[MinGW] Add the profiling library when necessary

[mstorsjo]

Summary

Profiling still doesn't seem to work properly, but this at least hooks up the library and eases completing whatever is missing.

[rnk]

lgtm

[davezarzycki]

This change breaks building/testing the compiler with CLANG_DEFAULT_LINKER set to lld. Was this intentional? What should people do if they want to use CLANG_DEFAULT_LINKER and run the test suite?

[mstorsjo]

In D58107#1396063, @davezarzycki wrote:

This change breaks building/testing the compiler with CLANG_DEFAULT_LINKER set to lld. Was this intentional? What should people do if they want to use CLANG_DEFAULT_LINKER and run the test suite?

It wasn't intentional. Originally I added -fuse-ld=lld to the test, but this broke buildbots that didn't have lld available. My fixup in rC353922 avoided this by removing the -fuse-ld=lld (where I noted in the commit message that I guess that it would break such configurations). At that point I thought the other tests in this same file also would be equally broken in such a setup then. But I see that most other tests use -fuse-ld=ld, to work around this. (This option doesn't check if the named tool exists, contrary to -fuse-ld=<any-other-string>.)

But if a linker named <triplet>-ld exists, that will be used instead, so I'll need to make the regex a bit looser as well. I'll commit a fix for this soon.

lib/Driver/ToolChains/MinGW.cpp

if (!Args.hasArg(options::OPT_nodefaultlibs)) {
         // Make sure the linker consider all object files from the dynamic
         // runtime thunk.
         CmdArgs.push_back("--whole-archive");
         CmdArgs.push_back(
             TC.getCompilerRTArgString(Args, "asan_dynamic_runtime_thunk"));
         CmdArgs.push_back("--no-whole-archive");
       }
 
+      TC.addProfileRTLibs(Args, CmdArgs);
+
       if (!HasWindowsApp) {
         // Add system libraries. If linking to libwindowsapp.a, that import
         // library replaces all these and we shouldn't accidentally try to
         // link to the normal desktop mode dlls.
         if (Args.hasArg(options::OPT_mwindows)) {
           CmdArgs.push_back("-lgdi32");
           CmdArgs.push_back("-lcomdlg32");
         }

test/Driver/instrprof-ld.c

 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target x86_64-pc-win32 -fprofile-instr-generate \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:   | FileCheck --check-prefix=CHECK-WINDOWS-X86-64 %s
 //
 // CHECK-WINDOWS-X86-64: "{{.*}}link{{(.exe)?}}"
 // CHECK-WINDOWS-X86-64: "{{.*}}clang_rt.profile-x86_64.lib"
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 -fuse-ld=lld \
+// RUN:     -target x86_64-mingw32 -fprofile-instr-generate \
+// RUN:     -resource-dir=%S/Inputs/resource_dir \
+// RUN:   | FileCheck --check-prefix=CHECK-MINGW-X86-64 %s
+//
+// CHECK-MINGW-X86-64: "{{(.*[^-.0-9A-Z_a-z])?}}ld.lld{{(.exe)?}}"
+// CHECK-MINGW-X86-64: "{{.*}}/Inputs/resource_dir{{/|\\\\}}lib{{/|\\\\}}windows{{/|\\\\}}libclang_rt.profile-x86_64.a"