https://llvm.org/bugs/show_bug.cgi?id=30375
Bug ID: 30375 Summary: Regression in Clang-4.0.0's optimizer Product: new-bugs Version: trunk Hardware: PC OS: Linux Status: NEW Severity: normal Priority: P Component: new bugs Assignee: unassignedb...@nondot.org Reporter: ishiura-compi...@ml.kwansei.ac.jp CC: llvm-bugs@lists.llvm.org Classification: Unclassified We compiled a program (A.c) by clang-4.0.0 and clang-3.6.2 with -O3 option. clang-3.6.2 performed better optimization than clang-4.0.0. (A.c) int x0 = 1; int main () { int x1 = 1; int t0 = 2 / ((1 / x0) && x1); if (t0 != 2) __builtin_abort(); return 0; } +-------------------------------+--------------------------------+ |clang-4.0.0.s |clang-3.6.2.s | |(clang-4.0.0 A.c -O3 -S) |(clang-3.6.2 A.c -O3 -S) | +-------------------------------+--------------------------------+ |main: |main: | | .cfi_startproc | .cfi_startproc | |# BB#0: |# BB#0: | | movl x0(%rip), %eax | | | leal 1(%rax), %ecx | | | cmpl $3, %ecx | | | sbbb %cl, %cl | | | testl %eax, %eax | | | setne %al | | | andb %cl, %al | | | movzbl %al, %ecx | | | movl $2, %eax | | | xorl %edx, %edx | | | divl %ecx | | | cmpl $2, %eax | | | jne .LBB0_2 | | |# BB#1: | | | xorl %eax, %eax | xorl %eax, %eax | | retq | retq | |.LBB0_2: | | | pushq %rax | | |.Ltmp0: |.Ltmp0: | | .cfi_def_cfa_offset 16 | .size main, .Ltmp0-...| | callq abort | | |.Lfunc_end0: | | | .size main, .Lfunc...| | | .cfi_endproc | .cfi_endproc | | | | | .type x0,@object | .type x0,@object | | .data | .data | | .globl x0 | .globl x0 | | .p2align 2 | .align 4 | |x0: |x0: | | .long 1 | .long 1 | | .size x0, 4 | .size x0, 4 | | | | | | | | .ident "clang versi...| .ident "Ubuntu clang...| | .section ".no...| .section ".not...| +-------------------------------+--------------------------------+ using built-in specs. clang version 4.0.0 (https://github.com/llvm-mirror/clang.git 359c45534e46a8ef263db1a8b855740bbeca6998) (https://github.com/llvm-mirror/llvm.git 990fea5450379639c1e21f456d44a9e95eabaff3) Target: x86_64-unknown-linux-gnu Thread model: posix InstalledDir: /usr/local/bin Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5 Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.2.1 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.4 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.2.1 Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.2.1 Candidate multilib: .;@m64 Candidate multilib: 32;@m32 Candidate multilib: x32;@mx32 Selected multilib: .;@m64 using built-in specs. Ubuntu clang version 3.6.2-1 (tags/RELEASE_362/final) (based on LLVM 3.6.2) Target: x86_64-pc-linux-gnu Thread model: posix Found candidate GCC installation: /usr/bin/../lib/gcc/i686-linux-gnu/5.2.1 Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.7 Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.7.4 Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8 Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8.5 Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9 Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9.3 Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5.2.1 Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.2.1 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.4 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3 Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.2.1 Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5.2.1 Candidate multilib: .;@m64 Candidate multilib: 32;@m32 Candidate multilib: x32;@mx32 Selected multilib: .;@m64 -- You are receiving this mail because: You are on the CC list for the bug.
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