From 3731bc026cc6c4fb7deb7ac67e2c3be0c22498be Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Sat, 10 Oct 2009 00:34:18 +0000
Subject: [PATCH] Replace X86's CanRematLoadWithDispOperand by calling the
 target-independent MachineInstr::isInvariantLoad instead, which has the
 benefit of being more complete.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83696 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Target/TargetInstrInfo.h |  5 +++--
 lib/Target/X86/X86InstrInfo.cpp       | 28 +++------------------------
 lib/Target/X86/X86InstrInfo.h         |  3 ++-
 3 files changed, 8 insertions(+), 28 deletions(-)

diff --git a/include/llvm/Target/TargetInstrInfo.h b/include/llvm/Target/TargetInstrInfo.h
index 8070c7d08e7..5cd6ff5082e 100644
--- a/include/llvm/Target/TargetInstrInfo.h
+++ b/include/llvm/Target/TargetInstrInfo.h
@@ -107,7 +107,7 @@ public:
                                    AliasAnalysis *AA = 0) const {
     return MI->getOpcode() == IMPLICIT_DEF ||
            (MI->getDesc().isRematerializable() &&
-            (isReallyTriviallyReMaterializable(MI) ||
+            (isReallyTriviallyReMaterializable(MI, AA) ||
              isReallyTriviallyReMaterializableGeneric(MI, AA)));
   }
 
@@ -118,7 +118,8 @@ protected:
   /// taking into consideration its operands. This predicate must return false
   /// if the instruction has any side effects other than producing a value, or
   /// if it requres any address registers that are not always available.
-  virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI) const {
+  virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI,
+                                                 AliasAnalysis *AA) const {
     return false;
   }
 
diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index 6558df01421..56de6d9ab41 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -782,31 +782,9 @@ static bool regIsPICBase(unsigned BaseReg, const MachineRegisterInfo &MRI) {
   return isPICBase;
 }
 
-/// CanRematLoadWithDispOperand - Return true if a load with the specified
-/// operand is a candidate for remat: for this to be true we need to know that
-/// the load will always return the same value, even if moved.
-static bool CanRematLoadWithDispOperand(const MachineOperand &MO,
-                                        X86TargetMachine &TM) {
-  // Loads from constant pool entries can be remat'd.
-  if (MO.isCPI()) return true;
-  
-  // We can remat globals in some cases.
-  if (MO.isGlobal()) {
-    // If this is a load of a stub, not of the global, we can remat it.  This
-    // access will always return the address of the global.
-    if (isGlobalStubReference(MO.getTargetFlags()))
-      return true;
-    
-    // If the global itself is constant, we can remat the load.
-    if (GlobalVariable *GV = dyn_cast<GlobalVariable>(MO.getGlobal()))
-      if (GV->isConstant())
-        return true;
-  }
-  return false;
-}
- 
 bool
-X86InstrInfo::isReallyTriviallyReMaterializable(const MachineInstr *MI) const {
+X86InstrInfo::isReallyTriviallyReMaterializable(const MachineInstr *MI,
+                                                AliasAnalysis *AA) const {
   switch (MI->getOpcode()) {
   default: break;
     case X86::MOV8rm:
@@ -825,7 +803,7 @@ X86InstrInfo::isReallyTriviallyReMaterializable(const MachineInstr *MI) const {
       if (MI->getOperand(1).isReg() &&
           MI->getOperand(2).isImm() &&
           MI->getOperand(3).isReg() && MI->getOperand(3).getReg() == 0 &&
-          CanRematLoadWithDispOperand(MI->getOperand(4), TM)) {
+          MI->isInvariantLoad(AA)) {
         unsigned BaseReg = MI->getOperand(1).getReg();
         if (BaseReg == 0 || BaseReg == X86::RIP)
           return true;
diff --git a/lib/Target/X86/X86InstrInfo.h b/lib/Target/X86/X86InstrInfo.h
index 83162fb03d5..2237c8be517 100644
--- a/lib/Target/X86/X86InstrInfo.h
+++ b/lib/Target/X86/X86InstrInfo.h
@@ -451,7 +451,8 @@ public:
   unsigned isLoadFromStackSlot(const MachineInstr *MI, int &FrameIndex) const;
   unsigned isStoreToStackSlot(const MachineInstr *MI, int &FrameIndex) const;
 
-  bool isReallyTriviallyReMaterializable(const MachineInstr *MI) const;
+  bool isReallyTriviallyReMaterializable(const MachineInstr *MI,
+                                         AliasAnalysis *AA) const;
   void reMaterialize(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
                      unsigned DestReg, unsigned SubIdx,
                      const MachineInstr *Orig) const;
-- 
2.34.1