Extract FindAvailablePtrLoadStore out of FindAvailableLoadedValue. NFCI

Summary:
Extract FindAvailablePtrLoadStore out of FindAvailableLoadedValue.
Prepare for upcoming change which will do phi-translation for load on
phi pointer in jump threading SimplifyPartiallyRedundantLoad.

This is in preparation for https://reviews.llvm.org/D30543

Reviewers: efriedma, sanjoy, davide, dberlin

Reviewed By: davide

Subscribers: junbuml, davide, llvm-commits

Differential Revision: https://reviews.llvm.org/D30524

llvm-svn: 298216

1 files changed, 18 insertions, 14 deletions

diff --git a/llvm/lib/Analysis/Loads.cpp b/llvm/lib/Analysis/Loads.cpp
index 5d842db912c..96799a459bf 100644
--- a/llvm/lib/Analysis/Loads.cpp
+++ b/llvm/lib/Analysis/Loads.cpp
@@ -312,22 +312,26 @@ Value *llvm::FindAvailableLoadedValue(LoadInst *Load,
                                       BasicBlock *ScanBB,
                                       BasicBlock::iterator &ScanFrom,
                                       unsigned MaxInstsToScan,
-                                      AliasAnalysis *AA, bool *IsLoadCSE,
+                                      AliasAnalysis *AA, bool *IsLoad,
                                       unsigned *NumScanedInst) {
-  if (MaxInstsToScan == 0)
-    MaxInstsToScan = ~0U;
-
-  Value *Ptr = Load->getPointerOperand();
-  Type *AccessTy = Load->getType();
-
-  // We can never remove a volatile load
-  if (Load->isVolatile())
-    return nullptr;
-
-  // Anything stronger than unordered is currently unimplemented.
+  // Don't CSE load that is volatile or anything stronger than unordered.
   if (!Load->isUnordered())
     return nullptr;
 
+  return FindAvailablePtrLoadStore(
+      Load->getPointerOperand(), Load->getType(), Load->isAtomic(), ScanBB,
+      ScanFrom, MaxInstsToScan, AA, IsLoad, NumScanedInst);
+}
+
+Value *llvm::FindAvailablePtrLoadStore(Value *Ptr, Type *AccessTy,
+                                       bool AtLeastAtomic, BasicBlock *ScanBB,
+                                       BasicBlock::iterator &ScanFrom,
+                                       unsigned MaxInstsToScan,
+                                       AliasAnalysis *AA, bool *IsLoadCSE,
+                                       unsigned *NumScanedInst) {
+  if (MaxInstsToScan == 0)
+    MaxInstsToScan = ~0U;
+
   const DataLayout &DL = ScanBB->getModule()->getDataLayout();
 
   // Try to get the store size for the type.
@@ -363,7 +367,7 @@ Value *llvm::FindAvailableLoadedValue(LoadInst *Load,
 
         // We can value forward from an atomic to a non-atomic, but not the
         // other way around.
-        if (LI->isAtomic() < Load->isAtomic())
+        if (LI->isAtomic() < AtLeastAtomic)
           return nullptr;
 
         if (IsLoadCSE)
@@ -382,7 +386,7 @@ Value *llvm::FindAvailableLoadedValue(LoadInst *Load,
 
         // We can value forward from an atomic to a non-atomic, but not the
         // other way around.
-        if (SI->isAtomic() < Load->isAtomic())
+        if (SI->isAtomic() < AtLeastAtomic)
           return nullptr;
 
         if (IsLoadCSE)