[MachineOutliner] Never add the outliner in -O0

This is a recommit of r335879.

We shouldn't add the outliner when compiling at -O0 even if
-enable-machine-outliner is passed in. This makes sure that we
don't add it in this case.

This also removes -O0 from the outliner DWARF test.

llvm-svn: 335930

llvm/lib/CodeGen/TargetPassConfig.cpp

@@ -906,7 +906,7 @@ void TargetPassConfig::addMachinePasses() {
   addPass(&XRayInstrumentationID, false);
   addPass(&PatchableFunctionID, false);
 
-  if (TM->Options.EnableMachineOutliner &&
+  if (TM->Options.EnableMachineOutliner && getOptLevel() != CodeGenOpt::None &&
       EnableMachineOutliner)
     addPass(createMachineOutlinerPass());
 

llvm/test/CodeGen/AArch64/machine-outliner-flags.ll

@@ -0,0 +1,30 @@
+; RUN: llc %s -debug-pass=Structure -verify-machineinstrs \
+; RUN: -enable-machine-outliner -mtriple arm64---- -o /dev/null 2>&1 \
+; RUN: | FileCheck %s -check-prefix=ENABLE
+
+; RUN: llc %s -debug-pass=Structure -verify-machineinstrs \
+; RUN: -mtriple arm64---- -o /dev/null 2>&1 \
+; RUN: | FileCheck %s -check-prefix=NOT-ADDED
+
+; RUN: llc %s -O=0 -debug-pass=Structure -verify-machineinstrs \
+; RUN: -mtriple arm64---- -o /dev/null 2>&1 \
+; RUN: | FileCheck %s -check-prefix=OPTNONE
+
+; Make sure that the outliner is added to the pass pipeline only when the
+; appropriate flags/settings are set. Make sure it isn't added otherwise.
+;
+; Cases where it should be added:
+;  * -enable-machine-outliner
+;
+; Cases where it should not be added:
+;  * -O0 or equivalent
+;  * -enable-machine-outliner is not passed
+
+; ENABLE: Machine Outliner
+; NOT-ADDED-NOT: Machine Outliner
+; OPTNONE-NOT: Machine Outliner
+
+define void @foo() {
+  ret void;
+}
+

llvm/test/DebugInfo/AArch64/machine-outliner.ll

@@ -1,4 +1,4 @@
-; RUN: llc -O0 -verify-machineinstrs -filetype=obj -mtriple=aarch64-- \
+; RUN: llc -verify-machineinstrs -filetype=obj -mtriple=aarch64-- \
 ; RUN: -enable-machine-outliner < %s | llvm-dwarfdump - | FileCheck %s
 
 ; Ensure that the MachineOutliner produces valid DWARF when it creates outlined