http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56064
Bug #: 56064
Summary: Optimize VIEW_CONVERT_EXPR with FIXED_CST
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: g...@gcc.gnu.org
Created attachment 29235
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29235
foo.c.165r.expand (RTL dump)
In the followinf C code
static __inline__ __attribute__((__always_inline__))
_Fract rbits (const __INT16_TYPE__ i)
{
_Fract f;
__builtin_memcpy (&f, &i, sizeof (_Fract));
return f;
}
_Fract func (void)
{
return rbits (__INT16_C(0x1234));
}
The memcpy could be optimized away. It is represented as VIEW_CONVERT_EXPR but
FIXED_CST is not folded in fold-const.c.
The attachment shows the memory moves of HQmode which is suboptimal. For more
details, see http://gcc.gnu.org/ml/gcc/2013-01/msg00187.html
