r281809 - [sanitizer-coverage] change trace-pc to use 8-byte guards

[Kostya Serebryany via cfe-commits]

Author: kcc
Date: Sat Sep 17 00:03:05 2016
New Revision: 281809

URL: http://llvm.org/viewvc/llvm-project?rev=281809&view=rev
Log:
[sanitizer-coverage] change trace-pc to use 8-byte guards

Modified:
    cfe/trunk/docs/SanitizerCoverage.rst

Modified: cfe/trunk/docs/SanitizerCoverage.rst
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/SanitizerCoverage.rst?rev=281809&r1=281808&r2=281809&view=diff
==============================================================================
--- cfe/trunk/docs/SanitizerCoverage.rst (original)
+++ cfe/trunk/docs/SanitizerCoverage.rst Sat Sep 17 00:03:05 2016
@@ -331,24 +331,23 @@ on every edge:
 
 .. code-block:: none
 
-   if (guard_variable != 0xff)
+   if (guard_variable >= 0)
      __sanitizer_cov_trace_pc_guard(&guard_variable)
 
-Every edge will have its own 1-byte `guard_variable`.
-All such guard variables will reside in a dedicated section
-(i.e. they essentially form an array).
-
-Similarly to `trace-pc,indirect-calls`, with `trace-pc-guards,indirect-calls`
-``__sanitizer_cov_trace_pc_indirect(void *callee)`` will be inserted on every indirect call.
+Every edge will have its own 8-byte `guard_variable`.
 
 The compler will also insert a module constructor that will call
 
 .. code-block:: c++
 
-   // The guard section is the address range [start, stop).
-   __sanitizer_cov_trace_pc_guard_init(void *start, void *stop);
+   // The guards are [start, stop).
+   // This function may be called multiple times with the same values of start/stop.
+   __sanitizer_cov_trace_pc_guard_init(uint64_t *start, uint64_t *stop);
+
+Similarly to `trace-pc,indirect-calls`, with `trace-pc-guards,indirect-calls`
+``__sanitizer_cov_trace_pc_indirect(void *callee)`` will be inserted on every indirect call.
 
-The functions `__sanitizer_cov_trace_pc_guard[_init]` should be defined by the user.
+The functions `__sanitizer_cov_trace_pc_*` should be defined by the user.
 
 Tracing data flow
 =================