RegisterPressure API. Add support for physical register units.

At build-time register pressure was always computed in terms of
register units. But the compile-time API was expressed in terms of
register classes because it was intended for virtual registers (and
physical register units weren't yet used anywhere in codegen).

Now that the codegen uses physreg units consistently, prepare for
tracking register pressure also in terms of live units, not live
registers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169360 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 16 insertions, 1 deletions

diff --git a/utils/TableGen/CodeGenRegisters.h b/utils/TableGen/CodeGenRegisters.h
index 8f85b0874b..a1921a412a 100644
--- a/utils/TableGen/CodeGenRegisters.h
+++ b/utils/TableGen/CodeGenRegisters.h
@@ -403,7 +403,11 @@ namespace llvm {
     // these two registers and their super-registers.
     const CodeGenRegister *Roots[2];
 
-    RegUnit() : Weight(0) { Roots[0] = Roots[1] = 0; }
+    // Index into RegClassUnitSets where we can find the list of UnitSets that
+    // contain this unit.
+    unsigned RegClassUnitSetsIdx;
+
+    RegUnit() : Weight(0), RegClassUnitSetsIdx(0) { Roots[0] = Roots[1] = 0; }
 
     ArrayRef<const CodeGenRegister*> getRoots() const {
       assert(!(Roots[1] && !Roots[0]) && "Invalid roots array");
@@ -462,6 +466,10 @@ namespace llvm {
 
     // Map RegisterClass index to the index of the RegUnitSet that contains the
     // class's units and any inferred RegUnit supersets.
+    //
+    // NOTE: This could grow beyond the number of register classes when we map
+    // register units to lists of unit sets. If the list of unit sets does not
+    // already exist for a register class, we create a new entry in this vector.
     std::vector<std::vector<unsigned> > RegClassUnitSets;
 
     // Add RC to *2RC maps.
@@ -615,6 +623,13 @@ namespace llvm {
       return RegUnitSets[Idx];
     }
 
+    // The number of pressure set lists may be larget than the number of
+    // register classes if some register units appeared in a list of sets that
+    // did not correspond to an existing register class.
+    unsigned getNumRegClassPressureSetLists() const {
+      return RegClassUnitSets.size();
+    }
+
     // Get a list of pressure set IDs for a register class. Liveness of a
     // register in this class impacts each pressure set in this list by the
     // weight of the register. An exact solution requires all registers in a