[clang] 7dbfc4f - [clang] Document -femit-compact-unwind option in the User’s Manual

[Jez Ng via cfe-commits]

Author: Jez Ng
Date: 2022-07-14T16:50:36-04:00
New Revision: 7dbfc4fc065d7f1bd85988351399c7fd2db1ec53

URL: https://github.com/llvm/llvm-project/commit/7dbfc4fc065d7f1bd85988351399c7fd2db1ec53
DIFF: https://github.com/llvm/llvm-project/commit/7dbfc4fc065d7f1bd85988351399c7fd2db1ec53.diff

LOG: [clang] Document -femit-compact-unwind option in the User’s Manual

Reviewed By: #lld-macho, thakis

Differential Revision: https://reviews.llvm.org/D129772

Added: 
    

Modified: 
    clang/docs/UsersManual.rst

Removed: 
    


################################################################################
diff  --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index c2767d65adbf..1d11b00a1a78 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -843,6 +843,23 @@ a special character, which is the convention used by GNU Make. The -MV
 option tells Clang to put double-quotes around the entire filename, which
 is the convention used by NMake and Jom.
 
+.. option:: -femit-dwarf-unwind=<value>
+
+  When to emit DWARF unwind (EH frame) info. This is a Mach-O-specific option.
+
+  Valid values are:
+
+  * ``no-compact-unwind`` - Only emit DWARF unwind when compact unwind encodings
+    aren't available. This is the default for arm64.
+  * ``always`` - Always emit DWARF unwind regardless.
+  * ``default`` - Use the platform-specific default (``always`` for all
+    non-arm64-platforms).
+
+``no-compact-unwind`` is a performance optimization -- Clang will emit smaller
+object files that are more quickly processed by the linker. This may cause
+binary compatibility issues on older x86_64 targets, however, so use it with
+caution.
+
 .. _configuration-files:
 
 Configuration files