Create an equivalence class of global variables that DSA will never be able

to tell apart anyway, and only track the leader for of these equivalence
classes in our graphs.

This dramatically reduces the number of GlobalValue*'s that appear in scalar
maps, which A) reduces memory usage, by eliminating many many scalarmap entries
and B) reduces time for operations that need to execute an operation for each
global in the scalar map.

As an example, this reduces the memory used to analyze 176.gcc from 1GB to
511MB, which (while it's still way too much) is better because it doesn't hit
swap anymore.  On eon, this shrinks the local graphs from 14MB to 6.8MB,
shrinks the bu+td graphs of povray from 50M to 40M, shrinks the TD graphs of
130.li from 8.8M to 3.6M, etc.

This change also speeds up DSA on large programs where this makes a big
difference.  For example, 130.li goes from 1.17s -> 0.56s, 134.perl goes
from 2.14 -> 0.93s, povray goes from 15.63s->7.99s (!!!).

This also apparently either fixes the problem that caused DSA to crash on
perlbmk and gcc, or it hides it, because DSA now works on these.  These
both take entirely too much time in the TD pass (147s for perl, 538s for
gcc, vs 7.67/5.9s in the bu pass for either one), but this is a known
problem that I'll deal with later.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20696 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 3 deletions

diff --git a/lib/Analysis/DataStructure/TopDownClosure.cpp b/lib/Analysis/DataStructure/TopDownClosure.cpp
index 580f22884f..9a661e24a5 100644
--- a/lib/Analysis/DataStructure/TopDownClosure.cpp
+++ b/lib/Analysis/DataStructure/TopDownClosure.cpp
@@ -53,7 +53,8 @@ void TDDataStructures::markReachableFunctionsExternallyAccessible(DSNode *N,
 //
 bool TDDataStructures::runOnModule(Module &M) {
   BUDataStructures &BU = getAnalysis<BUDataStructures>();
-  GlobalsGraph = new DSGraph(BU.getGlobalsGraph());
+  GlobalECs = BU.getGlobalECs();
+  GlobalsGraph = new DSGraph(BU.getGlobalsGraph(), GlobalECs);
   GlobalsGraph->setPrintAuxCalls();
 
   // Figure out which functions must not mark their arguments complete because
@@ -115,7 +116,7 @@ bool TDDataStructures::runOnModule(Module &M) {
 DSGraph &TDDataStructures::getOrCreateDSGraph(Function &F) {
   DSGraph *&G = DSInfo[&F];
   if (G == 0) { // Not created yet?  Clone BU graph...
-    G = new DSGraph(getAnalysis<BUDataStructures>().getDSGraph(F));
+    G = new DSGraph(getAnalysis<BUDataStructures>().getDSGraph(F), GlobalECs);
     G->getAuxFunctionCalls().clear();
     G->setPrintAuxCalls();
     G->setGlobalsGraph(GlobalsGraph);
@@ -324,7 +325,7 @@ void TDDataStructures::copyValue(Value *From, Value *To) {
   if (Function *FromF = dyn_cast<Function>(From)) {
     Function *ToF = cast<Function>(To);
     assert(!DSInfo.count(ToF) && "New Function already exists!");
-    DSGraph *NG = new DSGraph(getDSGraph(*FromF));
+    DSGraph *NG = new DSGraph(getDSGraph(*FromF), GlobalECs);
     DSInfo[ToF] = NG;
     assert(NG->getReturnNodes().size() == 1 && "Cannot copy SCC's yet!");