From 71183ed37cbc4af8f3e6e0e652116fc1266b662f Mon Sep 17 00:00:00 2001
From: Nadav Rotem <nrotem@apple.com>
Date: Wed, 12 Sep 2012 11:06:26 +0000
Subject: [PATCH] Add a flag to disable the code that looks for allocas which
 escaped the lifetime regions. This is useful for debugging. No testcase
 because without this check we fail on assertions when finding escaped
 allocas.

llvm-svn: 163702
---
 lib/CodeGen/StackColoring.cpp | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/lib/CodeGen/StackColoring.cpp b/lib/CodeGen/StackColoring.cpp
index 0deb35ad7fb..a14d730025f 100644
--- a/lib/CodeGen/StackColoring.cpp
+++ b/lib/CodeGen/StackColoring.cpp
@@ -59,12 +59,20 @@ using namespace llvm;
 
 static cl::opt<bool>
 DisableColoring("no-stack-coloring",
-               cl::init(false), cl::Hidden,
-               cl::desc("Suppress stack coloring"));
+        cl::init(false), cl::Hidden,
+        cl::desc("Disable stack coloring"));
 
-STATISTIC(NumMarkerSeen,  "Number of life markers found.");
+static cl::opt<bool>
+CheckEscapedAllocas("stack-coloring-check-escaped",
+        cl::init(true), cl::Hidden,
+        cl::desc("Look for allocas which escaped the lifetime region"));
+
+STATISTIC(NumMarkerSeen,  "Number of lifetime markers found.");
 STATISTIC(StackSpaceSaved, "Number of bytes saved due to merging slots.");
 STATISTIC(StackSlotMerged, "Number of stack slot merged.");
+STATISTIC(EscapedAllocas,
+          "Number of allocas that escaped the lifetime region");
+
 
 //===----------------------------------------------------------------------===//
 //                           StackColoring Pass
@@ -104,7 +112,7 @@ class StackColoring : public MachineFunctionPass {
   /// VNInfo is used for the construction of LiveIntervals.
   VNInfo::Allocator VNInfoAllocator;
   /// SlotIndex analysis object.
-  SlotIndexes* Indexes;
+  SlotIndexes *Indexes;
 
   /// The list of lifetime markers found. These markers are to be removed
   /// once the coloring is done.
@@ -533,7 +541,7 @@ void StackColoring::remapInstructions(DenseMap<int, int> &SlotRemap) {
 #ifndef NDEBUG
         if (!I->isDebugValue()) {
           SlotIndex Index = Indexes->getInstructionIndex(I);
-          LiveInterval* Interval = Intervals[FromSlot];
+          LiveInterval *Interval = Intervals[FromSlot];
           assert(Interval->find(Index) != Interval->end() &&
                "Found instruction usage outside of live range.");
         }
@@ -583,6 +591,7 @@ void StackColoring::removeInvalidSlotRanges() {
         if (Interval->find(Index) == Interval->end()) {
           Intervals[Slot]->clear();
           DEBUG(dbgs()<<"Invalidating range #"<<Slot<<"\n");
+          EscapedAllocas++;
         }
       }
     }
@@ -662,7 +671,10 @@ bool StackColoring::runOnMachineFunction(MachineFunction &Func) {
   // Propagate the liveness information.
   calculateLiveIntervals(NumSlots);
 
-  removeInvalidSlotRanges();
+  // Search for allocas which are used outside of the declared lifetime
+  // markers.
+  if (CheckEscapedAllocas)
+    removeInvalidSlotRanges();
 
   // Maps old slots to new slots.
   DenseMap<int, int> SlotRemap;