[Bug middle-end/52861] (missed optimisation) missed transformation to memset with -O3
burnus at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Wed Apr 4 16:35:00 GMT 2012
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52861
Tobias Burnus <burnus at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
CC| |burnus at gcc dot gnu.org
Component|fortran |middle-end
--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-04-04 16:35:18 UTC ---
Regarding the first test cases:
For qq1.f, the loop remains and one gets in the loop:
MEM[base: isu_34(D), index: ivtmp.19_49, step: 4, offset: 0B] = 0;
__builtin_memcpy (D.1901_38, &" "[0], 8);
MEM[base: rsv_45(D), index: ivtmp.19_49, step: 4, offset: 0B] = 0.0;
For qq2, the first loop is replaced by:
__builtin_memset (isu_35(D), 0, D.1935_54);
__builtin_memset (rsv_38(D), 0, D.1935_54);
while for the character string, the loop is kept.
For the rather common (Fortran) case of assigning blanks (" ") to a string (cf.
also the third test case), it would be good to replace the loop
__builtin_memcpy (D.1909_46, &" "[0], 8);
by (outside the loop)
__builtin_memset (D.1909_46, " ", <array-size>*<string-length>);
More information about the Gcc-bugs
mailing list