In mesa benchmark (osmesa.c:678)
GLuint i, n, *ptr4;
n = osmesa->rowlength * osmesa->height;
ptr4 = (GLuint *) osmesa->buffer;
for (i=0;i<n;i++) {
*ptr4++ = osmesa->clearpixel;
}
The load of osmesa->clearpixel is not taken outside the loop by LIM because of
aliasing limitations. This in turn also prevents vectorization.
In this particular case we can actually get the load moved out of the loop even
without resolving the aliasing issue (which requires whole-program), on
account that even if the store aliases the load, it will not alter the value
loaded (because we store the same value that we loaded).
I'm looking into this in the context of the vectorizer.
--
Summary: Invariant load not moved out of loop
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: tree-optimization
AssignedTo: irar at il dot ibm dot com
ReportedBy: irar at il dot ibm dot com
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: powerpc-apple-darwin7.0.0
GCC host triplet: powerpc-apple-darwin7.0.0
GCC target triplet: powerpc-apple-darwin7.0.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19347
