Hi,
I have a new fix for the bug787, the cut-down case from Rao(thanks) is as
follows:
extern int main(int argc)
{
int res1;
int val0,val1;
val1=100;
if(1)
{
asm("bswapl %0" : "=r" (val0) : "0" (val1));
res1=val0;
}
val0=res1;
asm("bswapl %0" : "=r" (val1) : "0" (val0));
} /* main */
analysis:
Current open64 disallows copy propagation into ASM_INPUT for the var and
ivar cases, this is reasonable since some constraints do only allow the
parameter in specific form.
If we fix following Rao's suggested way, i.e, mark some identity assignment
undeletable for DCE, then we need special marking work for the identity
assignment.
a sound way as RAO suggested is say if the LHS of the identity assignment
has flag CR_DONT_PROP, we disable deleting this identiy assign. However,
this triggers the problem that other identity assign also undeletable only
if its LHS has CR_DONT_PROP, so bug882 thrown out and it is hard to patch
again for this special handling, this changes the default verifycation
and DCE behavior.
My suggested way is that we try propagate to a var inside ASM_INPUT, if the
propagated expr is also a var, we allow this propagation. in the above case
>LINE 13___
> LDID I4 I4 sym5v3 0 ty=402 <u=2 cr13> flags:0x8 b=-1 #res1
>OPR_STID I4 I4 sym4v4 0 <u=0 cr15> b=-1 flags:0x2 pj2 Sid-1
chi <> 0x0x80e1e40
>LINE 14___
mu<9/cr14 >
> LDID I4 I4 sym4v4 0 ty=402 <u=0 cr15> flags:0x0 b=-1 #val0
> ASM_INPUT opnd:1 <u=0 cr16> isop_flags:0xc0000 flags:0x0 b=E1
> ASM_STMT <u=0 cr17> isop_flags:0xc0000 flags:0x0 b=-1
>OPR_ASM_STMT b=-1 flags:0x2 pj2 Sid-1
sym5v3 is propagated into OPR_ASMINPUT.
The patch below:
--- a/osprey/be/opt/opt_prop.cxx
+++ b/osprey/be/opt/opt_prop.cxx
@@ -1504,9 +1504,23 @@ COPYPROP::Copy_propagate_cr(CODEREP *x, BB_NODE
*curbb,
expr = Copy_propagate_cr(x->Opnd(i), curbb, inside_cse, in_array);
else {
// OSP_384
- if(opr == OPR_ASM_INPUT)
- x->Opnd(i)->Set_flag(CF_DONT_PROP);
- expr = NULL;
+ if(opr == OPR_ASM_INPUT) {
+ // open64.net bug787. Try propagate for VAR first, if the
propagated expr is the same
+ // kind to the original one,i.e, also a VAR. we allow this
propagation. otherwise, disable it.
+ if ( x->Opnd(i)->Kind() == CK_VAR ) {
+ 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;
+ else {
+ x->Opnd(i)->Set_flag(CF_DONT_PROP);
+ expr = NULL;
+ }
+ }
+ else {
+ x->Opnd(i)->Set_flag(CF_DONT_PROP);
+ expr = NULL;
+ }
+ }
}
#else
please gatekeeper help a review
Thanks.
Regards
Gang
------------------------------------------------------------------------------
Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex
infrastructure or vast IT resources to deliver seamless, secure access to
virtual desktops. With this all-in-one solution, easily deploy virtual
desktops for less than the cost of PCs and save 60% on VDI infrastructure
costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox
_______________________________________________
Open64-devel mailing list
Open64-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/open64-devel
