[llvm][X86ISelDAGToDAG] support -{start|stop}-{before|after}=x86-isel

Follow a similar pattern as AMDGPUDAGToDAGISel's constructor so that we
can use INITIALIZE_PASS to register a pass. This allows for more fine
grain testability of SelectionDAGISel.

Link: llvm/llvm-project#59538

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D140323

Author: nickdesaulniers

llvm/lib/Target/X86/X86.h

@@ -164,35 +164,36 @@ FunctionPass *createX86SpeculativeLoadHardeningPass();
 FunctionPass *createX86SpeculativeExecutionSideEffectSuppression();
 
 void initializeEvexToVexInstPassPass(PassRegistry &);
+void initializeFPSPass(PassRegistry &);
 void initializeFixupBWInstPassPass(PassRegistry &);
 void initializeFixupLEAPassPass(PassRegistry &);
-void initializeFPSPass(PassRegistry &);
 void initializeWinEHStatePassPass(PassRegistry &);
 void initializeX86AvoidSFBPassPass(PassRegistry &);
 void initializeX86AvoidTrailingCallPassPass(PassRegistry &);
 void initializeX86CallFrameOptimizationPass(PassRegistry &);
 void initializeX86CmovConverterPassPass(PassRegistry &);
+void initializeX86DAGToDAGISelPass(PassRegistry &);
 void initializeX86DomainReassignmentPass(PassRegistry &);
 void initializeX86ExecutionDomainFixPass(PassRegistry &);
 void initializeX86ExpandPseudoPass(PassRegistry &);
+void initializeX86FastPreTileConfigPass(PassRegistry &);
+void initializeX86FastTileConfigPass(PassRegistry &);
 void initializeX86FixupSetCCPassPass(PassRegistry &);
 void initializeX86FlagsCopyLoweringPassPass(PassRegistry &);
 void initializeX86KCFIPass(PassRegistry &);
 void initializeX86LoadValueInjectionLoadHardeningPassPass(PassRegistry &);
 void initializeX86LoadValueInjectionRetHardeningPassPass(PassRegistry &);
+void initializeX86LowerAMXIntrinsicsLegacyPassPass(PassRegistry &);
+void initializeX86LowerAMXTypeLegacyPassPass(PassRegistry &);
+void initializeX86LowerTileCopyPass(PassRegistry &);
 void initializeX86OptimizeLEAPassPass(PassRegistry &);
 void initializeX86PartialReductionPass(PassRegistry &);
-void initializeX86SpeculativeLoadHardeningPassPass(PassRegistry &);
-void initializeX86SpeculativeExecutionSideEffectSuppressionPass(PassRegistry &);
-void initializeX86PreTileConfigPass(PassRegistry &);
-void initializeX86FastPreTileConfigPass(PassRegistry &);
-void initializeX86FastTileConfigPass(PassRegistry &);
-void initializeX86TileConfigPass(PassRegistry &);
-void initializeX86LowerAMXTypeLegacyPassPass(PassRegistry &);
 void initializeX86PreAMXConfigPassPass(PassRegistry &);
-void initializeX86LowerTileCopyPass(PassRegistry &);
-void initializeX86LowerAMXIntrinsicsLegacyPassPass(PassRegistry &);
+void initializeX86PreTileConfigPass(PassRegistry &);
 void initializeX86ReturnThunksPass(PassRegistry &);
+void initializeX86SpeculativeExecutionSideEffectSuppressionPass(PassRegistry &);
+void initializeX86SpeculativeLoadHardeningPassPass(PassRegistry &);
+void initializeX86TileConfigPass(PassRegistry &);
 
 namespace X86AS {
 enum : unsigned {

llvm/lib/Target/X86/X86ISelDAGToDAG.cpp

@@ -35,6 +35,7 @@
 using namespace llvm;
 
 #define DEBUG_TYPE "x86-isel"
+#define PASS_NAME "X86 DAG->DAG Instruction Selection"
 
 STATISTIC(NumLoadMoved, "Number of loads moved below TokenFactor");
 
@@ -176,10 +177,6 @@ namespace {
         : SelectionDAGISel(ID, tm, OptLevel), Subtarget(nullptr),
           OptForMinSize(false), IndirectTlsSegRefs(false) {}
 
-    StringRef getPassName() const override {
-      return "X86 DAG->DAG Instruction Selection";
-    }
-
     bool runOnMachineFunction(MachineFunction &MF) override {
       // Reset the subtarget each time through.
       Subtarget = &MF.getSubtarget<X86Subtarget>();
@@ -580,6 +577,8 @@ namespace {
 
 char X86DAGToDAGISel::ID = 0;
 
+INITIALIZE_PASS(X86DAGToDAGISel, DEBUG_TYPE, PASS_NAME, false, false)
+
 // Returns true if this masked compare can be implemented legally with this
 // type.
 static bool isLegalMaskCompare(SDNode *N, const X86Subtarget *Subtarget) {

llvm/lib/Target/X86/X86TargetMachine.cpp

@@ -102,6 +102,7 @@ extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeX86Target() {
   initializeX86PartialReductionPass(PR);
   initializePseudoProbeInserterPass(PR);
   initializeX86ReturnThunksPass(PR);
+  initializeX86DAGToDAGISelPass(PR);
 }
 
 static std::unique_ptr<TargetLoweringObjectFile> createTLOF(const Triple &TT) {