http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53355
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2012-05-15
Component|middle-end |tree-optimization
AssignedTo|unassigned at gcc dot |rguenth at gcc dot gnu.org
|gnu.org |
Ever Confirmed|0 |1
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-05-15
09:40:45 UTC ---
Confirmed. Btw, it does not check for misalignment again but for whether
there is a remaining scalar iteration to be done. On trunk (for GCC 4.8)
we already improve somewhat - but the odd induction variable choices
remain.
foo:
.LFB0:
.cfi_startproc
movq %rdi, %rax
salq $60, %rax
shrq $63, %rax
testl %eax, %eax
je .L2
movsd (%rdi), %xmm0
movl $100000, %r8d
movsd .LC0(%rip), %xmm1
subl %eax, %r8d
movl %r8d, %esi
movl $99999, %r11d
addsd %xmm1, %xmm0
shrl %esi
movl %esi, %r9d
addl %r9d, %r9d
movsd %xmm0, (%rdi)
je .L9
movl $1, %r10d
.L8:
movapd .LC1(%rip), %xmm1
leaq (%rdi,%rax,8), %rcx
xorl %edx, %edx
xorl %eax, %eax
.p2align 4,,10
.p2align 3
.L7:
movapd (%rcx,%rax), %xmm0
addl $1, %edx
addpd %xmm1, %xmm0
movapd %xmm0, (%rcx,%rax)
addq $16, %rax
cmpl %esi, %edx
jb .L7
subl %r9d, %r11d
cmpl %r9d, %r8d
leal (%r10,%r9), %edx
je .L1
movsd .LC0(%rip), %xmm1
.L3:
leal -1(%r11), %ecx
movslq %edx, %rdx
leaq 0(,%rdx,8), %rax
leaq 1(%rdx,%rcx), %rdx
salq $3, %rdx
.p2align 4,,10
.p2align 3
.L6:
movsd (%rdi,%rax), %xmm0
addsd %xmm1, %xmm0
movsd %xmm0, (%rdi,%rax)
addq $8, %rax
cmpq %rdx, %rax
jne .L6
rep
ret
.L1:
ret
.L2:
movl $100000, %r8d
movl $50000, %esi
movl $100000, %r9d
movl $100000, %r11d
xorl %r10d, %r10d
jmp .L8
.L9:
movl $1, %edx
jmp .L3
what we also fail to optimize are the entry checks of the vectorized loops
after the prologue loop:
# BLOCK 2 loop_depth:0 freq:100
# PRED: ENTRY [100.0%] (fallthru,exec)
D.1738_23 = (unsigned long) x_2(D);
D.1739_24 = D.1738_23 & 15;
D.1740_25 = D.1739_24 >> 3;
D.1741_26 = -D.1740_25;
D.1742_27 = (unsigned int) D.1741_26;
D.1802_18 = D.1741_26 & 1;
prolog_loop_niters.16_28 = (unsigned int) D.1802_18;
if (prolog_loop_niters.16_28 == 0)
goto <bb 12>;
else
goto <bb 3>;
# SUCC: 3 [100.0%] (false,exec) 12 (true,exec)
# BLOCK 3 loop_depth:0 freq:100
# PRED: 2 [100.0%] (false,exec)
x_65 = x_2(D);
D.1718_37 = MEM[base: x_65, offset: 0B];
D.1719_38 = D.1718_37 + 2.0e+0;
MEM[base: x_65, offset: 0B] = D.1719_38;
prolog_loop_adjusted_niters.18_52 = D.1741_26 & 1;
niters.19_53 = 100000 - prolog_loop_niters.16_28;
bnd.20_54 = niters.19_53 >> 1;
ratio_mult_vf.21_55 = bnd.20_54 << 1;
if (ratio_mult_vf.21_55 == 0)
goto <bb 7>;
else
goto <bb 4>;
# SUCC: 4 [100.0%] (false,exec) 7 (true,exec)
we fail to see that ratio_mult_vf.21_55 is never zero. Of course that is
because of the awkward representation of the checks.
I will look into this.
