From 5494adac67038a74d1fac4969086e08e1a2b4d50 Mon Sep 17 00:00:00 2001
From: Eli Friedman <eli.friedman@gmail.com>
Date: Mon, 15 Aug 2011 20:54:19 +0000
Subject: Misc analysis passes that need to be aware of atomic load/store.

llvm-svn: 137650
---
 llvm/lib/Analysis/MemoryDependenceAnalysis.cpp | 36 +++++++++++++++++++-------
 1 file changed, 26 insertions(+), 10 deletions(-)

(limited to 'llvm/lib/Analysis/MemoryDependenceAnalysis.cpp')

diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index 34ba92509e5..cdff85a5134 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -120,21 +120,27 @@ AliasAnalysis::ModRefResult GetLocation(const Instruction *Inst,
                                         AliasAnalysis::Location &Loc,
                                         AliasAnalysis *AA) {
   if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
-    if (LI->isVolatile()) {
-      Loc = AliasAnalysis::Location();
+    if (LI->isUnordered()) {
+      Loc = AA->getLocation(LI);
+      return AliasAnalysis::Ref;
+    } else if (LI->getOrdering() == Monotonic) {
+      Loc = AA->getLocation(LI);
       return AliasAnalysis::ModRef;
     }
-    Loc = AA->getLocation(LI);
-    return AliasAnalysis::Ref;
+    Loc = AliasAnalysis::Location();
+    return AliasAnalysis::ModRef;
   }
 
   if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
-    if (SI->isVolatile()) {
-      Loc = AliasAnalysis::Location();
+    if (SI->isUnordered()) {
+      Loc = AA->getLocation(SI);
+      return AliasAnalysis::Mod;
+    } else if (SI->getOrdering() == Monotonic) {
+      Loc = AA->getLocation(SI);
       return AliasAnalysis::ModRef;
     }
-    Loc = AA->getLocation(SI);
-    return AliasAnalysis::Mod;
+    Loc = AliasAnalysis::Location();
+    return AliasAnalysis::ModRef;
   }
 
   if (const VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
@@ -270,8 +276,8 @@ unsigned MemoryDependenceAnalysis::
 getLoadLoadClobberFullWidthSize(const Value *MemLocBase, int64_t MemLocOffs,
                                 unsigned MemLocSize, const LoadInst *LI,
                                 const TargetData &TD) {
-  // We can only extend non-volatile integer loads.
-  if (!isa<IntegerType>(LI->getType()) || LI->isVolatile()) return 0;
+  // We can only extend simple integer loads.
+  if (!isa<IntegerType>(LI->getType()) || !LI->isSimple()) return 0;
   
   // Get the base of this load.
   int64_t LIOffs = 0;
@@ -369,6 +375,11 @@ getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad,
     // Values depend on loads if the pointers are must aliased.  This means that
     // a load depends on another must aliased load from the same value.
     if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+      // Atomic loads have complications involved.
+      // FIXME: This is overly conservative.
+      if (!LI->isUnordered())
+        return MemDepResult::getClobber(LI);
+
       AliasAnalysis::Location LoadLoc = AA->getLocation(LI);
       
       // If we found a pointer, check if it could be the same as our pointer.
@@ -424,6 +435,11 @@ getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad,
     }
     
     if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+      // Atomic stores have complications involved.
+      // FIXME: This is overly conservative.
+      if (!SI->isUnordered())
+        return MemDepResult::getClobber(SI);
+
       // If alias analysis can tell that this store is guaranteed to not modify
       // the query pointer, ignore it.  Use getModRefInfo to handle cases where
       // the query pointer points to constant memory etc.
-- 
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