[llvm] 2f23f5c - [CodeGen] Use delegate to notify targets when virtual registers are created

[Christudasan Devadasan via llvm-commits]

Author: Christudasan Devadasan
Date: 2022-12-17T11:53:34+05:30
New Revision: 2f23f5c0d53c619101541a348cd817174ac27783

URL: https://github.com/llvm/llvm-project/commit/2f23f5c0d53c619101541a348cd817174ac27783
DIFF: https://github.com/llvm/llvm-project/commit/2f23f5c0d53c619101541a348cd817174ac27783.diff

LOG: [CodeGen] Use delegate to notify targets when virtual registers are created

This will help targets to customize certain codegen decisions based on
the virtual registers involved in special operations. This patch also
extends the existing delegate in MRI to start support multicast.

Reviewed By: qcolombet

Differential Revision: https://reviews.llvm.org/D134950

Added: 
    

Modified: 
    llvm/include/llvm/CodeGen/LiveRangeEdit.h
    llvm/include/llvm/CodeGen/MachineRegisterInfo.h
    llvm/lib/CodeGen/MachineRegisterInfo.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/CodeGen/LiveRangeEdit.h b/llvm/include/llvm/CodeGen/LiveRangeEdit.h
index aaaf8ea5b0030..fedcff026be1f 100644
--- a/llvm/include/llvm/CodeGen/LiveRangeEdit.h
+++ b/llvm/include/llvm/CodeGen/LiveRangeEdit.h
@@ -133,7 +133,7 @@ class LiveRangeEdit : private MachineRegisterInfo::Delegate {
       : Parent(parent), NewRegs(newRegs), MRI(MF.getRegInfo()), LIS(lis),
         VRM(vrm), TII(*MF.getSubtarget().getInstrInfo()), TheDelegate(delegate),
         FirstNew(newRegs.size()), DeadRemats(deadRemats) {
-    MRI.setDelegate(this);
+    MRI.addDelegate(this);
   }
 
   ~LiveRangeEdit() override { MRI.resetDelegate(this); }

diff  --git a/llvm/include/llvm/CodeGen/MachineRegisterInfo.h b/llvm/include/llvm/CodeGen/MachineRegisterInfo.h
index 75a444f796567..572217213920d 100644
--- a/llvm/include/llvm/CodeGen/MachineRegisterInfo.h
+++ b/llvm/include/llvm/CodeGen/MachineRegisterInfo.h
@@ -17,6 +17,7 @@
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/IndexedMap.h"
 #include "llvm/ADT/PointerUnion.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/iterator_range.h"
@@ -56,11 +57,15 @@ class MachineRegisterInfo {
     virtual ~Delegate() = default;
 
     virtual void MRI_NoteNewVirtualRegister(Register Reg) = 0;
+    virtual void MRI_NotecloneVirtualRegister(Register NewReg,
+                                              Register SrcReg) {
+      MRI_NoteNewVirtualRegister(NewReg);
+    }
   };
 
 private:
   MachineFunction *MF;
-  Delegate *TheDelegate = nullptr;
+  SmallPtrSet<Delegate *, 1> TheDelegates;
 
   /// True if subregister liveness is tracked.
   const bool TracksSubRegLiveness;
@@ -154,19 +159,28 @@ class MachineRegisterInfo {
 
   void resetDelegate(Delegate *delegate) {
     // Ensure another delegate does not take over unless the current
-    // delegate first unattaches itself. If we ever need to multicast
-    // notifications, we will need to change to using a list.
-    assert(TheDelegate == delegate &&
-           "Only the current delegate can perform reset!");
-    TheDelegate = nullptr;
+    // delegate first unattaches itself.
+    assert(TheDelegates.count(delegate) &&
+           "Only an existing delegate can perform reset!");
+    TheDelegates.erase(delegate);
   }
 
-  void setDelegate(Delegate *delegate) {
-    assert(delegate && !TheDelegate &&
-           "Attempted to set delegate to null, or to change it without "
+  void addDelegate(Delegate *delegate) {
+    assert(delegate && !TheDelegates.count(delegate) &&
+           "Attempted to add null delegate, or to change it without "
            "first resetting it!");
 
-    TheDelegate = delegate;
+    TheDelegates.insert(delegate);
+  }
+
+  void noteNewVirtualRegister(Register Reg) {
+    for (auto *TheDelegate : TheDelegates)
+      TheDelegate->MRI_NoteNewVirtualRegister(Reg);
+  }
+
+  void noteCloneVirtualRegister(Register NewReg, Register SrcReg) {
+    for (auto *TheDelegate : TheDelegates)
+      TheDelegate->MRI_NotecloneVirtualRegister(NewReg, SrcReg);
   }
 
   //===--------------------------------------------------------------------===//

diff  --git a/llvm/lib/CodeGen/MachineRegisterInfo.cpp b/llvm/lib/CodeGen/MachineRegisterInfo.cpp
index e322250460d5a..5a7d43222610d 100644
--- a/llvm/lib/CodeGen/MachineRegisterInfo.cpp
+++ b/llvm/lib/CodeGen/MachineRegisterInfo.cpp
@@ -48,6 +48,7 @@ MachineRegisterInfo::MachineRegisterInfo(MachineFunction *MF)
   RegAllocHints.reserve(256);
   UsedPhysRegMask.resize(NumRegs);
   PhysRegUseDefLists.reset(new MachineOperand*[NumRegs]());
+  TheDelegates.clear();
 }
 
 /// setRegClass - Set the register class of the specified virtual register.
@@ -162,8 +163,7 @@ MachineRegisterInfo::createVirtualRegister(const TargetRegisterClass *RegClass,
   // New virtual register number.
   Register Reg = createIncompleteVirtualRegister(Name);
   VRegInfo[Reg].first = RegClass;
-  if (TheDelegate)
-    TheDelegate->MRI_NoteNewVirtualRegister(Reg);
+  noteNewVirtualRegister(Reg);
   return Reg;
 }
 
@@ -172,8 +172,7 @@ Register MachineRegisterInfo::cloneVirtualRegister(Register VReg,
   Register Reg = createIncompleteVirtualRegister(Name);
   VRegInfo[Reg].first = VRegInfo[VReg].first;
   setType(Reg, getType(VReg));
-  if (TheDelegate)
-    TheDelegate->MRI_NoteNewVirtualRegister(Reg);
+  noteCloneVirtualRegister(Reg, VReg);
   return Reg;
 }
 
@@ -189,8 +188,7 @@ MachineRegisterInfo::createGenericVirtualRegister(LLT Ty, StringRef Name) {
   // FIXME: Should we use a dummy register class?
   VRegInfo[Reg].first = static_cast<RegisterBank *>(nullptr);
   setType(Reg, Ty);
-  if (TheDelegate)
-    TheDelegate->MRI_NoteNewVirtualRegister(Reg);
+  noteNewVirtualRegister(Reg);
   return Reg;
 }