[PATCH] MemoryDependenceAnalysis always depends on DominatorTree

[Matt Arsenault]

  Use unknown results in the case the dominator tree isn't available.

Hi nlewycky,

http://llvm-reviews.chandlerc.com/D583

CHANGE SINCE LAST DIFF
  http://llvm-reviews.chandlerc.com/D583?vs=1641&id=1660#toc

Files:
  lib/Analysis/MemoryDependenceAnalysis.cpp
  test/Analysis/MemoryDependenceAnalysis/lit.local.cfg
  test/Analysis/MemoryDependenceAnalysis/memdep_requires_dominator_tree.ll
  test/Transforms/GVN/unreachable_block_infinite_loop.ll

Index: lib/Analysis/MemoryDependenceAnalysis.cpp
===================================================================
--- lib/Analysis/MemoryDependenceAnalysis.cpp
+++ lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -913,7 +913,6 @@
                             SmallVectorImpl<NonLocalDepResult> &Result,
                             DenseMap<BasicBlock*, Value*> &Visited,
                             bool SkipFirstBlock) {
-
   // Look up the cached info for Pointer.
   ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad);
 
@@ -1001,8 +1000,17 @@
     for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
          I != E; ++I) {
       Visited.insert(std::make_pair(I->getBB(), Addr));
-      if (!I->getResult().isNonLocal() && DT->isReachableFromEntry(I->getBB()))
+      if (I->getResult().isNonLocal()) {
+        continue;
+      }
+
+      if (!DT) {
+        Result.push_back(NonLocalDepResult(I->getBB(),
+                                           MemDepResult::getUnknown(),
+                                           Addr));
+      } else if (DT->isReachableFromEntry(I->getBB())) {
         Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(), Addr));
+      }
     }
     ++NumCacheCompleteNonLocalPtr;
     return false;
@@ -1047,9 +1055,16 @@
                                                  NumSortedEntries);
 
       // If we got a Def or Clobber, add this to the list of results.
-      if (!Dep.isNonLocal() && DT->isReachableFromEntry(BB)) {
-        Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
-        continue;
+      if (!Dep.isNonLocal()) {
+        if (!DT) {
+          Result.push_back(NonLocalDepResult(BB,
+                                             MemDepResult::getUnknown(),
+                                             Pointer.getAddr()));
+          continue;
+        } else if (DT->isReachableFromEntry(BB)) {
+          Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
+          continue;
+        }
       }
     }
 
Index: test/Analysis/MemoryDependenceAnalysis/lit.local.cfg
===================================================================
--- /dev/null
+++ test/Analysis/MemoryDependenceAnalysis/lit.local.cfg
@@ -0,0 +1 @@
+config.suffixes = ['.ll']
Index: test/Analysis/MemoryDependenceAnalysis/memdep_requires_dominator_tree.ll
===================================================================
--- /dev/null
+++ test/Analysis/MemoryDependenceAnalysis/memdep_requires_dominator_tree.ll
@@ -0,0 +1,19 @@
+; RUN: opt -memdep -gvn < %s
+
+define void @__memdep_requires_dominator_tree(i32* nocapture %bufUInt, i32* nocapture %pattern) nounwind {
+entry:
+  br label %for.body
+
+for.exit:                                         ; preds = %for.body
+  ret void
+
+for.body:                                         ; preds = %for.body, %entry
+  %i.01 = phi i32 [ 0, %entry ], [ %tmp8.7, %for.body ]
+  %arrayidx = getelementptr i32* %bufUInt, i32 %i.01
+  %arrayidx5 = getelementptr i32* %pattern, i32 %i.01
+  %tmp6 = load i32* %arrayidx5, align 4
+  store i32 %tmp6, i32* %arrayidx, align 4
+  %tmp8.7 = add i32 %i.01, 8
+  %cmp.7 = icmp ult i32 %tmp8.7, 1024
+  br i1 %cmp.7, label %for.body, label %for.exit
+}
Index: test/Transforms/GVN/unreachable_block_infinite_loop.ll
===================================================================
--- /dev/null
+++ test/Transforms/GVN/unreachable_block_infinite_loop.ll
@@ -0,0 +1,14 @@
+; RUN: opt -memdep -gvn -disable-output
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-apple-darwin10.0"
+
+define i32 @test2() nounwind ssp {
+entry:
+    ret i32 0
+
+unreachable_block:
+    %a = add i32 %a, 1
+    ret i32 %a
+}
+
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