I'm working on an updated version of my translation validator [*], and I
have some problems with CLOBBER(eol).
I currently treat CLOBBER(eol) as making the memory invalid (i.e. all
subsequent accesses is undefined behavior), but the tool reports
miscompilation for a few cases where the tree-nrv pass makes the IR
clobber <retval> by changing code such as [**]
union bu o;
...
o = i;
MEM[(union *)&o].b18 = _11;
MEM[(union *)&o].b20 = _11;
<retval> = o;
o ={v} {CLOBBER(eol)};
return <retval>;
to use <retval> instead of o
union bu o [value-expr: <retval>];
...
<retval> = i;
MEM[(union *)&<retval>].b18 = _11;
MEM[(union *)&<retval>].b20 = _11;
<retval> ={v} {CLOBBER(eol)};
return <retval>;
As a result, the tool therefore thinks the returned value is unavailable.
Is my understanding of CLOBBER(eol) correct? (I.e., is this a bug in
tree-nrv?) Or is <retval> special so that I should just ignore
CLOBBER(eol) for this case?
/Krister
[*] I'm planning to release the updated version in a few weeks. Meanwhile,
you can find the old version at https://github.com/kristerw/pysmtgcc
[**] This example originates from gcc.c-torture/execute/921204-1.c
compiled for x86 using the flags "-O -m32".
