[TableGen][MC] Pass a MCSubtargetInfo instance into resolveVariantSchedClassImpl (#161886)

`Target_MC::resolveVariantSchedClassImpl` is the implementation function for `TargetGenMCSubtargetInfo::resolveVariantSchedClass`. Despite being only called by `resolveVariantSchedClass`, `resolveVariantSchedClassImpl` is still a standalone function that cannot access a MCSubtargetInfo through `this` (i.e. `TargetGenMCSubtargetInfo`). And having access to a `MCSubtargetInfo` could be useful for some (future) SchedPredicate. This patch modifies TableGen to generate `resolveVariantSchedClassImpl` with an additional `MCSubtargetInfo` argument passing in. Note that this does not change any public interface in either `TargetGenMCSubtargetInfo ` or `MCSubtargetInfo`, as `resolveVariantSchedClassImpl` is basically an internal function.

Author: mshockwave

llvm/test/TableGen/ResolveSchedClass.td

@@ -0,0 +1,18 @@
+// RUN: llvm-tblgen -gen-subtarget -I %p/../../include %s -o - | FileCheck %s
+
+include "llvm/Target/Target.td"
+
+def TestTargetInstrInfo : InstrInfo;
+
+def TestTarget : Target {
+ let InstructionSet = TestTargetInstrInfo;
+}
+
+// CHECK: unsigned resolveVariantSchedClassImpl(unsigned SchedClass,
+// CHECK-NEXT: const MCInst *MI, const MCInstrInfo *MCII, const MCSubtargetInfo &STI, unsigned CPUID)
+
+// CHECK: unsigned resolveVariantSchedClass(unsigned SchedClass,
+// CHECK-NEXT: const MCInst *MI, const MCInstrInfo *MCII,
+// CHECK-NEXT: unsigned CPUID) const override {
+// CHECK-NEXT: return TestTarget_MC::resolveVariantSchedClassImpl(SchedClass, MI, MCII, *this, CPUID);
+// CHECK-NEXT: }

llvm/utils/TableGen/SubtargetEmitter.cpp

@@ -1761,7 +1761,7 @@ void SubtargetEmitter::emitSchedModelHelpers(const std::string &ClassName,
  << "\n::resolveVariantSchedClass(unsigned SchedClass, const MCInst *MI,"
  << " const MCInstrInfo *MCII, unsigned CPUID) const {\n"
  << " return " << Target << "_MC"
- << "::resolveVariantSchedClassImpl(SchedClass, MI, MCII, CPUID);\n"
+ << "::resolveVariantSchedClassImpl(SchedClass, MI, MCII, *this, CPUID);\n"
  << "} // " << ClassName << "::resolveVariantSchedClass\n\n";
 
  STIPredicateExpander PE(Target, /*Indent=*/0);
@@ -1923,7 +1923,8 @@ void SubtargetEmitter::parseFeaturesFunction(raw_ostream &OS) {
 void SubtargetEmitter::emitGenMCSubtargetInfo(raw_ostream &OS) {
  OS << "namespace " << Target << "_MC {\n"
  << "unsigned resolveVariantSchedClassImpl(unsigned SchedClass,\n"
- << " const MCInst *MI, const MCInstrInfo *MCII, unsigned CPUID) {\n";
+ << " const MCInst *MI, const MCInstrInfo *MCII, "
+ << "const MCSubtargetInfo &STI, unsigned CPUID) {\n";
  emitSchedModelHelpersImpl(OS, /* OnlyExpandMCPredicates */ true);
  OS << "}\n";
  OS << "} // end namespace " << Target << "_MC\n\n";
@@ -1945,7 +1946,7 @@ void SubtargetEmitter::emitGenMCSubtargetInfo(raw_ostream &OS) {
  << " const MCInst *MI, const MCInstrInfo *MCII,\n"
  << " unsigned CPUID) const override {\n"
  << " return " << Target << "_MC"
- << "::resolveVariantSchedClassImpl(SchedClass, MI, MCII, CPUID);\n";
+ << "::resolveVariantSchedClassImpl(SchedClass, MI, MCII, *this, CPUID);\n";
  OS << " }\n";
  if (TGT.getHwModes().getNumModeIds() > 1) {
  OS << " unsigned getHwModeSet() const override;\n";
@@ -2073,7 +2074,8 @@ void SubtargetEmitter::run(raw_ostream &OS) {
  OS << "class DFAPacketizer;\n";
  OS << "namespace " << Target << "_MC {\n"
  << "unsigned resolveVariantSchedClassImpl(unsigned SchedClass,"
- << " const MCInst *MI, const MCInstrInfo *MCII, unsigned CPUID);\n"
+ << " const MCInst *MI, const MCInstrInfo *MCII, "
+ << "const MCSubtargetInfo &STI, unsigned CPUID);\n"
  << "} // end namespace " << Target << "_MC\n\n";
  OS << "struct " << ClassName << " : public TargetSubtargetInfo {\n"
  << " explicit " << ClassName << "(const Triple &TT, StringRef CPU, "