------- Comment #103 from lucier at math dot purdue dot edu 2009-06-15 20:21
-------
Regarding comment #101 ...
With
heine:~/programs/gcc/objdirs/gsc-fft-tests/gambc-v4_1_2>
/pkgs/gcc-mainline/bin/gcc -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: ../../mainline/configure --prefix=/pkgs/gcc-mainline
--enable-languages=c --disable-multilib --enable-checking=release
Thread model: posix
gcc version 4.5.0 20090608 (experimental) [trunk revision 148276] (GCC)
(and including Paolo's patch to speed up DF), the routine in direct.c takes
168 ms cpu time (168 user, 0 system)
As reported here
http://www.math.purdue.edu/~lucier/bugzilla/9/
with gcc-4.2.4, this routine takes 156 ms on the same machine.
Comment #9 gives the code that 4.2.4 generates at the start of the main loop;
the start of the main loop with the version of 4.5.0 I gave above is:
.L2938:
movq %rcx, %rdx
addq 8(%rax), %rdx
leaq 4(%rcx), %rbx
movq %rdx, -8(%rax)
leaq 4(%rdx), %rdi
addq 8(%rax), %rdx
movq %rdi, -16(%rax)
movq %rdx, -24(%rax)
leaq 4(%rdx), %rdi
addq 8(%rax), %rdx
movq %rdi, -32(%rax)
movq %rdx, -40(%rax)
leaq 4(%rdx), %rdi
movq 40(%rax), %rdx
movq %rdi, -48(%rax)
movsd 7(%rdx,%rdi,2), %xmm7
movq -40(%rax), %rdi
leaq 7(%rdx,%rcx,2), %r8
addq $8, %rcx
movsd (%r8), %xmm4
cmpq %rcx, %r13
movsd 7(%rdx,%rdi,2), %xmm10
movq -32(%rax), %rdi
movsd 7(%rdx,%rdi,2), %xmm5
movq -24(%rax), %rdi
movsd 7(%rdx,%rdi,2), %xmm6
movq -16(%rax), %rdi
movsd 7(%rdx,%rdi,2), %xmm13
movq -8(%rax), %rdi
movsd 7(%rdx,%rdi,2), %xmm11
leaq (%rbx,%rbx), %rdi
movsd 7(%rdi,%rdx), %xmm9
movq 24(%rax), %rdx
movapd %xmm11, %xmm14
movsd 15(%rdx), %xmm1
movsd 7(%rdx), %xmm2
movapd %xmm1, %xmm8
movsd 31(%rdx), %xmm3
movapd %xmm2, %xmm12
mulsd %xmm10, %xmm8
mulsd %xmm7, %xmm12
mulsd %xmm2, %xmm10
mulsd %xmm1, %xmm7
movsd 23(%rdx), %xmm0
So, to my mind, this is still a 4.5 regression, as there is still a slow-down
and the code is still much less optimized by 4.5.0 than by 4.2.4. 168/156 ~
1.08, so if you want to change the Summary of this bug to 8% regression, or
some other things, that's fine, but I've changed this PR back to being a 4.5
regression.
I was not really thrilled when Richard marked PR 39157 as a duplicate of this
PR. To my mind, there are three more or less independent things---run time of
Gambit-generated code, compile time of the code, and the space required to
compile the code. This PR is about run time; PR 39157 was about space needed
by the compiler; PR 26854 is about compile time. They seem to have all been
mushed together.
--
lucier at math dot purdue dot edu changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work|4.5.0 |
Summary|[4.3/4.4 Regression] 30% |[4.3/4.4/4.5 Regression] 30%
|performance slowdown in |performance slowdown in
|floating-point code caused |floating-point code caused
|by r118475 |by r118475
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33928
