Reject global ISel path for NPM

Author: vikramRH

llvm/include/llvm/CodeGen/TargetPassConfig.h

@@ -20,6 +20,7 @@
 #include <cassert>
 #include <string>
 
+
 namespace llvm {
 
 class TargetMachine;
@@ -478,6 +479,9 @@ class LLVM_ABI TargetPassConfig : public ImmutablePass {
 LLVM_ABI void registerCodeGenCallback(PassInstrumentationCallbacks &PIC,
                                       TargetMachine &);
 
+enum class SelectorType { SelectionDAG, FastISel, GlobalISel };
+SelectorType getSelectorType(TargetMachine& TM);
+
 } // end namespace llvm
 
 #endif // LLVM_CODEGEN_TARGETPASSCONFIG_H

llvm/include/llvm/Passes/CodeGenPassBuilder.h

@@ -937,21 +937,7 @@ Error CodeGenPassBuilder<Derived, TargetMachineT>::addCoreISelPasses(
   TM.setO0WantsFastISel(Opt.EnableFastISelOption.value_or(true));
 
   // Determine an instruction selector.
-  enum class SelectorType { SelectionDAG, FastISel, GlobalISel };
-  SelectorType Selector;
-
-  if (Opt.EnableFastISelOption && *Opt.EnableFastISelOption == true)
-    Selector = SelectorType::FastISel;
-  else if ((Opt.EnableGlobalISelOption &&
-            *Opt.EnableGlobalISelOption == true) ||
-           (TM.Options.EnableGlobalISel &&
-            (!Opt.EnableGlobalISelOption ||
-             *Opt.EnableGlobalISelOption == false)))
-    Selector = SelectorType::GlobalISel;
-  else if (TM.getOptLevel() == CodeGenOptLevel::None && TM.getO0WantsFastISel())
-    Selector = SelectorType::FastISel;
-  else
-    Selector = SelectorType::SelectionDAG;
+  SelectorType Selector = getSelectorType(TM);
 
   // Set consistently TM.Options.EnableFastISel and EnableGlobalISel.
   if (Selector == SelectorType::FastISel) {

llvm/lib/CodeGen/TargetPassConfig.cpp

@@ -550,6 +550,23 @@ void llvm::registerCodeGenCallback(PassInstrumentationCallbacks &PIC,
   });
 }
 
+SelectorType llvm::getSelectorType(TargetMachine& TM) {
+  SelectorType Selector;
+  if (EnableFastISelOption == cl::BOU_TRUE)
+    Selector = SelectorType::FastISel;
+  else if (EnableGlobalISelOption == cl::BOU_TRUE ||
+           (TM.Options.EnableGlobalISel &&
+            EnableGlobalISelOption != cl::BOU_FALSE))
+    Selector = SelectorType::GlobalISel;
+  else if (TM.getOptLevel() == CodeGenOptLevel::None &&
+           TM.getO0WantsFastISel())
+    Selector = SelectorType::FastISel;
+  else
+    Selector = SelectorType::SelectionDAG;
+
+  return Selector;
+}
+
 Expected<TargetPassConfig::StartStopInfo>
 TargetPassConfig::getStartStopInfo(PassInstrumentationCallbacks &PIC) {
   auto [StartBefore, StartBeforeInstanceNum] =
@@ -990,20 +1007,7 @@ bool TargetPassConfig::addCoreISelPasses() {
   TM->setO0WantsFastISel(EnableFastISelOption != cl::BOU_FALSE);
 
   // Determine an instruction selector.
-  enum class SelectorType { SelectionDAG, FastISel, GlobalISel };
-  SelectorType Selector;
-
-  if (EnableFastISelOption == cl::BOU_TRUE)
-    Selector = SelectorType::FastISel;
-  else if (EnableGlobalISelOption == cl::BOU_TRUE ||
-           (TM->Options.EnableGlobalISel &&
-            EnableGlobalISelOption != cl::BOU_FALSE))
-    Selector = SelectorType::GlobalISel;
-  else if (TM->getOptLevel() == CodeGenOptLevel::None &&
-           TM->getO0WantsFastISel())
-    Selector = SelectorType::FastISel;
-  else
-    Selector = SelectorType::SelectionDAG;
+  SelectorType Selector = getSelectorType(*TM);
 
   // Set consistently TM->Options.EnableFastISel and EnableGlobalISel.
   if (Selector == SelectorType::FastISel) {

llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

@@ -751,7 +751,10 @@ AMDGPUTargetMachine::AMDGPUTargetMachine(const Target &T, const Triple &TT,
           getEffectiveCodeModel(CM, CodeModel::Small), OptLevel),
       TLOF(createTLOF(getTargetTriple())) {
   initAsmInfo();
-  setNewPMForBackend(true);
+
+  if (getSelectorType(*this) != SelectorType::GlobalISel)
+    setNewPMForBackend(true);
+
   if (TT.isAMDGCN()) {
     if (getMCSubtargetInfo()->checkFeatures("+wavefrontsize64"))
       MRI.reset(llvm::createGCNMCRegisterInfo(AMDGPUDwarfFlavour::Wave64));