When we're compiling with -pg make sure to link with gcrt1.o on linux. Be

sure to do this always, this matches the behavior for the gcc driver.

Fixes PR16251.

Based on a patch by Qiao Yang.

llvm-svn: 183591

clang/lib/Driver/Tools.cpp

@@ -6076,7 +6076,9 @@ void gnutools::Link::ConstructJob(Compilation &C, const JobAction &JA,
     if (!isAndroid) {
       const char *crt1 = NULL;
       if (!Args.hasArg(options::OPT_shared)){
-        if (IsPIE)
+        if (Args.hasArg(options::OPT_pg))
+          crt1 = "gcrt1.o";
+        else if (IsPIE)
           crt1 = "Scrt1.o";
         else
           crt1 = "crt1.o";

clang/test/Driver/linux-ld.c

@@ -667,3 +667,9 @@
 // RUN:   | FileCheck --check-prefix=CHECK-NOCRTFASTMATH %s
 // CHECK-CRTFASTMATH: usr/lib/gcc/x86_64-unknown-linux/4.6.0/crtfastmath.o
 // CHECK-NOCRTFASTMATH-NOT: crtfastmath.o
+
+// Check that we link in gcrt1.o when compiling with -pg
+// RUN: %clang -pg -target x86_64-unknown-linux -### %s \
+// RUN:        --sysroot=%S/Inputs/basic_linux_tree 2>& 1 \
+// RUN:   | FileCheck --check-prefix=CHECK-PG %s
+// CHECK-PG: gcrt1.o