[Profile] Enable profile merging with -fprofile-generat[=<dir>]

This patch enables raw profile merging for this option which is the
new intended behavior.

llvm-svn: 276484

clang/docs/UsersManual.rst

@@ -1546,27 +1546,31 @@ profile creation and use.
   The ``-fprofile-generate`` and ``-fprofile-generate=`` flags will use
   an alterantive instrumentation method for profile generation. When
   given a directory name, it generates the profile file
-  ``default.profraw`` in the directory named ``dirname``. If ``dirname``
-  does not exist, it will be created at runtime. The environment variable
-  ``LLVM_PROFILE_FILE`` can be used to override the directory and
-  filename for the profile file at runtime. For example,
+  ``default_%m.profraw`` in the directory named ``dirname`` if specified.
+  If ``dirname`` does not exist, it will be created at runtime. ``%m`` specifier
+  will be substibuted with a unique id documented in step 2 above. In other words,
+  with ``-fprofile-generate[=<dirname>]`` option, the "raw" profile data automatic
+  merging is turned on by default, so there will no longer any risk of profile
+  clobbering from different running processes.  For example,
 
   .. code-block:: console
 
     $ clang++ -O2 -fprofile-generate=yyy/zzz code.cc -o code
 
   When ``code`` is executed, the profile will be written to the file
-  ``yyy/zzz/default.profraw``. This can be altered at runtime via the
-  ``LLVM_PROFILE_FILE`` environment variable:
+  ``yyy/zzz/default_xxxx.profraw``.
 
-  .. code-block:: console
+  To generate the profile data file with the compiler readable format, the 
+  ``llvm-profdata`` tool can be used with the profile directory as the input:
 
-    $ LLVM_PROFILE_FILE=/tmp/myprofile/code.profraw ./code
+   .. code-block:: console
 
-  The above invocation will produce the profile file
-  ``/tmp/myprofile/code.profraw`` instead of ``yyy/zzz/default.profraw``.
-  Notice that ``LLVM_PROFILE_FILE`` overrides the directory *and* the file
-  name for the profile file.
+     $ llvm-profdata merge -output=code.profdata yyy/zzz/
+
+ If the user wants to turn off the auto-merging feature, or simply override the
+ the profile dumping path specified at command line, the environment variable
+ ``LLVM_PROFILE_FILE`` can still be used to override
+ the directory and filename for the profile file at runtime.
 
 .. option:: -fprofile-use[=<pathname>]
 

clang/lib/CodeGen/BackendUtil.cpp

@@ -456,7 +456,7 @@ void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
     if (!CodeGenOpts.InstrProfileOutput.empty())
       PMBuilder.PGOInstrGen = CodeGenOpts.InstrProfileOutput;
     else
-      PMBuilder.PGOInstrGen = "default.profraw";
+      PMBuilder.PGOInstrGen = "default_%m.profraw";
   }
   if (CodeGenOpts.hasProfileIRUse())
     PMBuilder.PGOInstrUse = CodeGenOpts.ProfileInstrumentUsePath;

clang/lib/Driver/Tools.cpp

@@ -3609,7 +3609,7 @@ static void addPGOAndCoverageFlags(Compilation &C, const Driver &D,
     if (PGOGenerateArg->getOption().matches(
             options::OPT_fprofile_generate_EQ)) {
       SmallString<128> Path(PGOGenerateArg->getValue());
-      llvm::sys::path::append(Path, "default.profraw");
+      llvm::sys::path::append(Path, "default_%m.profraw");
       CmdArgs.push_back(
           Args.MakeArgString(Twine("-fprofile-instrument-path=") + Path));
     }

clang/test/Driver/clang_f_opts.c

@@ -99,7 +99,7 @@
 // RUN: %clang -### -S -fprofile-instr-generate -fcoverage-mapping -fno-coverage-mapping %s 2>&1 | FileCheck -check-prefix=CHECK-DISABLE-COVERAGE %s
 // CHECK-PROFILE-GENERATE: "-fprofile-instrument=clang"
 // CHECK-PROFILE-GENERATE-LLVM: "-fprofile-instrument=llvm"
-// CHECK-PROFILE-GENERATE-DIR: "-fprofile-instrument-path=/some/dir{{/|\\\\}}default.profraw"
+// CHECK-PROFILE-GENERATE-DIR: "-fprofile-instrument-path=/some/dir{{/|\\\\}}{{.*}}"
 // CHECK-PROFILE-GENERATE-FILE: "-fprofile-instrument-path=/tmp/somefile.profraw"
 // CHECK-NO-MIX-GEN-USE: '{{[a-z=-]*}}' not allowed with '{{[a-z=-]*}}'
 // CHECK-NO-MIX-GENERATE: '{{[a-z=-]*}}' not allowed with '{{[a-z=-]*}}'

clang/test/Profile/gcc-flag-compatibility.c

@@ -12,7 +12,7 @@
 
 // Check that -fprofile-generate=/path/to generates /path/to/default.profraw
 // RUN: %clang %s -c -S -o - -emit-llvm -fprofile-generate=/path/to | FileCheck -check-prefix=PROFILE-GEN-EQ %s
-// PROFILE-GEN-EQ: constant [25 x i8] c"/path/to{{/|\\5C}}default.profraw\00"
+// PROFILE-GEN-EQ: constant [{{.*}} x i8] c"/path/to{{/|\\5C}}{{.*}}\00"
 
 // Check that -fprofile-use=some/path reads some/path/default.profdata
 // RUN: rm -rf %t.dir