commit 11c9a325399b282cb4ea7d1d24d42fceeec2a09a
author Andrew Scull <ascull@google.com> Fri Aug 28 14:24:14 2015 -0700
committer Andrew Scull <ascull@google.com> Fri Aug 28 14:24:14 2015 -0700
tree 351ff0336a0789b72500fde2c83a9426a4e9ba3a
parent 25529f7bdaf3dfa08455b87642a120e84961d6d6

Weight variables for register allocation by their number of uses.

Count the number of instructions that use a variable following the heuristic
that more uses implies higher register priority. This is currently very simple
but is precursor work for weighting variables by loop nest depth.

BUG=
R=jvoung@chromium.org

Review URL: https://codereview.chromium.org/1312433004.

src/IceTargetLoweringARM32.cpp

diff --git a/src/IceTargetLoweringARM32.cpp b/src/IceTargetLoweringARM32.cpp
index c3d05a2..9b10eff 100644
--- a/src/IceTargetLoweringARM32.cpp
+++ b/src/IceTargetLoweringARM32.cpp
@@ -410,7 +410,7 @@
     Str << getRegName(Var->getRegNum(), Var->getType());
     return;
   }
-  if (Var->getWeight().isInf()) {
+  if (Var->mustHaveReg()) {
     llvm::report_fatal_error(
         "Infinite-weight Variable has no register assigned");
   }
@@ -907,7 +907,7 @@
   else
     _add(ScratchReg, OrigBaseReg, OffsetVal);
   StackVariable *NewVar = Func->makeVariable<StackVariable>(stackSlotType());
-  NewVar->setWeight(RegWeight::Zero);
+  NewVar->setMustNotHaveReg();
   NewVar->setBaseRegNum(ScratchReg->getRegNum());
   constexpr int32_t NewOffset = 0;
   NewVar->setStackOffset(NewOffset);
@@ -984,7 +984,7 @@
             if (isLegalVariableStackOffset(OffsetDiff)) {
               StackVariable *NewDest =
                   Func->makeVariable<StackVariable>(stackSlotType());
-              NewDest->setWeight(RegWeight::Zero);
+              NewDest->setMustNotHaveReg();
               NewDest->setBaseRegNum(NewBaseReg->getBaseRegNum());
               NewDest->setStackOffset(OffsetDiff);
               Variable *NewDestVar = NewDest;
@@ -1014,7 +1014,7 @@
             if (isLegalVariableStackOffset(OffsetDiff)) {
               StackVariable *NewVar =
                   Func->makeVariable<StackVariable>(stackSlotType());
-              NewVar->setWeight(RegWeight::Zero);
+              NewVar->setMustNotHaveReg();
               NewVar->setBaseRegNum(NewBaseReg->getBaseRegNum());
               NewVar->setStackOffset(OffsetDiff);
               _mov(Dest, NewVar);
@@ -2834,7 +2834,7 @@
     // Check if the variable is guaranteed a physical register.  This
     // can happen either when the variable is pre-colored or when it is
     // assigned infinite weight.
-    bool MustHaveRegister = (Var->hasReg() || Var->getWeight().isInf());
+    bool MustHaveRegister = (Var->hasReg() || Var->mustHaveReg());
     // We need a new physical register for the operand if:
     //   Mem is not allowed and Var isn't guaranteed a physical
     //   register, or
@@ -2899,7 +2899,7 @@
   assert(Type != IceType_i64);
   Variable *Reg = Func->makeVariable(Type);
   if (RegNum == Variable::NoRegister)
-    Reg->setWeightInfinite();
+    Reg->setMustHaveReg();
   else
     Reg->setRegNum(RegNum);
   return Reg;