Re: [Tinycc-devel] Assertion `(v >= TREG_XMM0) && (v <= TREG_XMM7)' failed

[Michael Matz]

Hi,

On Mon, 31 Mar 2014, Thomas Preudhomme wrote:

> Le 2014-03-31 22:36, Jay Foad a écrit :
> > Hi,
> >
> > I get an assertion failure on this small test case:
> >
> > $ cat f.c
> > struct s { double a, b; } z;
> > struct s f() { return 0 ? z : 0; }
> > $ ./tcc f.c
> > tcc: x86_64-gen.c:494: load: Assertion `(v >= TREG_XMM0) && (v <=
> > TREG_XMM7)' failed.
> > Aborted (core dumped)
> 
> Must be me in fdb3b10d0693cf33ce5a0acf17f0f323d79ee5f1.

No no, not your fault.  It's a pre-existing problem of not being able to 
correctly load a multi-reg structure that's a temporary result from the 
conditional operator.  Actually with this testcase tcc has two bugs.  The 
testcase as above is invalid C, both arms of the cond-expression must be 
the same type.  But even with this fixed it's not working:

$ cat f2.c
struct s { double a, b; } z;
struct s f(int c) { return c ? z : (struct s){0.0,0.0}; }

Something is either wrong with evaluating the cond-expr: vtop is the 
address of the relevant structure in reg, but not marked specially.  
Somehow the lvalue-ness/address-ness goes lost in the expansion of the 
cond-expression.


Ciao,
Michael.