[PGO] Change profile use cc1 option to handle IR level profiles

This patch changes cc1 option for PGO profile use from
-fprofile-instr-use=<path> to -fprofile-instrument-use-path=<path>.
-fprofile-instr-use=<path> is now a driver only option.

In addition to decouple the cc1 option from the driver level option, this patch
also enables IR level profile use. cc1 option handling now reads the profile
header and sets CodeGenOpt ProfileUse (valid values are {None, Clang, LLVM}
-- this is a common enum for -fprofile-instrument={}, for the profile
instrumentation), and invoke the pipeline to enable the respective PGO use pass.

Reviewers: silvas, davidxl

Differential Revision: http://reviews.llvm.org/D17737

llvm-svn: 262515
diff --git a/clang/test/CodeGen/pgo-instrumentation.c b/clang/test/CodeGen/pgo-instrumentation.c
index f78ab20..1dac36f 100644
--- a/clang/test/CodeGen/pgo-instrumentation.c
+++ b/clang/test/CodeGen/pgo-instrumentation.c
@@ -7,3 +7,14 @@
 // Ensure Pass PGOInstrumentationGenPass is not invoked.
 // RUN: %clang_cc1 -O2 -fprofile-instrument=clang %s -mllvm -debug-pass=Structure -emit-llvm -o - 2>&1 | FileCheck %s -check-prefix=CHECK-PGOGENPASS-INVOKED-INSTR-GEN-CLANG
 // CHECK-PGOGENPASS-INVOKED-INSTR-GEN-CLANG-NOT: PGOInstrumentationGenPass
+
+// Ensure Pass PGOInstrumentationUsePass is invoked.
+// RUN: llvm-profdata merge -o %t.profdata %S/Inputs/pgotestir.profraw
+// RUN: %clang_cc1 -O2 -fprofile-instrument-use-path=%t.profdata %s -mllvm -debug-pass=Structure -emit-llvm -o - 2>&1 | FileCheck %s -check-prefix=CHECK-PGOUSEPASS-INVOKED-INSTR-USE
+// CHECK-PGOUSEPASS-INVOKED-INSTR-USE: PGOInstrumentationUsePass
+//
+// Ensure Pass PGOInstrumentationUsePass is not invoked.
+// RUN: llvm-profdata merge -o %t.profdata %S/Inputs/pgotestclang.profraw
+// RUN: %clang_cc1 -O2 -fprofile-instrument-use-path=%t.profdata %s -mllvm -debug-pass=Structure -emit-llvm -o - 2>&1 | FileCheck %s -check-prefix=CHECK-PGOUSEPASS-INVOKED-USE-CLANG
+// CHECK-PGOUSEPASS-INVOKED-USE-CLANG-NOT: PGOInstrumentationUsePass
+