https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79726
Bug ID: 79726
Summary: Type conversion not vectorisde
Product: gcc
Version: 7.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: drraph at gmail dot com
Target Milestone: ---
Consider:
double f(double x[]) {
float p = 1.0;
for (int i = 0; i < 16; i++)
p += x[i];
return p;
}
gcc with -O3 -march=core-avx2 -ffast-math gives:
f:
vmovsd xmm0, QWORD PTR .LC0[rip]
vaddsd xmm0, xmm0, QWORD PTR [rdi]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+8]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+16]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+24]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+32]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+40]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+48]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+56]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+64]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+72]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+80]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+88]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+96]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+104]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+112]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
vaddsd xmm0, xmm0, QWORD PTR [rdi+120]
vcvtsd2ss xmm0, xmm0, xmm0
vcvtss2sd xmm0, xmm0, xmm0
ret
.LC0:
.long 0
.long 1072693248
However more efficient would be:
f:
vcvtpd2ps xmm0, YMMWORD PTR [rdi] #4.5
vcvtpd2ps xmm1, YMMWORD PTR [32+rdi] #4.5
vcvtpd2ps xmm2, YMMWORD PTR [64+rdi] #4.5
vcvtpd2ps xmm3, YMMWORD PTR [96+rdi] #4.5
vaddps xmm4, xmm0, xmm1 #2.11
vaddps xmm5, xmm2, xmm3 #2.11
vaddps xmm6, xmm4, xmm5 #2.11
vmovhlps xmm7, xmm6, xmm6 #2.11
vaddps xmm8, xmm6, xmm7 #2.11
vshufps xmm9, xmm8, xmm8, 245 #2.11
vaddss xmm10, xmm8, xmm9 #2.11
vaddss xmm0, xmm10, DWORD PTR .L_2il0floatpacket.0[rip] #2.11
vcvtss2sd xmm0, xmm0, xmm0 #5.10
vzeroupper #5.10
ret #5.10
.L_2il0floatpacket.0:
.long 0x3f800000
