flag;
}
unsigned char f(void){
return __static_cpu_has(24) ;
}
opencc -c bug963 <https://bugs.open64.net/show_bug.cgi?id=963>.c -O2
"bug963 <https://bugs.open64.net/show_bug.cgi?id=963>.c", line 5: Error:
Invalid 'asm' constrain : Cannot find immediate
operand for ASM
Analysis:
24 is a constant value for bit in the caller, when __static_cpu_has is
inlined to f, the bit value is failed to copy propagated into the
ASM_INPUT, this is because we now only enable var->var copy propagation for
ASM_INPUT, for the case of "i" constraint, we need do such cprop.
gcc internals
(http://gcc.gnu.org/onlinedocs/gccint/Simple-Constraints.html)
documents the "i" constraint as below, it is a target-independent
constraint.
`i' An immediate integer operand (one with constant value) is allowed. This
includes symbolic constants whose values will be known only at assembly
time or later.
suggested patch:
osprey/be/opt/opt_prop.cxx -- 966f38e..8cc897c 100644
--- a/osprey/be/opt/opt_prop.cxx
+++ b/osprey/be/opt/opt_prop.cxx
@@ -1511,6 +1511,14 @@ COPYPROP::Copy_propagate_cr(CODEREP *x, BB_NODE
*curbb,
CODEREP *possible_prop = Copy_propagate_cr(x->Opnd(i),
curbb, inside_cse, in_array);
if (possible_prop && possible_prop->Kind() ==
x->Opnd(i)->Kind())
expr = possible_prop;
+ // open64.net bug963. If the Asm_input constraint is "i",
i.e, required immediate
+ // and the possible propagation is also a var, we do this
propagation on demand.
+ else if (possible_prop &&
+ (possible_prop->Kind() == CK_CONST ||
+ possible_prop->Kind() == CK_RCONST) &&
+
!strncmp(ST_name(&St_Table[x->Asm_constraint()]),"i",1)) {
+ expr = possible_prop;
+ }
else {
x->Opnd(i)->Set_flag(CF_DONT_PROP);
expr = NULL;
Could a gatekeeper please help a review? thanks in advance.
Regards
Gang
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