Enhance alias analysis for atomic instructions a bit. Upgrade a couple alias-analysis tests to the new atomic instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140557 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/AliasAnalysis.h

@@ -136,6 +136,8 @@ public:
   Location getLocation(const LoadInst *LI);
   Location getLocation(const StoreInst *SI);
   Location getLocation(const VAArgInst *VI);
+  Location getLocation(const AtomicCmpXchgInst *CXI);
+  Location getLocation(const AtomicRMWInst *RMWI);
   static Location getLocationForSource(const MemTransferInst *MTI);
   static Location getLocationForDest(const MemIntrinsic *MI);
 
@@ -426,10 +428,7 @@ public:
 
   /// getModRefInfo (for cmpxchges) - Return whether information about whether
   /// a particular cmpxchg modifies or reads the specified memory location.
-  ModRefResult getModRefInfo(const AtomicCmpXchgInst *CX, const Location &Loc) {
-    // Conservatively correct.  (But there are obvious ways to be smarter.)
-    return ModRef;
-  }
+  ModRefResult getModRefInfo(const AtomicCmpXchgInst *CX, const Location &Loc);
 
   /// getModRefInfo (for cmpxchges) - A convenience wrapper.
   ModRefResult getModRefInfo(const AtomicCmpXchgInst *CX,
@@ -439,10 +438,7 @@ public:
 
   /// getModRefInfo (for atomicrmws) - Return whether information about whether
   /// a particular atomicrmw modifies or reads the specified memory location.
-  ModRefResult getModRefInfo(const AtomicRMWInst *RMW, const Location &Loc) {
-    // Conservatively correct.  (But there are obvious ways to be smarter.)
-    return ModRef;
-  }
+  ModRefResult getModRefInfo(const AtomicRMWInst *RMW, const Location &Loc);
 
   /// getModRefInfo (for atomicrmws) - A convenience wrapper.
   ModRefResult getModRefInfo(const AtomicRMWInst *RMW,

lib/Analysis/AliasAnalysis.cpp

@@ -237,6 +237,19 @@ AliasAnalysis::Location AliasAnalysis::getLocation(const VAArgInst *VI) {
                   VI->getMetadata(LLVMContext::MD_tbaa));
 }
 
+AliasAnalysis::Location
+AliasAnalysis::getLocation(const AtomicCmpXchgInst *CXI) {
+  return Location(CXI->getPointerOperand(),
+                  getTypeStoreSize(CXI->getCompareOperand()->getType()),
+                  CXI->getMetadata(LLVMContext::MD_tbaa));
+}
+
+AliasAnalysis::Location
+AliasAnalysis::getLocation(const AtomicRMWInst *RMWI) {
+  return Location(RMWI->getPointerOperand(),
+                  getTypeStoreSize(RMWI->getValOperand()->getType()),
+                  RMWI->getMetadata(LLVMContext::MD_tbaa));
+}
 
 AliasAnalysis::Location 
 AliasAnalysis::getLocationForSource(const MemTransferInst *MTI) {
@@ -317,6 +330,33 @@ AliasAnalysis::getModRefInfo(const VAArgInst *V, const Location &Loc) {
   return ModRef;
 }
 
+AliasAnalysis::ModRefResult
+AliasAnalysis::getModRefInfo(const AtomicCmpXchgInst *CX, const Location &Loc) {
+  // Acquire/Release cmpxchg has properties that matter for arbitrary addresses.
+  if (CX->getOrdering() > Monotonic)
+    return ModRef;
+
+  // If the cmpxchg address does not alias the location, it does not access it.
+  if (!alias(getLocation(CX), Loc))
+    return NoModRef;
+
+  return ModRef;
+}
+
+AliasAnalysis::ModRefResult
+AliasAnalysis::getModRefInfo(const AtomicRMWInst *RMW, const Location &Loc) {
+  // Acquire/Release atomicrmw has properties that matter for arbitrary addresses.
+  if (RMW->getOrdering() > Monotonic)
+    return ModRef;
+
+  // If the atomicrmw address does not alias the location, it does not access it.
+  if (!alias(getLocation(RMW), Loc))
+    return NoModRef;
+
+  return ModRef;
+}
+
+
 // AliasAnalysis destructor: DO NOT move this to the header file for
 // AliasAnalysis or else clients of the AliasAnalysis class may not depend on
 // the AliasAnalysis.o file in the current .a file, causing alias analysis

test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll

@@ -1,14 +1,12 @@
 ; RUN: opt -basicaa -gvn -instcombine -S < %s | FileCheck %s
 target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128"
 
-declare i8 @llvm.atomic.load.add.i8.p0i8(i8*, i8)
-
 define i8 @foo(i8* %ptr) {
   %P = getelementptr i8* %ptr, i32 0
   %Q = getelementptr i8* %ptr, i32 1
 ; CHECK: getelementptr
   %X = load i8* %P
-  %Y = call i8 @llvm.atomic.load.add.i8.p0i8(i8* %Q, i8 1)
+  %Y = atomicrmw add i8* %Q, i8 1 monotonic
   %Z = load i8* %P
 ; CHECK-NOT: = load
   %A = sub i8 %X, %Z

test/Analysis/BasicAA/cas.ll

@@ -6,10 +6,8 @@
 
 define i32 @main() {
   %a = load i32* @flag0
-  %b = tail call i32 @llvm.atomic.swap.i32.p0i32(i32* @turn, i32 1)
+  %b = atomicrmw xchg i32* @turn, i32 1 monotonic
   %c = load i32* @flag0
   %d = sub i32 %a, %c
   ret i32 %d
 }
-
-declare i32 @llvm.atomic.swap.i32.p0i32(i32*, i32) nounwind