!fixup check underlying obj

Author: fhahn

llvm/lib/Transforms/Utils/GlobalStatus.cpp

@@ -8,6 +8,7 @@
 
 #include "llvm/Transforms/Utils/GlobalStatus.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/Constants.h"
@@ -17,6 +18,7 @@
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/PatternMatch.h"
 #include "llvm/IR/Use.h"
 #include "llvm/IR/User.h"
 #include "llvm/IR/Value.h"
@@ -26,6 +28,7 @@
 #include <cassert>
 
 using namespace llvm;
+using namespace llvm::PatternMatch;
 
 /// Return the stronger of the two ordering. If the two orderings are acquire
 /// and release, then return AcquireRelease.
@@ -61,45 +64,6 @@ bool llvm::isSafeToDestroyConstant(const Constant *C) {
   return true;
 }
 
-static bool
-maybePointerToDifferentObjectRecursive(Value *V,
-                                       SmallPtrSetImpl<Value *> &Visited) {
-  if (!Visited.insert(V).second)
-    return false;
-
-  if (Visited.size() > 32)
-    return true;
-
-  // PtrToInt may be used to construct a pointer to a different object. Loads
-  // and calls may return a pointer for a different object.
-  if (isa<PtrToIntInst, LoadInst, CallInst>(V))
-    return true;
-
-  if (auto *CE = dyn_cast<ConstantExpr>(V)) {
-    if (CE->getOpcode() == Instruction::PtrToInt)
-      return true;
-
-    for (auto &Op : CE->operands()) {
-      if (maybePointerToDifferentObjectRecursive(Op.get(), Visited))
-        return true;
-    }
-    return false;
-  }
-
-  if (auto *U = dyn_cast<User>(V)) {
-    for (auto &Op : U->operands()) {
-      if (maybePointerToDifferentObjectRecursive(Op.get(), Visited))
-        return true;
-    }
-  }
-  return false;
-}
-
-bool maybePointerToDifferentObject(Value *V) {
-  SmallPtrSet<Value *, 32> Visited;
-  return maybePointerToDifferentObjectRecursive(V, Visited);
-}
-
 static bool analyzeGlobalAux(const Value *V, GlobalStatus &GS,
                              SmallPtrSetImpl<const Value *> &VisitedUsers) {
   if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
@@ -198,10 +162,15 @@ static bool analyzeGlobalAux(const Value *V, GlobalStatus &GS,
       } else if (isa<CmpInst>(I)) {
         GS.IsCompared = true;
 
-        if (VisitedUsers.insert(I).second) {
-          for (Value *Op : I->operands())
-            if (Op != V && maybePointerToDifferentObject(Op))
-              return true;
+        const Value *UO = nullptr;
+        for (Value *Op : I->operands()) {
+          if (match(Op, m_Zero()))
+            continue;
+          const Value *OpUO = getUnderlyingObject(Op);
+          if (!UO)
+            UO = OpUO;
+          if (!OpUO || UO != OpUO)
+            return true;
         }
       } else if (const MemTransferInst *MTI = dyn_cast<MemTransferInst>(I)) {
         if (MTI->isVolatile())

llvm/test/Transforms/GlobalOpt/globals-compares-with-ptrtoint.ll

@@ -21,6 +21,8 @@
 ; CHECK: @C = internal global i64 0
 ; CHECK: @D = internal global i64 0
 ; CHECK: @G = internal global i64 0
+; CHECK: @H = internal global i64 0
+; CHECK: @J = internal global [2 x ptr] zeroinitializer
 ;.
 define i64 @A_and_B_cmp_ptrtoint_constant_expr() {
 ; CHECK-LABEL: define i64 @A_and_B_cmp_ptrtoint_constant_expr() local_unnamed_addr {
@@ -153,7 +155,8 @@ define ptr @compare_arg(ptr %a) {
 ; CHECK-NEXT:    [[C:%.*]] = icmp eq ptr [[A]], @J
 ; CHECK-NEXT:    br i1 [[C]], label %[[THEN:.*]], label %[[ELSE:.*]]
 ; CHECK:       [[THEN]]:
-; CHECK-NEXT:    ret ptr null
+; CHECK-NEXT:    [[L:%.*]] = load ptr, ptr @J, align 8
+; CHECK-NEXT:    ret ptr [[L]]
 ; CHECK:       [[ELSE]]:
 ; CHECK-NEXT:    ret ptr null
 ;