https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115462
Hu Lin <lin1.hu at intel dot com> changed:
What |Removed |Added
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CC| |lin1.hu at intel dot com
--- Comment #3 from Hu Lin <lin1.hu at intel dot com> ---
I looked up the hotspot for this test.
At int2a.F:570 (we output its .f file int2a.fppized.f.), its source code is
566 DO 200 K = 1,MAX
567 MX = NX+KLX(K)
568 MY = NY+KLY(K)
569 MZ = NZ+KLZ(K)
570 N = N1+KLGT(K)
571 200 GHONDO(N) = ( XIN(MX )*YIN(MY )*ZIN(MZ ) +XIN(MX+625)*YIN(MY+625)*
572 + ZIN(MZ+625) +XIN(MX+1250)*YIN(MY+1250)*ZIN(MZ+1250) )*D1*
573 + DKL(K)+GHONDO(N)
.
At this loop's beginning, the original ASM code is
mov 0x271e3c98(,%rdx,4),%edi
mov 0x271e401c(,%rdx,4),%esi
mov 0x271e43a0(,%rdx,4),%ecx
mov 0x271e3914(,%rdx,4),%r8d
.
But after r15-882-g1d6199e5f8c1c0, the ASM code is
mov $0x27bf6c98, %r10d
mov $0x27bf701c, %r9d
mov $0x27bf73a0, %esi
movl (%rbx,%rdx,4), %ecx
movl (%r10,%rdx,4), %edi
movl (%r9,%rdx,4), %r8d
movl (%rsi,%rdx,4), %esi
.
In addition to this loop other places also have some similar extra
instructions. These instructions increase the instruction retired by about the
similar percentage as the regression.
