From: Dan Gohman <gohman@apple.com>
Date: Sat, 26 Sep 2009 02:34:00 +0000 (+0000)
Subject: Don't hoist or sink instructions with physreg uses if the physreg is
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=45094e34bcbb133aa0bbe55710e25369df0e02ed;p=oota-llvm.git

Don't hoist or sink instructions with physreg uses if the physreg is
allocatable. Even if it doesn't appear to have any defs, it may latter
on after register allocation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82834 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp
index 8123d99680b..61678f1d7c6 100644
--- a/lib/CodeGen/MachineLICM.cpp
+++ b/lib/CodeGen/MachineLICM.cpp
@@ -44,6 +44,7 @@ namespace {
     const TargetMachine   *TM;
     const TargetInstrInfo *TII;
     const TargetRegisterInfo *TRI;
+    BitVector AllocatableSet;
 
     // Various analyses that we use...
     MachineLoopInfo      *LI;      // Current MachineLoopInfo
@@ -138,6 +139,7 @@ bool MachineLICM::runOnMachineFunction(MachineFunction &MF) {
   TII = TM->getInstrInfo();
   TRI = TM->getRegisterInfo();
   RegInfo = &MF.getRegInfo();
+  AllocatableSet = TRI->getAllocatableSet(MF);
 
   // Get our Loop information...
   LI = &getAnalysis<MachineLoopInfo>();
@@ -261,13 +263,20 @@ bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) {
       // we can move it, but only if the def is dead.
       if (MO.isUse()) {
         // If the physreg has no defs anywhere, it's just an ambient register
-        // and we can freely move its uses.
+        // and we can freely move its uses. Alternatively, if it's allocatable,
+        // it could get allocated to something with a def during allocation.
         if (!RegInfo->def_empty(Reg))
           return false;
+        if (AllocatableSet.test(Reg))
+          return false;
         // Check for a def among the register's aliases too.
-        for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias)
-          if (!RegInfo->def_empty(*Alias))
+        for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
+          unsigned AliasReg = *Alias;
+          if (!RegInfo->def_empty(AliasReg))
+            return false;
+          if (AllocatableSet.test(AliasReg))
             return false;
+        }
         // Otherwise it's safe to move.
         continue;
       } else if (!MO.isDead()) {
diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index 5f555b2f631..636dad8ffb9 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -39,6 +39,7 @@ namespace {
     MachineFunction       *CurMF; // Current MachineFunction
     MachineRegisterInfo  *RegInfo; // Machine register information
     MachineDominatorTree *DT;   // Machine dominator tree
+    BitVector AllocatableSet;   // Which physregs are allocatable?
 
   public:
     static char ID; // Pass identification
@@ -99,6 +100,7 @@ bool MachineSinking::runOnMachineFunction(MachineFunction &MF) {
   TRI = TM->getRegisterInfo();
   RegInfo = &CurMF->getRegInfo();
   DT = &getAnalysis<MachineDominatorTree>();
+  AllocatableSet = TRI->getAllocatableSet(*CurMF);
 
   bool EverMadeChange = false;
   
@@ -180,13 +182,20 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
       // we can move it, but only if the def is dead.
       if (MO.isUse()) {
         // If the physreg has no defs anywhere, it's just an ambient register
-        // and we can freely move its uses.
+        // and we can freely move its uses. Alternatively, if it's allocatable,
+        // it could get allocated to something with a def during allocation.
         if (!RegInfo->def_empty(Reg))
           return false;
+        if (AllocatableSet.test(Reg))
+          return false;
         // Check for a def among the register's aliases too.
-        for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias)
-          if (!RegInfo->def_empty(*Alias))
+        for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
+          unsigned AliasReg = *Alias;
+          if (!RegInfo->def_empty(AliasReg))
+            return false;
+          if (AllocatableSet.test(AliasReg))
             return false;
+        }
       } else if (!MO.isDead()) {
         // A def that isn't dead. We can't move it.
         return false;