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* [Bug middle-end/82325] worse code generated compared to clang when using a constexpr array
[not found] <bug-82325-4@http.gcc.gnu.org/bugzilla/>
@ 2023-01-19 4:24 ` pinskia at gcc dot gnu.org
0 siblings, 0 replies; only message in thread
From: pinskia at gcc dot gnu.org @ 2023-01-19 4:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82325
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|c++ |middle-end
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note clang 15+ no longer unrolls the loop and even produces really bad code for
the loop now:
.LBB0_7: # in Loop: Header=BB0_1 Depth=1
addq $2, %rdx
.LBB0_1: # =>This Inner Loop Header: Depth=1
movzwl -4(%rax,%rdx,4), %esi
cmpl %edi, %esi
jg .LBB0_3
# %bb.2: # in Loop: Header=BB0_1 Depth=1
movzbl -2(%rax,%rdx,4), %ecx
movl $1, %r8d
shll %cl, %r8d
addl %esi, %r8d
cmpl %edi, %r8d
jg .LBB0_8
.LBB0_3: # in Loop: Header=BB0_1 Depth=1
cmpq $29, %rdx
je .LBB0_4
# %bb.5: # in Loop: Header=BB0_1 Depth=1
movzwl (%rax,%rdx,4), %esi
cmpl %edi, %esi
jg .LBB0_7
# %bb.6: # in Loop: Header=BB0_1 Depth=1
movzbl 2(%rax,%rdx,4), %ecx
movl $1, %r8d
shll %cl, %r8d
addl %esi, %r8d
cmpl %edi, %r8d
jle .LBB0_7
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2023-01-19 4:24 ` [Bug middle-end/82325] worse code generated compared to clang when using a constexpr array pinskia at gcc dot gnu.org
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