From: Pavel Labath <pavel@labath.sk>
Date: Mon, 23 Dec 2019 13:33:00 +0000 (+0100)
Subject: [lldb/DWARF] Fix hostname-stripping logic
X-Git-Tag: llvmorg-11-init~1492
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=46f02fc922e053006e34d860e9efaf29c88d8ba3;p=platform%2Fupstream%2Fllvm.git

[lldb/DWARF] Fix hostname-stripping logic

This bit of code is trying to strip everything up to the first colon
from all debug info paths, as dwarf2 recommends this syntax for storing
the compilation host name. However, this code was too eager, and it
ended up stripping the entire compilation directory, if it did not
contain a forward slash (or a "x:\").

Normally this does not matter, as all absolute paths will contain one of
these patterns, but this does not have to be the case in case the debug
info is produced by "clang -fdebug-compilation-dir", which can end up
producing a relative compilation directory with no slashes (this is one
of the techniques for producing "relocatable" debug info).
---

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
index fde6459..3ced8d7 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -718,6 +718,8 @@ FileSpec DWARFUnit::GetFile(size_t file_idx) {
 // Remove the host part if present.
 static llvm::StringRef
 removeHostnameFromPathname(llvm::StringRef path_from_dwarf) {
+  if (!path_from_dwarf.contains(':'))
+    return path_from_dwarf;
   llvm::StringRef host, path;
   std::tie(host, path) = path_from_dwarf.split(':');
 
diff --git a/lldb/test/Shell/SymbolFile/DWARF/debug_line-relative_path.s b/lldb/test/Shell/SymbolFile/DWARF/debug_line-relative_path.s
new file mode 100644
index 0000000..8bbf30b
--- /dev/null
+++ b/lldb/test/Shell/SymbolFile/DWARF/debug_line-relative_path.s
@@ -0,0 +1,49 @@
+# This tests handling of debug info with fully relative paths, such as those
+# produced by "clang -fdebug-compilation-dir <something-relative>". This is one
+# of the techniques used to produce "relocatable" debug info.
+
+# REQUIRES: x86
+
+# RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux -o %t %s
+# RUN: %lldb %t -o "image dump line-table t.c" | FileCheck %s
+
+# CHECK: 0x0000000000000000: {{q[\\/]w[\\/]e[\\/]r[\\/]t}}.c:1
+
+        .text
+main:
+        .file   1 "w/e/r" "t.c"
+        .loc    1 1 0                   # w/e/r/t.c:1:0
+        retq
+
+        .section        .debug_abbrev,"",@progbits
+        .byte   1                       # Abbreviation Code
+        .byte   17                      # DW_TAG_compile_unit
+        .byte   0                       # DW_CHILDREN_no
+        .byte   37                      # DW_AT_producer
+        .byte   8                       # DW_FORM_string
+        .byte   3                       # DW_AT_name
+        .byte   8                       # DW_FORM_string
+        .byte   16                      # DW_AT_stmt_list
+        .byte   23                      # DW_FORM_sec_offset
+        .byte   27                      # DW_AT_comp_dir
+        .byte   8                       # DW_FORM_string
+        .byte   0                       # EOM(1)
+        .byte   0                       # EOM(2)
+        .byte   0                       # EOM(3)
+
+        .section        .debug_info,"",@progbits
+.Lcu_begin0:
+        .long   .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
+.Ldebug_info_start0:
+        .short  4                       # DWARF version number
+        .long   .debug_abbrev           # Offset Into Abbrev. Section
+        .byte   8                       # Address Size (in bytes)
+        .byte   1                       # Abbrev [1] 0xb:0x40 DW_TAG_compile_unit
+        .asciz  "Hand-written DWARF"    # DW_AT_producer
+        .asciz  "w/e/r/t.c"             # DW_AT_name
+        .long   .Lline_table_start0     # DW_AT_stmt_list
+        .asciz  "q"                     # DW_AT_comp_dir
+.Ldebug_info_end0:
+
+        .section        .debug_line,"",@progbits
+.Lline_table_start0: