[Clang][NewPM] Don't bail out if the target machine is empty

[phosek]

Summary

This matches the behavior of the old pass manager. There are some
targets that don't have target machine at all (e.g. le32, spir) which
whose tests would never run with new pass manager. Similarly, we would
need to disable tests for targets that are disabled.

[phosek]

Ping?

[chandlerc]

Maybe update at least some of the tests using these targets to additionally run with the new pass manager explicitly enabled via flag?

clang/lib/CodeGen/BackendUtil.cpp

958–963

I would say RequiresCodeGen instead of UsesCodeGen as we will still *use* the target manager even if it isn't required when emitting a .ll file.

[phosek]

In D58374#1411376, @chandlerc wrote:

Maybe update at least some of the tests using these targets to additionally run with the new pass manager explicitly enabled via flag?

Done

[chandlerc]

LGTM!

clang/lib/CodeGen/BackendUtil.cpp

 ///
 /// This API is planned to have its functionality finished and then to replace
 /// `EmitAssembly` at some point in the future when the default switches.
 void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
     BackendAction Action, std::unique_ptr<raw_pwrite_stream> OS) {
   TimeRegion Region(FrontendTimesIsEnabled ? &CodeGenerationTime : nullptr);
   setCommandLineOpts(CodeGenOpts);
 
-  // The new pass manager always makes a target machine available to passes
-  // during construction.
-  CreateTargetMachine(/*MustCreateTM*/ true);
-  if (!TM)
-    // This will already be diagnosed, just bail.
+  bool RequiresCodeGen = (Action != Backend_EmitNothing &&
+                          Action != Backend_EmitBC &&
+                          Action != Backend_EmitLL);
+  CreateTargetMachine(RequiresCodeGen);
+
+  if (RequiresCodeGen && !TM)
     return;
+  if (TM)
     TheModule->setDataLayout(TM->createDataLayout());
 
   Optional<PGOOptions> PGOOpt;
 
   if (CodeGenOpts.hasProfileIRInstr())
     // -fprofile-generate.
     PGOOpt = PGOOptions(CodeGenOpts.InstrProfileOutput.empty()
                             ? DefaultProfileGenName
                             : CodeGenOpts.InstrProfileOutput,

clang/test/CodeGen/spir-half-type.cpp

 // RUN: %clang_cc1 -O0 -triple spir -emit-llvm %s -o - | FileCheck %s
 // RUN: %clang_cc1 -O0 -triple spir64 -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -O0 -triple spir -fexperimental-new-pass-manager -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -O0 -triple spir64 -fexperimental-new-pass-manager -emit-llvm %s -o - | FileCheck %s
 
 // This file tests that using the _Float16 type with the spir target will not
 // use the llvm intrinsics but instead will use the half arithmetic
 // instructions directly.
 
 // Previously attempting to use a constant _Float16 with a comparison
 // instruction when the target is spir or spir64 lead to an assert being hit.
 bool fcmp_const() {

clang/test/Driver/le32-unknown-nacl.cpp

 // RUN: %clang -target le32-unknown-nacl -### %s -emit-llvm-only -c 2>&1 | FileCheck %s -check-prefix=ECHO
 // RUN: %clang -target le32-unknown-nacl %s -emit-llvm -S -c -o - | FileCheck %s
+// RUN: %clang -target le32-unknown-nacl -fexperimental-new-pass-manager %s -emit-llvm -S -c -o - | FileCheck %s
 // RUN: %clang -target le32-unknown-nacl %s -emit-llvm -S -c -pthread -o - | FileCheck %s -check-prefix=THREADS
 
 // ECHO: {{.*}} "-cc1" {{.*}}le32-unknown-nacl.c
 
 typedef __builtin_va_list va_list;
 typedef __SIZE_TYPE__ size_t;
 typedef __PTRDIFF_TYPE__ ptrdiff_t;