[llvm-mca] Cleanup unnecessary includes from headers

This removes some includes/forward-declarations that don't seem to be necessary in the MCA core headers

Based off a cppclean report

Differential Revision: https://reviews.llvm.org/D77073

llvm/include/llvm/MCA/CodeEmitter.h

@@ -20,11 +20,8 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCCodeEmitter.h"
-#include "llvm/MC/MCFixup.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCSubtargetInfo.h"
-#include "llvm/MCA/Instruction.h"
-#include "llvm/MCA/Support.h"
 #include "llvm/Support/raw_ostream.h"
 
 #include <string>

llvm/include/llvm/MCA/HardwareUnits/LSUnit.h

@@ -24,8 +24,6 @@
 namespace llvm {
 namespace mca {
 
-class Scheduler;
-
 /// A node of a memory dependency graph. A MemoryGroup describes a set of
 /// instructions with same memory dependencies.
 ///

llvm/include/llvm/MCA/HardwareUnits/RegisterFile.h

@@ -22,7 +22,6 @@
 #include "llvm/MC/MCSchedule.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MCA/HardwareUnits/HardwareUnit.h"
-#include "llvm/Support/Error.h"
 
 namespace llvm {
 namespace mca {

llvm/include/llvm/MCA/HardwareUnits/ResourceManager.h

@@ -15,7 +15,6 @@
 #ifndef LLVM_MCA_RESOURCE_MANAGER_H
 #define LLVM_MCA_RESOURCE_MANAGER_H
 
-#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/MC/MCSchedule.h"

llvm/include/llvm/MCA/Pipeline.h

@@ -15,8 +15,6 @@
 #ifndef LLVM_MCA_PIPELINE_H
 #define LLVM_MCA_PIPELINE_H
 
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/MCA/HardwareUnits/Scheduler.h"
 #include "llvm/MCA/Stages/Stage.h"
 #include "llvm/Support/Error.h"
 

llvm/include/llvm/MCA/Stages/DispatchStage.h

@@ -20,7 +20,6 @@
 
 #include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/MC/MCSubtargetInfo.h"
-#include "llvm/MCA/HWEventListener.h"
 #include "llvm/MCA/HardwareUnits/RegisterFile.h"
 #include "llvm/MCA/HardwareUnits/RetireControlUnit.h"
 #include "llvm/MCA/Instruction.h"