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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/33717] slow code generated for 64-bit arithmetic
Date: Sun, 26 Dec 2021 21:58:01 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D33717

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
GCC does better now since GCC 10:
.L2:
        movl    (%ebx,%ecx,4), %eax
        xorl    %edx, %edx
        addl    $-1, %eax
        adcl    $0, %edx
        addl    %eax, %esi
        adcl    %edx, %edi
        movl    %esi, -424(%ebp,%ecx,4)
        addl    $1, %ecx
        movl    %edi, %esi
        xorl    %edi, %edi
        cmpl    $100, %ecx
        jne     .L2

But still not as good as ICC:
..B1.4:                         # Preds ..B1.4 ..B1.3
                                # Execution count [5.00e+01]
        addl      32(%esp,%eax,8), %ebx                         #25.5
        movl      %esi, %edx                                    #25.5
        adcl      $0, %edx                                      #25.5
        addl      432(%esp,%eax,8), %ebx                        #25.37
        movl      %ebx, 832(%esp,%eax,8)                        #26.5
        movl      %esi, %ebx                                    #25.5
        adcl      $0, %edx                                      #25.37
        addl      36(%esp,%eax,8), %edx                         #25.5
        adcl      $0, %ebx                                      #25.5
        addl      436(%esp,%eax,8), %edx                        #25.37
        movl      %edx, 836(%esp,%eax,8)                        #26.5
        adcl      $0, %ebx                                      #25.37
        incl      %eax                                          #24.3
        cmpl      $50, %eax                                     #24.3
        jb        ..B1.4        # Prob 98%


LLVM just falls over:
.LBB0_1:                                # =3D>This Inner Loop Header: Depth=
=3D1
        xorl    %ebx, %ebx
        addl    808(%esp,%edx,4), %eax
        setb    %bl
        addl    408(%esp,%edx,4), %eax
        adcl    $0, %ebx
        movl    %eax, 8(%esp,%edx,4)
        cmpl    $100, %edx
        je      .LBB0_3
# %bb.2:                                #   in Loop: Header=3DBB0_1 Depth=
=3D1
        xorl    %eax, %eax
        addl    812(%esp,%edx,4), %ebx
        setb    %al
        addl    412(%esp,%edx,4), %ebx
        adcl    $0, %eax
        movl    %ebx, 12(%esp,%edx,4)
        addl    $2, %edx
        jmp     .LBB0_1
.LBB0_3:=