r272214 - [docs] Coverage: Flesh out instructions for avoiding static initializeres

[Vedant Kumar via cfe-commits]

Author: vedantk
Date: Wed Jun  8 17:24:52 2016
New Revision: 272214

URL: http://llvm.org/viewvc/llvm-project?rev=272214&view=rev
Log:
[docs] Coverage: Flesh out instructions for avoiding static initializeres

Modified:
    cfe/trunk/docs/SourceBasedCodeCoverage.rst

Modified: cfe/trunk/docs/SourceBasedCodeCoverage.rst
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/SourceBasedCodeCoverage.rst?rev=272214&r1=272213&r2=272214&view=diff
==============================================================================
--- cfe/trunk/docs/SourceBasedCodeCoverage.rst (original)
+++ cfe/trunk/docs/SourceBasedCodeCoverage.rst Wed Jun  8 17:24:52 2016
@@ -192,14 +192,22 @@ By default the compiler runtime uses a s
 profile output path and to register a writer function. To collect profiles
 without using static initializers, do this manually:
 
-* Export a ``int __llvm_profile_runtime`` symbol. The linker won't pull in the
-  object file containing the profiling runtime's static initializer if this
-  symbol is defined.
+* Export a ``int __llvm_profile_runtime`` symbol from each instrumented shared
+  library and executable. When the linker finds a definition of this symbol, it
+  knows to skip loading the object which contains the profiling runtime's
+  static initializer.
 
-* Call ``__llvm_profile_initialize_file`` once. This parses
-  ``LLVM_PROFILE_FILE`` and sets the output path.
+* Forward-declare ``void __llvm_profile_initialize_file(void)`` and call it
+  once from each instrumented executable. This function parses
+  ``LLVM_PROFILE_FILE``, sets the output path, and truncates any existing files
+  at that path. To get the same behavior without truncating existing files,
+  pass a filename pattern string to ``void __llvm_profile_set_filename(char
+  *)``.  These calls can be placed anywhere so long as they precede all calls
+  to ``__llvm_profile_write_file``.
 
-* Call ``__llvm_profile_write_file`` to write out a profile.
+* Forward-declare ``int __llvm_profile_write_file(void)`` and call it to write
+  out a profile. Calling this function multiple times appends profile data to
+  an existing on-disk raw profile.
 
 Drawbacks and limitations
 =========================