From: Jim Grosbach <grosbach@apple.com>
Date: Fri, 3 Sep 2010 21:45:15 +0000 (+0000)
Subject: previous patch was a little too tricky for its own good. Don't try to
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=ee72651df4b783c973bb682bef7eab2ff9a703e2;p=oota-llvm.git

previous patch was a little too tricky for its own good. Don't try to
overload UserInInstr. Explicitly check Allocatable. The early exit in the
condition will mean the performance impact of the extra test should be
minimal.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113016 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp
index 3cf1d726ecc..fc150d55e22 100644
--- a/lib/CodeGen/RegAllocFast.cpp
+++ b/lib/CodeGen/RegAllocFast.cpp
@@ -113,9 +113,6 @@ namespace {
     // Allocatable - vector of allocatable physical registers.
     BitVector Allocatable;
 
-    // Reserved - vector of reserved physical registers.
-    BitVector Reserved;
-
     // SkippedInstrs - Descriptors of instructions whose clobber list was
     // ignored because all registers were spilled. It is still necessary to
     // mark all the clobbered registers as used by the function.
@@ -501,7 +498,8 @@ void RAFast::allocVirtReg(MachineInstr *MI, LiveRegEntry &LRE, unsigned Hint) {
   // First try to find a completely free register.
   for (TargetRegisterClass::iterator I = AOB; I != AOE; ++I) {
     unsigned PhysReg = *I;
-    if (PhysRegState[PhysReg] == regFree && !UsedInInstr.test(PhysReg))
+    if (PhysRegState[PhysReg] == regFree && !UsedInInstr.test(PhysReg) &&
+        Allocatable.test(PhysReg))
       return assignVirtToPhysReg(LRE, PhysReg);
   }
 
@@ -510,6 +508,8 @@ void RAFast::allocVirtReg(MachineInstr *MI, LiveRegEntry &LRE, unsigned Hint) {
 
   unsigned BestReg = 0, BestCost = spillImpossible;
   for (TargetRegisterClass::iterator I = AOB; I != AOE; ++I) {
+    if (!Allocatable.test(*I))
+      continue;
     unsigned Cost = calcSpillCost(*I);
     // Cost is 0 when all aliases are already disabled.
     if (Cost == 0)
@@ -712,7 +712,7 @@ void RAFast::handleThroughOperands(MachineInstr *MI,
   }
 
   // Restore UsedInInstr to a state usable for allocating normal virtual uses.
-  UsedInInstr = Reserved;
+  UsedInInstr.reset();
   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
     MachineOperand &MO = MI->getOperand(i);
     if (!MO.isReg() || (MO.isDef() && !MO.isEarlyClobber())) continue;
@@ -838,7 +838,7 @@ void RAFast::AllocateBasicBlock() {
     }
 
     // Track registers used by instruction.
-    UsedInInstr = Reserved;
+    UsedInInstr.reset();
 
     // First scan.
     // Mark physreg uses and early clobbers as used.
@@ -916,7 +916,7 @@ void RAFast::AllocateBasicBlock() {
 
     // Track registers defined by instruction - early clobbers and tied uses at
     // this point.
-    UsedInInstr = Reserved;
+    UsedInInstr.reset();
     if (hasEarlyClobbers) {
       for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
         MachineOperand &MO = MI->getOperand(i);
@@ -1014,7 +1014,6 @@ bool RAFast::runOnMachineFunction(MachineFunction &Fn) {
 
   UsedInInstr.resize(TRI->getNumRegs());
   Allocatable = TRI->getAllocatableSet(*MF);
-  Reserved = TRI->getReservedRegs(*MF);
 
   // initialize the virtual->physical register map to have a 'null'
   // mapping for all virtual registers