[sanitizer-coverage] emit __sanitizer_cov_trace_pc_guard w/o a preceding 'if' by default. Update the docs, also add deprecation notes around other parts of sanitizer coverage

llvm-svn: 292862

4 files changed, 16 insertions, 10 deletions

diff --git a/clang/docs/SanitizerCoverage.rst b/clang/docs/SanitizerCoverage.rst
index 3e8102a12f6..8ec6871d795 100644
--- a/clang/docs/SanitizerCoverage.rst
+++ b/clang/docs/SanitizerCoverage.rst
@@ -227,7 +227,8 @@ easily used for bitset-based corpus distillation.
 Caller-callee coverage
 ======================
 
-(Experimental!)
+**Deprecated, don't use**
+
 Every indirect function call is instrumented with a run-time function call that
 captures caller and callee.  At the shutdown time the process dumps a separate
 file called ``caller-callee.PID.sancov`` which contains caller/callee pairs as
@@ -253,6 +254,8 @@ Current limitations:
 Coverage counters
 =================
 
+**Deprecated, don't use**
+
 This experimental feature is inspired by
 `AFL <http://lcamtuf.coredump.cx/afl/technical_details.txt>`__'s coverage
 instrumentation. With additional compile-time and run-time flags you can get
@@ -296,6 +299,9 @@ These counters may also be used for in-process coverage-guided fuzzers. See
 
 Tracing basic blocks
 ====================
+
+**Deprecated, don't use**
+
 Experimental support for basic block (or edge) tracing.
 With ``-fsanitize-coverage=trace-bb`` the compiler will insert
 ``__sanitizer_cov_trace_basic_block(s32 *id)`` before every function, basic block, or edge
@@ -319,6 +325,9 @@ Basic block tracing is currently supported only for single-threaded applications
 
 Tracing PCs
 ===========
+
+**Deprecated, don't use**
+
 *Experimental* feature similar to tracing basic blocks, but with a different API.
 With ``-fsanitize-coverage=trace-pc`` the compiler will insert
 ``__sanitizer_cov_trace_pc()`` on every edge.
@@ -331,16 +340,13 @@ and can be used with `AFL <http://lcamtuf.coredump.cx/afl>`__.
 
 Tracing PCs with guards
 =======================
-Another *experimental* feature that tries to combine the functionality of `trace-pc`,
-`8bit-counters` and boolean coverage.
 
 With ``-fsanitize-coverage=trace-pc-guard`` the compiler will insert the following code
 on every edge:
 
 .. code-block:: none
 
-   if (guard_variable)
-     __sanitizer_cov_trace_pc_guard(&guard_variable)
+   __sanitizer_cov_trace_pc_guard(&guard_variable)
 
 Every edge will have its own `guard_variable` (uint32_t).
 
@@ -352,7 +358,7 @@ The compler will also insert a module constructor that will call
    // This function may be called multiple times with the same values of start/stop.
    __sanitizer_cov_trace_pc_guard_init(uint32_t *start, uint32_t *stop);
 
-Similarly to `trace-pc,indirect-calls`, with `trace-pc-guards,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_*` should be defined by the user.
diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
index 5b4b1fb7713..e34dd611b25 100644
--- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -95,7 +95,7 @@ static cl::opt<unsigned> ClCoverageBlockThreshold(
     "sanitizer-coverage-block-threshold",
     cl::desc("Use a callback with a guard check inside it if there are"
              " more than this number of blocks."),
-    cl::Hidden, cl::init(500));
+    cl::Hidden, cl::init(0));
 
 static cl::opt<bool>
     ClExperimentalTracing("sanitizer-coverage-experimental-tracing",
diff --git a/llvm/test/Instrumentation/SanitizerCoverage/coverage.ll b/llvm/test/Instrumentation/SanitizerCoverage/coverage.ll
index a2a92a02c71..9dceceb2eef 100644
--- a/llvm/test/Instrumentation/SanitizerCoverage/coverage.ll
+++ b/llvm/test/Instrumentation/SanitizerCoverage/coverage.ll
@@ -1,6 +1,6 @@
 ; RUN: opt < %s -sancov -sanitizer-coverage-level=0 -S | FileCheck %s --check-prefix=CHECK0
 ; RUN: opt < %s -sancov -sanitizer-coverage-level=1 -S | FileCheck %s --check-prefix=CHECK1
-; RUN: opt < %s -sancov -sanitizer-coverage-level=2 -S | FileCheck %s --check-prefix=CHECK2
+; RUN: opt < %s -sancov -sanitizer-coverage-level=2 -S | FileCheck %s --check-prefix=CHECK_WITH_CHECK
 ; RUN: opt < %s -sancov -sanitizer-coverage-level=2 -sanitizer-coverage-block-threshold=10 -S | FileCheck %s --check-prefix=CHECK2
 ; RUN: opt < %s -sancov -sanitizer-coverage-level=2 -sanitizer-coverage-block-threshold=0  -S | FileCheck %s --check-prefix=CHECK_WITH_CHECK
 ; RUN: opt < %s -sancov -sanitizer-coverage-level=2 -sanitizer-coverage-block-threshold=1  -S | FileCheck %s --check-prefix=CHECK_WITH_CHECK
diff --git a/llvm/test/Instrumentation/SanitizerCoverage/coverage2-dbg.ll b/llvm/test/Instrumentation/SanitizerCoverage/coverage2-dbg.ll
index 37eca1065fd..fde1904259d 100644
--- a/llvm/test/Instrumentation/SanitizerCoverage/coverage2-dbg.ll
+++ b/llvm/test/Instrumentation/SanitizerCoverage/coverage2-dbg.ll
@@ -17,8 +17,8 @@ target triple = "x86_64-unknown-linux-gnu"
 ; Check that __sanitizer_cov call has !dgb pointing to the beginning
 ; of appropriate basic blocks.
 ; CHECK-LABEL:_Z3fooPi
-; CHECK: call void @__sanitizer_cov(i32*{{.*}}), !dbg [[A:!.*]]
-; CHECK: call void @__sanitizer_cov(i32*{{.*}}), !dbg [[B:!.*]]
+; CHECK: call void @__sanitizer_cov{{.*}}(i32*{{.*}}), !dbg [[A:!.*]]
+; CHECK: call void @__sanitizer_cov{{.*}}(i32*{{.*}}), !dbg [[B:!.*]]
 ; CHECK: ret void
 ; CHECK: [[A]] = !DILocation(line: 1, scope: !{{.*}})
 ; CHECK: [[B]] = !DILocation(line: 3, column: 5, scope: !{{.*}})