[llvm-bugs] [Bug 30682] New: Bogus .loc directive with -mavx

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=30682

            Bug ID: 30682
           Summary: Bogus .loc directive with -mavx
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: paul_robinson at playstation.sony.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 17431
  --> https://llvm.org/bugs/attachment.cgi?id=17431&action=edit
test case

Compiling the attached test case for X64 Linux as
   clang -c -g -S bz159663-min.cpp -mno-avx -o okay.s
and
   clang -c -g -S bz159663-min.cpp -mavx -o bad.s
and diffing the results, we see the obvious instruction differences
but also 'bad.s' has some weird stuff going on with the .loc directives.
Here's an extract from a diff, showing the assembler text generated
for source line 11 (the call to method setY):

***************
      .loc    1 11 33 is_stmt 1       # bz159663-min.cpp:11:33
      movl    -12(%rbp), %ecx
      .loc    1 11 45 is_stmt 0       # bz159663-min.cpp:11:45
      movb    %ch, %dl  # NOREX
      movzbl    %dl, %ecx  # NOREX
      .loc    1 11 32                 # bz159663-min.cpp:11:32
!     cvtsi2ssl    %ecx, %xmm0
!     .loc    1 11 8                  # bz159663-min.cpp:11:8
      movq    -24(%rbp), %rdi         # 8-byte Reload
      callq    _ZN7Vector44setYEf
---------------
      .loc    1 11 33 is_stmt 1       # bz159663-min.cpp:11:33
      movl    -12(%rbp), %ecx
      .loc    1 11 45 is_stmt 0       # bz159663-min.cpp:11:45
      movb    %ch, %dl  # NOREX
      movzbl    %dl, %ecx  # NOREX
+     .loc    1 10 32 is_stmt 1       # bz159663-min.cpp:10:32
+                                         # implicit-def: %XMM0
      .loc    1 11 32                 # bz159663-min.cpp:11:32
!     vcvtsi2ssl    %ecx, %xmm0, %xmm0
!     .loc    1 11 8 is_stmt 0        # bz159663-min.cpp:11:8
      movq    -24(%rbp), %rdi         # 8-byte Reload
      callq    _ZN7Vector44setYEf
***************

What is it about AVX that introduces the spurious directive?

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20161012/8e85364d/attachment.html>