[msan] Change track-origins default mode from 1 to 2.

Change -fsanitize-memory-track-origins to be equivalent to
-fsanitize-memory-track-origins=2.

Track-origins=2 provides a lot more detailed reports at the cost of
some additional slowdown (ranging from none to, sometimes, 3x; ~3% average on
SPEC2006).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@230644 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/MemorySanitizer.rst b/docs/MemorySanitizer.rst
index 8841fc3501dac78e021327033289b057f0e47547..007e0866dec6ff404ff81e4c9362e408e56d1132 100644 (file)
--- a/docs/MemorySanitizer.rst
+++ b/docs/MemorySanitizer.rst
@@ -110,30 +110,10 @@ Origin Tracking
 
 MemorySanitizer can track origins of unitialized values, similar to
 Valgrind's --track-origins option. This feature is enabled by
-``-fsanitize-memory-track-origins`` Clang option. With the code from
+``-fsanitize-memory-track-origins=2`` (or simply
+``-fsanitize-memory-track-origins``) Clang option. With the code from
 the example above,
 
-.. code-block:: console
-
-    % clang -fsanitize=memory -fsanitize-memory-track-origins -fno-omit-frame-pointer -g -O2 umr.cc
-    % ./a.out
-    WARNING: MemorySanitizer: use-of-uninitialized-value
-        #0 0x7f7893912f0b in main umr2.cc:6
-        #1 0x7f789249b76c in __libc_start_main libc-start.c:226
-
-      Uninitialized value was created by a heap allocation
-        #0 0x7f7893901cbd in operator new[](unsigned long) msan_new_delete.cc:44
-        #1 0x7f7893912e06 in main umr2.cc:4
-
-Origin tracking has proved to be very useful for debugging MemorySanitizer
-reports. It slows down program execution by a factor of 1.5x-2x on top
-of the usual MemorySanitizer slowdown.
-
-MemorySanitizer can provide even more information with
-``-fsanitize-memory-track-origins=2`` flag. In this mode reports
-include information about intermediate stores the uninitialized value went
-through.
-
 .. code-block:: console
 
     % cat umr2.cc
@@ -162,6 +142,15 @@ through.
         #0 0x7f7893901cbd in operator new[](unsigned long) msan_new_delete.cc:44
         #1 0x7f7893912e06 in main umr2.cc:4
 
+By default, MemorySanitizer collects both allocation points and all
+intermediate stores the uninitialized value went through.  Origin
+tracking has proved to be very useful for debugging MemorySanitizer
+reports. It slows down program execution by a factor of 1.5x-2x on top
+of the usual MemorySanitizer slowdown.
+
+Clang option ``-fsanitize-memory-track-origins=1`` enabled a slightly
+faster mode when MemorySanitizer collects only allocation points but
+not intermediate stores.
 
 Handling external code
 ============================

diff --git a/docs/UsersManual.rst b/docs/UsersManual.rst
index d4a7b3eed1fa06afaec37af0cf60bbc2e140271c..1685670d0a8e14231effcc884804b7a1afb821ac 100644 (file)
--- a/docs/UsersManual.rst
+++ b/docs/UsersManual.rst
@@ -1030,10 +1030,11 @@ are listed below.
       uninitialized bits came from. Slows down execution by additional
       1.5x-2x.
 
-      Possible values for level are 0 (off), 1 (default), 2. Level 2 adds more
-      sections to MemorySanitizer reports describing the order of memory stores
-      the uninitialized value went through. Beware, this mode may use a lot of
-      extra memory.
+      Possible values for level are 0 (off), 1, 2 (default). Level 2
+      adds more sections to MemorySanitizer reports describing the
+      order of memory stores the uninitialized value went
+      through. This mode may use extra memory in programs that copy
+      uninitialized memory a lot.
 
    Extra features of UndefinedBehaviorSanitizer:
 

diff --git a/lib/Driver/SanitizerArgs.cpp b/lib/Driver/SanitizerArgs.cpp
index 0488abceabcac68b0c66ab1df33e02db5e98a388..11b92881f3408dff7955b9ac1583d92e9520ea2f 100644 (file)
--- a/lib/Driver/SanitizerArgs.cpp
+++ b/lib/Driver/SanitizerArgs.cpp
@@ -360,7 +360,7 @@ SanitizerArgs::SanitizerArgs(const ToolChain &TC,
                             options::OPT_fsanitize_memory_track_origins,
                             options::OPT_fno_sanitize_memory_track_origins)) {
       if (A->getOption().matches(options::OPT_fsanitize_memory_track_origins)) {
-        MsanTrackOrigins = 1;
+        MsanTrackOrigins = 2;
       } else if (A->getOption().matches(
                      options::OPT_fno_sanitize_memory_track_origins)) {
         MsanTrackOrigins = 0;

diff --git a/test/Driver/fsanitize.c b/test/Driver/fsanitize.c
index 8f37b02580a13b0f06cd77a769b877571f4bfcb4..97232e30a9b9b7a146e4dd6d23267c58a227cbfb 100644 (file)
--- a/test/Driver/fsanitize.c
+++ b/test/Driver/fsanitize.c
@@ -66,11 +66,13 @@
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -pie %s -### 2>&1
 // OK
 
-// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-1
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-2
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins=1 -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-1
-// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins=2 -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-1
-// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fno-sanitize-memory-track-origins -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-1
-// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins=0 -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-1
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins=1 -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-2
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins=2 -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-2
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fno-sanitize-memory-track-origins -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-2
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins=0 -fsanitize-memory-track-origins=1 -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-1
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-track-origins=0 -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-TRACK-ORIGINS-2
 
 // CHECK-TRACK-ORIGINS-1: -fsanitize-memory-track-origins=1