[LLVMbugs] [Bug 3829] New: Trivial piece of code misbehaves badly on FreeBSD

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=3829

           Summary: Trivial piece of code misbehaves badly on FreeBSD
           Product: clang
           Version: unspecified
          Platform: PC
        OS/Version: FreeBSD
            Status: NEW
          Severity: major
          Priority: P2
         Component: LLVM Codegen
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: ed at 80386.nl
                CC: llvmbugs at cs.uiuc.edu
            Blocks: 3696


Created an attachment (id=2720)
 --> (http://llvm.org/bugs/attachment.cgi?id=2720)
Testcase

When the attached code is compiled with Clang using -O or higher, something
strange happens. I suspect it's malloc() being called with an impossible value.

hashtabnew() when compiled with -O0:

0000000000000000 <hashtabnew>:
   0:   55                      push   %rbp
   1:   48 89 e5                mov    %rsp,%rbp
   4:   48 83 ec 30             sub    $0x30,%rsp
   8:   48 89 f0                mov    %rsi,%rax
   b:   89 f9                   mov    %edi,%ecx
   d:   89 4d f4                mov    %ecx,0xfffffffffffffff4(%rbp)
  10:   48 89 45 e8             mov    %rax,0xffffffffffffffe8(%rbp)
  14:   8b 45 f4                mov    0xfffffffffffffff4(%rbp),%eax
  17:   83 e8 01                sub    $0x1,%eax
  1a:   48 63 c0                movslq %eax,%rax
  1d:   48 b9 08 00 00 00 00    mov    $0x8,%rcx
  24:   00 00 00 
  27:   48 0f af c1             imul   %rcx,%rax
  2b:   48 89 45 d8             mov    %rax,0xffffffffffffffd8(%rbp)
  2f:   48 8b 45 d8             mov    0xffffffffffffffd8(%rbp),%rax
  33:   48 89 c7                mov    %rax,%rdi
  36:   e8 00 00 00 00          callq  3b <hashtabnew+0x3b>
  3b:   48 89 45 e0             mov    %rax,0xffffffffffffffe0(%rbp)
  3f:   48 8b 45 e0             mov    0xffffffffffffffe0(%rbp),%rax
  43:   48 8b 4d e8             mov    0xffffffffffffffe8(%rbp),%rcx
  47:   48 89 08                mov    %rcx,(%rax)
  4a:   48 8b 45 e0             mov    0xffffffffffffffe0(%rbp),%rax
  4e:   48 89 45 f8             mov    %rax,0xfffffffffffffff8(%rbp)
  52:   48 8b 45 f8             mov    0xfffffffffffffff8(%rbp),%rax
  56:   48 83 c4 30             add    $0x30,%rsp
  5a:   5d                      pop    %rbp
  5b:   c3                      retq   
  5c:   66                      data16
  5d:   66                      data16
  5e:   66                      data16
  5f:   90                      nop    

hashtabnew() when compiled with -O1:

0000000000000000 <hashtabnew>:
   0:   55                      push   %rbp
   1:   48 89 e5                mov    %rsp,%rbp
   4:   53                      push   %rbx
   5:   48 83 ec 08             sub    $0x8,%rsp
   9:   48 89 f3                mov    %rsi,%rbx
   c:   81 c7 ff ff ff 1f       add    $0x1fffffff,%edi
  12:   89 f8                   mov    %edi,%eax
  14:   48 89 c7                mov    %rax,%rdi
  17:   48 c1 e7 03             shl    $0x3,%rdi
  1b:   e8 00 00 00 00          callq  20 <hashtabnew+0x20>
  20:   48 89 18                mov    %rbx,(%rax)
  23:   48 83 c4 08             add    $0x8,%rsp
  27:   5b                      pop    %rbx
  28:   5d                      pop    %rbp
  29:   c3                      retq   
  2a:   66                      data16
  2b:   66                      data16
  2c:   90                      nop    
  2d:   66                      data16
  2e:   66                      data16
  2f:   90                      nop


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