[lldb][ELF] Read symbols from .gnu_debugdata sect.

Summary:
If the .symtab section is stripped from the binary it might be that
there's a .gnu_debugdata section which contains a smaller .symtab in
order to provide enough information to create a backtrace with function
names or to set and hit a breakpoint on a function name.

This change looks for a .gnu_debugdata section in the ELF object file.
The .gnu_debugdata section contains a xz-compressed ELF file with a
.symtab section inside. Symbols from that compressed .symtab section
are merged with the main object file's .dynsym symbols (if any).
In addition we always load the .dynsym even if there's a .symtab
section.

For example, the Fedora and RHEL operating systems strip their binaries
but keep a .gnu_debugdata section. While gdb already can read this
section, LLDB until this patch couldn't. To test this patch on a
Fedora or RHEL operating system, try to set a breakpoint on the "help"
symbol in the "zip" binary. Before this patch, only GDB can set this
breakpoint; now LLDB also can do so without installing extra debug
symbols:

    lldb /usr/bin/zip -b -o "b help" -o "r" -o "bt" -- -h

The above line runs LLDB in batch mode and on the "/usr/bin/zip -h"
target:

    (lldb) target create "/usr/bin/zip"
    Current executable set to '/usr/bin/zip' (x86_64).
    (lldb) settings set -- target.run-args  "-h"

Before the program starts, we set a breakpoint on the "help" symbol:

    (lldb) b help
    Breakpoint 1: where = zip`help, address = 0x00000000004093b0

Once the program is run and has hit the breakpoint we ask for a
backtrace:

    (lldb) r
    Process 10073 stopped
    * thread #1, name = 'zip', stop reason = breakpoint 1.1
        frame #0: 0x00000000004093b0 zip`help
    zip`help:
    ->  0x4093b0 <+0>:  pushq  %r12
        0x4093b2 <+2>:  movq   0x2af5f(%rip), %rsi       ;  + 4056
        0x4093b9 <+9>:  movl   $0x1, %edi
        0x4093be <+14>: xorl   %eax, %eax

    Process 10073 launched: '/usr/bin/zip' (x86_64)
    (lldb) bt
    * thread #1, name = 'zip', stop reason = breakpoint 1.1
      * frame #0: 0x00000000004093b0 zip`help
        frame #1: 0x0000000000403970 zip`main + 3248
        frame #2: 0x00007ffff7d8bf33 libc.so.6`__libc_start_main + 243
        frame #3: 0x0000000000408cee zip`_start + 46

In order to support the .gnu_debugdata section, one has to have LZMA
development headers installed. The CMake section, that controls this
part looks for the LZMA headers and enables .gnu_debugdata support by
default if they are found; otherwise or if explicitly requested, the
minidebuginfo support is disabled.

GDB supports the "mini debuginfo" section .gnu_debugdata since v7.6
(2013).

Reviewers: espindola, labath, jankratochvil, alexshap

Reviewed By: labath

Subscribers: rnkovacs, wuzish, shafik, emaste, mgorny, arichardson, hiraditya, MaskRay, lldb-commits

Tags: #lldb, #llvm

Differential Revision: https://reviews.llvm.org/D66791

llvm-svn: 373891

lldb/cmake/modules/LLDBConfig.cmake

@@ -1,5 +1,6 @@
 include(CheckCXXSymbolExists)
 include(CheckTypeSize)
+include(CMakeDependentOption)
 
 set(LLDB_PROJECT_ROOT ${CMAKE_CURRENT_SOURCE_DIR})
 set(LLDB_SOURCE_ROOT "${CMAKE_CURRENT_SOURCE_DIR}/source")
@@ -384,6 +385,13 @@ endif()
 set(LLDB_VERSION "${LLDB_VERSION_MAJOR}.${LLDB_VERSION_MINOR}.${LLDB_VERSION_PATCH}${LLDB_VERSION_SUFFIX}")
 message(STATUS "LLDB version: ${LLDB_VERSION}")
 
+find_package(LibLZMA)
+cmake_dependent_option(LLDB_ENABLE_LZMA "Support LZMA compression" ON "LIBLZMA_FOUND" OFF)
+if (LLDB_ENABLE_LZMA)
+  include_directories(${LIBLZMA_INCLUDE_DIRS})
+endif()
+llvm_canonicalize_cmake_booleans(LLDB_ENABLE_LZMA)
+
 include_directories(BEFORE
   ${CMAKE_CURRENT_BINARY_DIR}/include
   ${CMAKE_CURRENT_SOURCE_DIR}/include

lldb/include/lldb/Host/Config.h.cmake

@@ -35,4 +35,6 @@
 #cmakedefine HAVE_LIBCOMPRESSION
 #endif
 
+#cmakedefine01 LLDB_ENABLE_LZMA
+
 #endif // #ifndef LLDB_HOST_CONFIG_H

lldb/include/lldb/Host/LZMA.h

@@ -0,0 +1,34 @@
+//===-- LZMA.h --------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef liblldb_Host_LZMA_h_
+#define liblldb_Host_LZMA_h_
+
+#include "llvm/ADT/ArrayRef.h"
+
+namespace llvm {
+class Error;
+} // End of namespace llvm
+
+namespace lldb_private {
+
+namespace lzma {
+
+bool isAvailable();
+
+llvm::Expected<uint64_t>
+getUncompressedSize(llvm::ArrayRef<uint8_t> InputBuffer);
+
+llvm::Error uncompress(llvm::ArrayRef<uint8_t> InputBuffer,
+                       llvm::SmallVectorImpl<uint8_t> &Uncompressed);
+
+} // End of namespace lzma
+
+} // End of namespace lldb_private
+
+#endif // liblldb_Host_LZMA_h_

lldb/lit/CMakeLists.txt

@@ -56,9 +56,11 @@ list(APPEND LLDB_TEST_DEPS
   lli
   llvm-config
   llvm-dwarfdump
+  llvm-nm
   llvm-mc
   llvm-objcopy
   llvm-readobj
+  llvm-strip
   )
 
 if(TARGET lld)

lldb/lit/Modules/ELF/Inputs/minidebuginfo-main.c

@@ -0,0 +1,12 @@
+// This function will be embedded within the .symtab section of the
+// .gnu_debugdata section.
+int multiplyByFour(int num) { return num * 4; }
+
+// This function will be embedded within the .dynsym section of the main binary.
+int multiplyByThree(int num) { return num * 3; }
+
+int main(int argc, char *argv[]) {
+  int x = multiplyByThree(argc);
+  int y = multiplyByFour(x);
+  return y;
+}

lldb/lit/Modules/ELF/minidebuginfo-corrupt-xz.yaml

@@ -0,0 +1,29 @@
+# REQUIRES: lzma
+
+# This test checks that an error occurs when a corrupted
+# .gnu_debugdata section is trying to be xz uncompressed.
+
+# RUN: yaml2obj %s > %t.obj
+
+# TODO(kwk): once yaml2obj doesn't auto-generate a .symtab section
+# when there's none in YAML, remove the following line:
+
+# RUN: llvm-objcopy --remove-section=.symtab %t.obj
+
+# RUN: %lldb -b -o 'image dump symtab' %t.obj 2>&1 | FileCheck %s
+
+# CHECK: warning: (x86_64) {{.*}}.obj An error occurred while decompression the section .gnu_debugdata: lzma_stream_buffer_decode()=lzma error: LZMA_DATA_ERROR
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+  Entry:           0x00000000004004C0
+Sections:
+  - Name:            .gnu_debugdata
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content:         FD377A585A000004E6D6B4460200210116000000742FE5A3E0180F05BA5D003F914584683D89A6DA8ACC93E24ED90802EC1FE2A7102958F4A42B6A7134F23922F6F35F529E133A8B5588025CFAC876C68510A157DBBCF8CA75E9854DED10FDD5CE0CDC136F6459B13B9847AEF79E9B1C7CD70EF4F3AF709F5DA0C1F40780154D72120A6A62A3F1A216E20DC597CE55BB23B48785957321A15FEE48808C1428B925DBC8022541CC594BD0AF2B51C6BE2854C81611017704DF6E509D21013B80BEC27D8919ACD3157E89353A08F4C86781ED708E89AB322D010F0F1605DAD9B9CE2B13C387769C83F5F85C647FD9C551E0E9C7D4A5CBE297970E486CB94AC283F98A7C6412A57F9C37952327549EEC4634D2CFA55B0F99923A14992D4293E0D87CEEF7FB6160C45928DE25074EEBF5329B5579AF01DB23DF22CBD48C8037B68FFFBE5CEA6CD26A936DD07D9B2E6006B7C6E5CC751072185EFE995D3F3C8DACF9039D4BEFB1F376B491568F6F00DB50FF477F36B90413E4FA30AE7C561A1249FD45FDFF884F70247FC21E57195A764151D8E341267E724D856C512BD243CDB33AB313758443877B2CB58F7F8F0461DE9766647F333A3531BDC4A26E9537EB314708D31212FCF4C21E9CB139F4DBFD21BB16A126C35E2BB3F7E30BF5A54961CECD4DD4D91A3757356F618754B21533C34F2BD97D70A02B1F338588BDBA9CDF5FC9FBE973E550194F07EC7A1E8E3C005FD60F8853223427628987E82E701CA7E2FDFA1B0ED564C37D115A72C3EC01E29C85C3630D8A385C4AE12F4F75F9F0BC12F2698345DD62A1F546A5953AF5CF3C0F22C7DA510F6739EB8CDB0E8A5A3BC13CFC31C1875C313908EFF23678869B76A6E1C10FE699E43BFFDE8F0752ED994A4A84BC0AD9D7381131D457C4917C4F6656F5C95D3221A79166C802D5F5A7C68554E54C42CA535465D224C7B641CF3417C3EAFD03CE5709BEA33DC7C9155CAC9D3C8033AF7CDA622020606A7C139D77FF85BC19323BF956C9C4662F60079BC7FE5F67B46211716A1A6CE4AB8AAB307D6444310CBC101071703EECC0B4622D91D705F5DA2932DA8BCEDA8E1CB0CDB20AAD652B8F86A521D3421287F1C175AE3BE6458AE6F8F3FB6FB7ED97B616B580D791E5FE0B74973F8604F419039B5B9D9A14397EE509F2B33AE404FF96DD0551472C5302E67910F0794B15CFE837351C6AF89B2FE88488B557BE8ACFFA331FB7AD553D35CAEB7D8BCEFB6CFF4A58E91355FE931408CF4CAFA9B97518B9E5C02078F64CE81279801B090348213DCAA7D12DC098BFF58C5A3202EFC38F64AD894379747B54AB5A9843F82E5FF1F394C8B78344A8F1655DDEF8D5FE09EBB3E703853ABD716743507000696FB6B35216B088E499F53880375521442ED45DCDD1B31AAEBDAD3C7DA958593425206C4B2A0BC6CADE3B0B1598499E08016E84F33E3EB9D7B03B9C9DFA91B8CE5C74DEF2BC97FEE9982B0AEC16C75EEB7AE9A858A9C37F6C12B040C68A49111DCF0F3A4780F3879E93D904676BE908FDC66373D34AA715A39EFBC2795C6C8F058CA24392FB2591AD06ACD6AED8746F926886180C2B007ED58C9884A8BEF6CCA1F549F5C4FB411A3FF78770D1147363AC80B98B5A8FDB3DEC4E61709F66A622BDA835B1FD67B7C7CB166ABB163FB7C5204AE200C71C6A18B532C407647323B8F2FAC7ECB68C250877FC8DD5FE05B2B39E66F687EBB6EEFB7D5209E22F451B76F57D90BB6641DFFDE1A1821C4D783E4756F3CEE7F63B9BA284F8E114B0D9A086D83233BED4A8F5B60933DC16AF4DDE19C9FC59BCC1646343ECE7007B1C4DC65C4A939CDD47F6ED8855913183149BECE66D8FE7793AE607EB8E28513749B9548252764110D3B58D1D8B348DB18F7F24F8CA0C7D9CB515D90F7F1848FF58472B2EF52EBAB123AFC7F87890CE9FC55B31160014294A9B7F81638A27335E29E15A10B1068D5E049B1C239814DBBCC1BB30E11EEBAD5ACF8FB1B986C4F48D73FEA6129D9708A0B5AC435402BEC8C79C71DB94394811B9A604141A125A4669F9A139A0264E93E822117BE8E0D93A1487C51214E9FBF5763A3FBE9DA700B9C9B435472AF9F0B4446B000000003239307DD8B645100001D60B90300000CA1EC9E9B1C467FB020000000004595A
+...

lldb/lit/Modules/ELF/minidebuginfo-find-symbols.yaml

@@ -0,0 +1,26 @@
+# REQUIRES: lzma
+
+# RUN: yaml2obj %s > %t.obj
+
+# TODO(kwk): once yaml2obj doesn't auto-generate a .symtab section
+# when there's none in YAML, remove the following line:
+
+# RUN: llvm-objcopy --remove-section=.symtab %t.obj
+
+# RUN: %lldb -b -o 'image dump symtab' %t.obj | FileCheck %s
+
+# CHECK: [ 0] 1 X Code 0x00000000004005b0 0x000000000000000f 0x00000012 multiplyByFour
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+  Entry:           0x00000000004004C0
+Sections:
+  - Name:            .gnu_debugdata
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content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
+...

lldb/lit/Modules/ELF/minidebuginfo-no-lzma.yaml

@@ -0,0 +1,29 @@
+# REQUIRES: !lzma
+
+# This test checks that a warning is printed when we're trying
+# to decompress a .gnu_debugdata section when no LZMA support was compiled in.
+
+# RUN: yaml2obj %s > %t.obj
+
+# TODO(kwk): once yaml2obj doesn't auto-generate a .symtab section
+# when there's none in YAML, remove the following line:
+
+# RUN: llvm-objcopy --remove-section=.symtab %t.obj
+
+# RUN: %lldb -b -o 'image dump symtab' %t.obj 2>&1 | FileCheck %s
+
+# CHECK: warning: (x86_64) {{.*}}.obj No LZMA support found for reading .gnu_debugdata section
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+  Entry:           0x00000000004004C0
+Sections:
+  - Name:            .gnu_debugdata
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content:         FD377A585A000004E6D6B4460200210116000000742FE5A3E0180F05BA5D003F914584683D89A6DA8ACC93E24ED90802EC1FE2A7102958F4A42B6A7134F23922F6F35F529E133A8B5588025CFAC876C68510A157DBBCF8CA75E9854DED10FDD5CE0CDC136F6459B13B9847AEF79E9B1C7CD70EF4F3AF709F5DA0C1F40780154D72120A6A62A3F1A216E20DC597CE55BB23B48785957321A15FEE48808C1428B925DBC8022541CC594BD0AF2B51C6BE2854C81611017704DF6E509D21013B80BEC27D8919ACD3157E89353A08F4C86781ED708E89AB322D010F0F1605DAD9B9CE2B13C387769C83F5F85C647FD9C551E0E9C7D4A5CBE297970E486CB94AC283F98A7C6412A57F9C37952327549EEC4634D2CFA55B0F99923A14992D4293E0D87CEEF7FB6160C45928DE25074EEBF5329B5579AF01DB23DF22CBD48C8037B68FFFBE5CEA6CD26A936DD07D9B2E6006B7C6E5CC751072185EFE995D3F3C8DACF9039D4BEFB1F376B491568F6F00DB50FF477F36B90413E4FA30AE7C561A1249FD45FDFF884F70247FC21E57195A764151D8E341267E724D856C512BD243CDB33AB313758443877B2CB58F7F8F0461DE9766647F333A3531BDC4A26E9537EB314708D31212FCF4C21E9CB139F4DBFD21BB16A126C35E2BB3F7E30BF5A54961CECD4DD4D91A3757356F618754B21533C34F2BD97D70A02B1F338588BDBA9CDF5FC9FBE973E550194F07EC7A1E8E3C005FD60F8853223427628987E82E701CA7E2FDFA1B0ED564C37D115A72C3EC01E29C85C3630D8A385C4AE12F4F75F9F0BC12F2698345DD62A1F546A5953AF5CF3C0F22C7DA510F6739EB8CDB0E8A5A3BC13CFC31C1875C313908EFF23678869B76A6E1C10FE699E43BFFDE8F0752ED994A4A84BC0AD9D7381131D457C4917C4F6656F5C95D3221A79166C802D5F5A7C68554E54C42CA535465D224C7B641CF3417C3EAFD03CE5709BEA33DC7C9155CAC9D3C8033AF7CDA622020606A7C139D77FF85BC19323BF956C9C4662F60079BC7FE5F67B46211716A1A6CE4AB8AAB307D6444310CBC101071703EECC0B4622D91D705F5DA2932DA8BCEDA8E1CB0CDB20AAD652B8F86A521D3421287F1C175AE3BE6458AE6F8F3FB6FB7ED97B616B580D791E5FE0B74973F8604F419039B5B9D9A14397EE509F2B33AE404FF96DD0551472C5302E67910F0794B15CFE837351C6AF89B2FE88488B557BE8ACFFA331FB7AD553D35CAEB7D8BCEFB6CFF4A58E91355FE931408CF4CAFA9B97518B9E5C02078F64CE81279801B090348213DCAA7D12DC098BFF58C5A3202EFC38F64AD894379747B54AB5A9843F82E5FF1F394C8B783C3A8F1655DDEF8D5FE09EBB3E703853ABD716743507000696FB6B35216B088E499F53880375521442ED45DCDD1B31AAEBDAD3C7DA958593425206C4B2A0BC6CADE3B0B1598499E08016E84F33E3EB9D7B03B9C9DFA91B8CE5C74DEF2BC97FEE9982B0AEC16C75EEB7AE9A858A9C37F6C12B040C68A49111DCF0F3A4780F3879E93D904676BE908FDC66373D34AA715A39EFBC2795C6C8F058CA24392FB2591AD06ACD6AED8746F926886180C2B007ED58C9884A8BEF6CCA1F549F5C4FB411A3FF78770D1147363AC80B98B5A8FDB3DEC4E61709F66A622BDA835B1FD67B7C7CB166ABB163FB7C5204AE200C71C6A18B532C407647323B8F2FAC7ECB68C250877FC8DD5FE05B2B39E66F687EBB6EEFB7D5209E22F451B76F57D90BB6641DFFDE1A1821C4D783E4756F3CEE7F63B9BA284F8E114B0D9A086D83233BED4A8F5B60933DC16AF4DDE19C9FC59BCC1646343ECE7007B1C4DC65C4A939CDD47F6ED8855913183149BECE66D8FE7793AE607EB8E28513749B9548252764110D3B58D1D8B348DB18F7F24F8CA0C7D9CB515D90F7F1848FF58472B2EF52EBAB123AFC7F87890CE9FC55B31160014294A9B7F81638A27335E29E15A10B1068D5E049B1C239814DBBCC1BB30E11EEBAD5ACF8FB1B986C4F48D73FEA6129D9708A0B5AC435402BEC8C79C71DB94394811B9A604141A125A4669F9A139A0264E93E822117BE8E0D93A1487C51214E9FBF5763A3FBE9DA700B9C9B435472AF9F0B4446B000000003239307DD8B645100001D60B90300000CA1EC9E9B1C467FB020000000004595A
+...

lldb/lit/Modules/ELF/minidebuginfo-set-and-hit-breakpoint.test

@@ -0,0 +1,86 @@
+# REQUIRES: system-linux, lzma, xz
+
+# We want to keep the symbol "multiplyByThree" in the .dynamic section and not
+# have it put the default .symtab section.
+# RUN: echo "{multiplyByThree;};" > %T/dynmic-symbols.txt
+# RUN: %clang -Wl,--dynamic-list=%T/dynmic-symbols.txt -g -o %t.binary %p/Inputs/minidebuginfo-main.c
+
+# The following section is adapted from GDB's official documentation:
+# http://sourceware.org/gdb/current/onlinedocs/gdb/MiniDebugInfo.html#MiniDebugInfo
+
+# Extract the dynamic symbols from the main binary, there is no need
+# to also have these in the normal symbol table.
+
+# IGNORE: llvm-nm -D %t.binary --format=posix --defined-only | awk '{ print $1 }' | sort > %t.dynsyms
+
+# Extract all the text (i.e. function) symbols from the debuginfo.
+# (Note that we actually also accept "D" symbols, for the benefit
+# of platforms like PowerPC64 that use function descriptors.)
+
+# IGNORE: llvm-nm %t.binary --format=posix --defined-only | awk '{ if ($2 == "T" || $2 == "t" || $2 == "D") print $1 }' | sort > %t.funcsyms
+
+# Keep all the function symbols not already in the dynamic symbol
+# table.
+
+# IGNORE: comm -13 %t.dynsyms %t.funcsyms > %t.keep_symbols
+# The result of the preceeding command can be preprocessed in %p/Inputs/minidebuginfo.keep_symbols
+# because we know what symbol to keep.
+# RUN: echo "multiplyByFour" > %p/Inputs/minidebuginfo.keep_symbols
+
+# Separate full debug info into debug binary.
+
+# RUN: llvm-objcopy --only-keep-debug %t.binary %t.debug
+
+# Copy the full debuginfo, keeping only a minimal set of symbols and
+# removing some unnecessary sections.
+
+# RUN: llvm-objcopy -S --remove-section .gdb_index --remove-section .comment --keep-symbols=%p/Inputs/minidebuginfo.keep_symbols %t.debug %t.mini_debuginfo
+
+# This command is not from the GDB manual but it slims down embedded minidebug
+# info. On top if that, it ensures that we only have the multiplyByThree symbol
+# in the .dynsym section of the main binary.
+# RUN: llvm-objcopy --remove-section=.rela.dyn --remove-section=.gnu.version --remove-section=.gnu.hash --remove-section=.dynsym %t.mini_debuginfo
+
+# Drop the full debug info from the original binary.
+
+# RUN: llvm-strip --strip-all -R .comment %t.binary
+
+# Inject the compressed data into the .gnu_debugdata section of the
+# original binary.
+
+# RUN: xz --force --keep %t.mini_debuginfo
+
+# RUN: llvm-objcopy --add-section .gnu_debugdata=%t.mini_debuginfo.xz %t.binary
+
+# Now run the binary and see that we can set and hit a breakpoint
+# from within the .dynsym section (multiplyByThree) and one from
+# the .symtab section embedded in the .gnu_debugdata section (multiplyByFour).
+
+# RUN: %lldb -b -o 'b multiplyByThree' -o 'b multiplyByFour' -o 'run' -o 'continue' -o 'breakpoint list -v' %t.binary | FileCheck %s
+
+# CHECK: (lldb) b multiplyByThree
+# CHECK-NEXT: Breakpoint 1: where = minidebuginfo-set-and-hit-breakpoint.test.tmp.binary`multiplyByThree, address = 0x{{.*}}
+
+# CHECK: (lldb) b multiplyByFour
+# CHECK-NEXT: Breakpoint 2: where = minidebuginfo-set-and-hit-breakpoint.test.tmp.binary`multiplyByFour, address = 0x{{.*}}
+
+# CHECK: * thread #1, name = 'minidebuginfo-s', stop reason = breakpoint 1.1
+# CHECK: * thread #1, name = 'minidebuginfo-s', stop reason = breakpoint 2.1
+
+# CHECK: (lldb) breakpoint list -v
+# CHECK-NEXT: Current breakpoints:
+# CHECK-NEXT: 1: name = 'multiplyByThree'
+# CHECK-NEXT:  1.1: 
+# CHECK-NEXT:  module = {{.*}}/minidebuginfo-set-and-hit-breakpoint.test.tmp.binary
+# CHECK-NEXT:  symbol = multiplyByThree
+# CHECK-NEXT:  address = 0x{{.*}}
+# CHECK-NEXT:  resolved = true
+# CHECK-NEXT:  hit count = 1 
+
+# CHECK: 2: name = 'multiplyByFour'
+# CHECK-NEXT:  2.1: 
+# CHECK-NEXT:  module = {{.*}}/minidebuginfo-set-and-hit-breakpoint.test.tmp.binary
+# CHECK-NEXT:  symbol = multiplyByFour
+# CHECK-NEXT:  address = 0x{{.*}}
+# CHECK-NEXT:  resolved = true
+# CHECK-NEXT:  hit count = 1 

lldb/lit/lit.cfg.py

@@ -11,6 +11,7 @@
 from lit.llvm import llvm_config
 from lit.llvm.subst import FindTool
 from lit.llvm.subst import ToolSubst
+from distutils.spawn import find_executable
 
 site.addsitedir(os.path.dirname(__file__))
 from helper import toolchain
@@ -98,3 +99,9 @@ def calculate_arch_features(arch_string):
 
 if not config.lldb_disable_python:
     config.available_features.add('python')
+
+if config.lldb_enable_lzma:
+    config.available_features.add('lzma')
+
+if find_executable('xz') != None:
+    config.available_features.add('xz')

lldb/lit/lit.site.cfg.py.in

@@ -15,6 +15,7 @@ config.lldb_lit_tools_dir = r"@LLDB_LIT_TOOLS_DIR@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.python_executable = "@PYTHON_EXECUTABLE@"
 config.have_zlib = @LLVM_ENABLE_ZLIB@
+config.lldb_enable_lzma = @LLDB_ENABLE_LZMA@
 config.host_triple = "@LLVM_HOST_TRIPLE@"
 config.lldb_bitness = 64 if @LLDB_IS_64_BITS@ else 32
 config.lldb_disable_python = @LLDB_DISABLE_PYTHON@

lldb/source/Host/CMakeLists.txt

@@ -29,6 +29,7 @@ add_host_subdirectory(common
   common/HostProcess.cpp
   common/HostThread.cpp
   common/LockFileBase.cpp
+  common/LZMA.cpp
   common/MainLoop.cpp
   common/MonitoringProcessLauncher.cpp
   common/NativeProcessProtocol.cpp
@@ -157,6 +158,9 @@ endif()
 if (NOT LLDB_DISABLE_LIBEDIT)
   list(APPEND EXTRA_LIBS ${libedit_LIBRARIES})
 endif()
+if (LLDB_ENABLE_LZMA)
+  list(APPEND EXTRA_LIBS ${LIBLZMA_LIBRARIES})
+endif()
 
 if (NOT LLDB_DISABLE_LIBEDIT)
   list(APPEND LLDB_LIBEDIT_LIBS ${libedit_LIBRARIES})