1 files changed, 18 insertions, 15 deletions
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 1ca2d46..3680943 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -28,6 +28,7 @@
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/VirtRegMap.h"
 #include "llvm/IR/Value.h"
+#include "llvm/Support/BlockFrequency.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -51,6 +52,14 @@ INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
 INITIALIZE_PASS_END(LiveIntervals, "liveintervals",
                 "Live Interval Analysis", false, false)
 
+#ifndef NDEBUG
+static cl::opt<bool> EnablePrecomputePhysRegs(
+  "precompute-phys-liveness", cl::Hidden,
+  cl::desc("Eagerly compute live intervals for all physreg units."));
+#else
+static bool EnablePrecomputePhysRegs = false;
+#endif // NDEBUG
+
 void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesCFG();
   AU.addRequired<AliasAnalysis>();
@@ -115,6 +124,12 @@ bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
   computeRegMasks();
   computeLiveInRegUnits();
 
+  if (EnablePrecomputePhysRegs) {
+    // For stress testing, precompute live ranges of all physical register
+    // units, including reserved registers.
+    for (unsigned i = 0, e = TRI->getNumRegUnits(); i != e; ++i)
+      getRegUnit(i);
+  }
   DEBUG(dump());
   return true;
 }
@@ -605,21 +620,9 @@ LiveIntervals::hasPHIKill(const LiveInterval &LI, const VNInfo *VNI) const {
 }
 
 float
-LiveIntervals::getSpillWeight(bool isDef, bool isUse, unsigned loopDepth) {
-  // Limit the loop depth ridiculousness.
-  if (loopDepth > 200)
-    loopDepth = 200;
-
-  // The loop depth is used to roughly estimate the number of times the
-  // instruction is executed. Something like 10^d is simple, but will quickly
-  // overflow a float. This expression behaves like 10^d for small d, but is
-  // more tempered for large d. At d=200 we get 6.7e33 which leaves a bit of
-  // headroom before overflow.
-  // By the way, powf() might be unavailable here. For consistency,
-  // We may take pow(double,double).
-  float lc = std::pow(1 + (100.0 / (loopDepth + 10)), (double)loopDepth);
-
-  return (isDef + isUse) * lc;
+LiveIntervals::getSpillWeight(bool isDef, bool isUse, BlockFrequency freq) {
+  const float Scale = 1.0f / BlockFrequency::getEntryFrequency();
+  return (isDef + isUse) * (freq.getFrequency() * Scale);
 }
 
 LiveRange LiveIntervals::addLiveRangeToEndOfBlock(unsigned reg,