--- Ian Lance Taylor <iant@xxxxxxxxxx> wrote: > ranjith kumar <ranjit_kumar_b4u@xxxxxxxxxxx> writes: > > > 1) In my P.C. gcc version 4.1.2 has been > installed. > > I have a look at http://gcc.gnu.org/. > > In that it is said that 4.1.2 is the "current > > release series", "Next release series: GCC 4.2.0" > and > > "Active development: GCC 4.3.0" > > > > What does it mean? Has gcc 4.2.0/4.3.0 been > > released??? > > No. It means that 4.2 is the next release. 4.3 is > under active > development. > > > > 2)From which version "auto-vectorization" has been > > included? > > In > > > http://gcc.gnu.org/projects/tree-ssa/vectorization.html#status4.0 > > it is said that gcc 4.0 also does > > "auto-vectorization". > > Deos it mean auto-vectorization cababilities of > gcc4.0 > > and gcc4.1/4.2 are same?? > > No, it is under active development and is enhanced > in each release. > > > 3)-ftree-vectorize is the flag that enables > > autovectorization. isn't it?? > > Yes. > > > 4) where can I get C programs for which gcc can do > > autovectorization and for which it cant? > > There are test cases in gcc/testsuite/gcc.dg/vect. What does auto-vectorization mean?? I think it must be converting 'for' loops which does not exploit SIMD features of a processor(say Pentium 4) to 'for' loops which exploit SIMD features(of course, it could be at any intermediate representation). I have taken vect-40.c in that directory and compiled as "gcc -march=pentium4 -S -O3 -ftree-vectorize vect-40.c". I looked at the assembly code. No MMX/SSE/SSE2 instructions were there. (I have gcc-4.1.2 installed in my P.C. and my processor is Pentium4.) What can gcc do? Can it produce MMX/SSE/SSE2 instructions even if the source file(.c) does not use any functions defined in mmintrin.h/xmmintrin.h/emmintrin.h???? If so, did I miss any other option while compiling? Thanks in advance. > > > 4) I know all languages are internallay converted > to > > same representation(in the context of gcc > compiler). > > So what is said in gcc manuals about > > auto-vectorization is applicable to all languages > gcc > > supports. Isn't it? > > Yes. But some languages are more amenable to > vectorization than > others. > > Ian > ___________________________________________________________ Now you can scan emails quickly with a reading pane. Get the new Yahoo! Mail. http://uk.docs.yahoo.com/nowyoucan.html
