Let tablegen compute maximum lanemask for regs/regclasses.

Let tablegen compute the combination of subregister lanemasks for all
subregisters in a register/register class. This is preparation for further
work subregister allocation

llvm-svn: 223873

1 files changed, 15 insertions, 3 deletions

diff --git a/llvm/utils/TableGen/CodeGenRegisters.cpp b/llvm/utils/TableGen/CodeGenRegisters.cpp
index c50ed9b..fdfdba4 100644
--- a/llvm/utils/TableGen/CodeGenRegisters.cpp
+++ b/llvm/utils/TableGen/CodeGenRegisters.cpp
@@ -661,7 +661,8 @@ CodeGenRegisterClass::CodeGenRegisterClass(CodeGenRegBank &RegBank, Record *R)
   : TheDef(R),
     Name(R->getName()),
     TopoSigs(RegBank.getNumTopoSigs()),
-    EnumValue(-1) {
+    EnumValue(-1),
+    LaneMask(0) {
   // Rename anonymous register classes.
   if (R->getName().size() > 9 && R->getName()[9] == '.') {
     static unsigned AnonCounter = 0;
@@ -1165,7 +1166,7 @@ void CodeGenRegBank::computeComposites() {
 //
 // Conservatively share a lane mask bit if two sub-register indices overlap in
 // some registers, but not in others. That shouldn't happen a lot.
-void CodeGenRegBank::computeSubRegIndexLaneMasks() {
+void CodeGenRegBank::computeSubRegLaneMasks() {
   // First assign individual bits to all the leaf indices.
   unsigned Bit = 0;
   // Determine mask of lanes that cover their registers.
@@ -1202,6 +1203,17 @@ void CodeGenRegBank::computeSubRegIndexLaneMasks() {
     if (!Idx.AllSuperRegsCovered)
       CoveringLanes &= ~Mask;
   }
+
+  // Compute lane mask combinations for register classes.
+  for (auto &RegClass : RegClasses) {
+    unsigned LaneMask = 0;
+    for (const auto &SubRegIndex : SubRegIndices) {
+      if (RegClass.getSubClassWithSubReg(&SubRegIndex) != &RegClass)
+        continue;
+      LaneMask |= SubRegIndex.LaneMask;
+    }
+    RegClass.LaneMask = LaneMask;
+  }
 }
 
 namespace {
@@ -1689,7 +1701,7 @@ void CodeGenRegBank::computeRegUnitSets() {
 
 void CodeGenRegBank::computeDerivedInfo() {
   computeComposites();
-  computeSubRegIndexLaneMasks();
+  computeSubRegLaneMasks();
 
   // Compute a weight for each register unit created during getSubRegs.
   // This may create adopted register units (with unit # >= NumNativeRegUnits).