[llvm-bugs] [Bug 36493] New: clang windows is emitting column information

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=36493

            Bug ID: 36493
           Summary: clang windows is emitting column information
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: DebugInfo
          Assignee: unassignedbugs at nondot.org
          Reporter: zturner at google.com
                CC: llvm-bugs at lists.llvm.org

In theory, CodeView supports column information.  However, most windows
debuggers don't recognize it and -- worse -- behave incorrectly in the presence
of column information.  If you compile this program with clang on Windows:

  int f(int, int);
# 1 "F:\\git\\fastbuild\\Code\\Tools\\FBuild\\FBuildApp\\Main.cpp"
int g;
int i() {
  # 83
  return f(g, g);
}

it will generate LLVM assembly that looks like this:

        .cv_loc 0 1 83 15               #
F:\git\fastbuild\Code\Tools\FBuild\FBuildApp\Main.cpp:83:15
        movl    "?g@@3HA", %eax
        .cv_loc 0 1 83 12               #
F:\git\fastbuild\Code\Tools\FBuild\FBuildApp\Main.cpp:83:12
        movl    "?g@@3HA", %ecx
        .cv_loc 0 1 83 10               #
F:\git\fastbuild\Code\Tools\FBuild\FBuildApp\Main.cpp:83:10
        movl    %ecx, (%esp)

What this is trying to say is that there are 3 different addresses for line 83,
corresponding to columns 10, 12, and 15 respectively.  But the debugger simply
interprets this as "there are 3 addresses for line 83", and as a result you
have to hit the step button 3 times to get to the next statement.

This seems like a regression, as I don't recall us emitting this before.  At
the very least, the debugger was working on step over before as far as I
remember.

We will need to stop emitting cv_loc directives at column granularity.  Note
that -dwarf-column-info was not passed on the command line here.  The arguments
used were:

    r"d:\src\llvmbuild\cl\Release\x64\bin\clang++.exe",
    "-std=c++11",
    r"Main.cpp",
    "-c",
    "-g3",
    "-gcodeview",
    "-Wall",
    "-Werror",
    "-Wfatal-errors",
    "-Wextra",
    "-DWIN32_LEAN_AND_MEAN",
    "-D_WIN32",
    "-D__WINDOWS__",
    "-DWIN32",
    "-D_CRT_SECURE_NO_WARNINGS",
    "-D_WINSOCK_DEPRECATED_NO_WARNINGS",
    "-m32",
    "-D_X86_=1",
    "-D_INTEGRAL_MAX_BITS=64",
    "-D_MT",
    "-fms-compatibility",
    "-fms-extensions",
    "-fmsc-version=1900",
    "-Wno-#pragma-messages",
    "-Wno-unknown-pragmas",
    "-Wno-unused-function",
    "-Wno-microsoft",
    "-Wno-unused-value",
    "-Wno-ignored-attributes",
    "-Wno-incompatible-ms-struct",
    "-Wno-nonportable-include-path",
    "-Wno-ignored-pragma-intrinsic",
    "-Wno-invalid-token-paste",
    "-Wno-implicit-exception-spec-mismatch",
    "-Wshadow",
    "-fno-rtti",
    "-Xclang",
    "-flto-visibility-public-std",
    "-DDEBUG",
    "-DPROFILING_ENABLED",
    "-O0",
    "-S"]

-- 
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/20180223/f208326c/attachment.html>