From: Matthias Braun <matze@braunis.de>
Date: Tue, 1 Dec 2015 04:20:04 +0000 (+0000)
Subject: RegisterPressure: Remove support for recede()/advance() at MBB boundaries
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=bce24cfb9ee40462a5fdc09503dfd3305e45326c;p=oota-llvm.git

RegisterPressure: Remove support for recede()/advance() at MBB boundaries

Nobody was checking the returnvalue of recede()/advance() so we can
simply replace this code with asserts.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254371 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/CodeGen/RegisterPressure.h b/include/llvm/CodeGen/RegisterPressure.h
index 42131c831ea..e296701d8e8 100644
--- a/include/llvm/CodeGen/RegisterPressure.h
+++ b/include/llvm/CodeGen/RegisterPressure.h
@@ -329,11 +329,11 @@ public:
   void setPos(MachineBasicBlock::const_iterator Pos) { CurrPos = Pos; }
 
   /// Recede across the previous instruction.
-  bool recede(SmallVectorImpl<unsigned> *LiveUses = nullptr,
+  void recede(SmallVectorImpl<unsigned> *LiveUses = nullptr,
               PressureDiff *PDiff = nullptr);
 
   /// Advance across the current instruction.
-  bool advance();
+  void advance();
 
   /// Finalize the region boundaries and recored live ins and live outs.
   void closeRegion();
@@ -350,8 +350,7 @@ public:
   ArrayRef<unsigned> getLiveThru() const { return LiveThruPressure; }
 
   /// Get the resulting register pressure over the traversed region.
-  /// This result is complete if either advance() or recede() has returned true,
-  /// or if closeRegion() was explicitly invoked.
+  /// This result is complete if closeRegion() was explicitly invoked.
   RegisterPressure &getPressure() { return P; }
   const RegisterPressure &getPressure() const { return P; }
 
diff --git a/lib/CodeGen/RegisterPressure.cpp b/lib/CodeGen/RegisterPressure.cpp
index 3c9da13c4a3..18002c8fbd5 100644
--- a/lib/CodeGen/RegisterPressure.cpp
+++ b/lib/CodeGen/RegisterPressure.cpp
@@ -491,13 +491,9 @@ void RegPressureTracker::discoverLiveOut(unsigned Reg) {
 /// registers that are both defined and used by the instruction.  If a pressure
 /// difference pointer is provided record the changes is pressure caused by this
 /// instruction independent of liveness.
-bool RegPressureTracker::recede(SmallVectorImpl<unsigned> *LiveUses,
+void RegPressureTracker::recede(SmallVectorImpl<unsigned> *LiveUses,
                                 PressureDiff *PDiff) {
-  // Check for the top of the analyzable region.
-  if (CurrPos == MBB->begin()) {
-    closeRegion();
-    return false;
-  }
+  assert(CurrPos != MBB->begin());
   if (!isBottomClosed())
     closeBottom();
 
@@ -509,11 +505,8 @@ bool RegPressureTracker::recede(SmallVectorImpl<unsigned> *LiveUses,
   do
     --CurrPos;
   while (CurrPos != MBB->begin() && CurrPos->isDebugValue());
+  assert(!CurrPos->isDebugValue());
 
-  if (CurrPos->isDebugValue()) {
-    closeRegion();
-    return false;
-  }
   SlotIndex SlotIdx;
   if (RequireIntervals)
     SlotIdx = LIS->getInstructionIndex(CurrPos).getRegSlot();
@@ -584,18 +577,13 @@ bool RegPressureTracker::recede(SmallVectorImpl<unsigned> *LiveUses,
         UntiedDefs.insert(Reg);
     }
   }
-  return true;
 }
 
 /// Advance across the current instruction.
-bool RegPressureTracker::advance() {
+void RegPressureTracker::advance() {
   assert(!TrackUntiedDefs && "unsupported mode");
 
-  // Check for the bottom of the analyzable region.
-  if (CurrPos == MBB->end()) {
-    closeRegion();
-    return false;
-  }
+  assert(CurrPos != MBB->end());
   if (!isTopClosed())
     closeTop();
 
@@ -653,7 +641,6 @@ bool RegPressureTracker::advance() {
   do
     ++CurrPos;
   while (CurrPos != MBB->end() && CurrPos->isDebugValue());
-  return true;
 }
 
 /// Find the max change in excess pressure across all sets.