[llvm-symbolizer] Support reading options from environment

llvm-symbolizer is used by sanitizers to symbolize errors discovered by
sanitizer, but there's no way to pass options to llvm-symbolizer since
the tool is invoked directly by the sanitizer runtime. Therefore, we
don't have a way to pass options needed to find debug symbols such as
-dsym-hint or -debug-file-directory. This change enables reading options
from the LLVM_SYMBOLIZER_OPTS in addition to command line which can be
used to pass those additional options to llvm-symbolizer invocations
made by sanitizer runtime.

Differential Revision: https://reviews.llvm.org/D71668

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/docs/CommandGuide/llvm-symbolizer.rst b/llvm/docs/CommandGuide/llvm-symbolizer.rst
index b157f94ef22..bb60246c835 100644
--- a/llvm/docs/CommandGuide/llvm-symbolizer.rst
+++ b/llvm/docs/CommandGuide/llvm-symbolizer.rst
@@ -28,6 +28,12 @@ Object files can be specified together with the addresses either on standard
 input or as positional arguments on the command-line, following any "DATA" or
 "CODE" prefix.
 
+:program:`llvm-symbolizer` parses options from the environment variable
+``LLVM_SYMBOLIZER_OPTS`` after parsing options from the command line.
+``LLVM_SYMBOLIZER_OPTS`` is primarily useful for supplementing the command-line
+options when :program:`llvm-symbolizer` is invoked by another program or
+runtime.
+
 EXAMPLES
 --------