On Mon, Dec 14, 2009 at 3:50 PM, Martin Reinecke <mar...@mpa-garching.mpg.de> wrote: > Hi, > > I have noticed a big performance decrease in one of my numerical codes > when switching from gcc 4.4 to gcc 4.5. A small test case is attached. > When compiling this test case with "gcc -O3 perf.c -lm -std=c99" > and executing the resulting binary, the CPU time with the head of > the 4.4 branch is about 1.1s, with the head of the trunk it is 2.1s. > > This is on a Pentium D CPU. I have verified that both binaries produce > identical results. > > If I can do anything to help locate the reason for this slowdown, I'd be > glad to help, but I must admit that I'm no good at interpreting assembler. > > Any insight would be greatly appreciated. >
You didn't what target you are using. Pentium D can run both 32bit and 64bit. codes. -- H.J.
