[llvm-commits] [llvm] r91787 - in /llvm/trunk: lib/Analysis/MemoryDependenceAnalysis.cpp test/Transforms/GVN/rle-phi-translate.ll

[Chris Lattner]

Author: lattner
Date: Sat Dec 19 15:29:22 2009
New Revision: 91787

URL: http://llvm.org/viewvc/llvm-project?rev=91787&view=rev
Log:
fix an overly conservative caching issue that caused memdep to
cache a pointer as being unavailable due to phi trans in the
wrong place.  This would cause later queries to fail even when
they didn't involve phi trans.

Modified:
    llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp
    llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll

Modified: llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp?rev=91787&r1=91786&r2=91787&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/MemoryDependenceAnalysis.cpp Sat Dec 19 15:29:22 2009
@@ -894,36 +894,12 @@
                                PredPtrVal);
         Result.push_back(Entry);
 
-        // Add it to the cache for this CacheKey so that subsequent queries get
-        // this result.
-        Cache = &NonLocalPointerDeps[CacheKey].second;
-        MemoryDependenceAnalysis::NonLocalDepInfo::iterator It =
-          std::upper_bound(Cache->begin(), Cache->end(), Entry);
-        
-        if (It != Cache->begin() && (It-1)->getBB() == Pred)
-          --It;
-
-        if (It == Cache->end() || It->getBB() != Pred) {
-          Cache->insert(It, Entry);
-          // Add it to the reverse map.
-          ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey);
-        } else if (!It->getResult().isDirty()) {
-          // noop
-        } else if (It->getResult().getInst() == Pred->getTerminator()) {
-          // Same instruction, clear the dirty marker.
-          It->setResult(Entry.getResult(), PredPtrVal);
-        } else if (It->getResult().getInst() == 0) {
-          // Dirty, with no instruction, just add this.
-          It->setResult(Entry.getResult(), PredPtrVal);
-          ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey);
-        } else {
-          // Otherwise, dirty with a different instruction.
-          RemoveFromReverseMap(ReverseNonLocalPtrDeps,
-                               It->getResult().getInst(), CacheKey);
-          It->setResult(Entry.getResult(),PredPtrVal);
-          ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey);
-        }
-        Cache = 0;
+        // Since we had a phi translation failure, the cache for CacheKey won't
+        // include all of the entries that we need to immediately satisfy future
+        // queries.  Mark this in NonLocalPointerDeps by setting the
+        // BBSkipFirstBlockPair pointer to null.  This requires reuse of the
+        // cached value to do more work but not miss the phi trans failure.
+        NonLocalPointerDeps[CacheKey].first = BBSkipFirstBlockPair();
         continue;
       }
 
@@ -961,10 +937,10 @@
       NumSortedEntries = Cache->size();
     }
     
-    // Since we did phi translation, the "Cache" set won't contain all of the
+    // Since we failed phi translation, the "Cache" set won't contain all of the
     // results for the query.  This is ok (we can still use it to accelerate
     // specific block queries) but we can't do the fastpath "return all
-    // results from the set"  Clear out the indicator for this.
+    // results from the set".  Clear out the indicator for this.
     CacheInfo->first = BBSkipFirstBlockPair();
     
     // If *nothing* works, mark the pointer as being clobbered by the first

Modified: llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll?rev=91787&r1=91786&r2=91787&view=diff

==============================================================================
--- llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll (original)
+++ llvm/trunk/test/Transforms/GVN/rle-phi-translate.ll Sat Dec 19 15:29:22 2009
@@ -112,3 +112,35 @@
   ret i32 %dv
 }
 
+
+
+; void test5(int N, double* G) {
+;   for (long j = 1; j < 1000; j++)
+;     G[j] = G[j] + G[j-1];
+; }
+;
+; Should compile into one load in the loop.
+define void @test5(i32 %N, double* nocapture %G) nounwind ssp {
+; CHECK: @test5
+bb.nph:
+  br label %for.body
+
+for.body:
+  %indvar = phi i64 [ 0, %bb.nph ], [ %tmp, %for.body ]
+  %arrayidx6 = getelementptr double* %G, i64 %indvar
+  %tmp = add i64 %indvar, 1
+  %arrayidx = getelementptr double* %G, i64 %tmp
+  %tmp3 = load double* %arrayidx
+  %tmp7 = load double* %arrayidx6
+  %add = fadd double %tmp3, %tmp7
+  store double %add, double* %arrayidx
+  %exitcond = icmp eq i64 %tmp, 999
+  br i1 %exitcond, label %for.end, label %for.body
+; CHECK: for.body:
+; CHECK: phi double
+; CHECK: load double
+; CHECK-NOT: load double
+; CHECK: br i1
+for.end:
+  ret void
+}