[GlobalsAA] Restrict ModRef result if any internal method has its address taken.

Summary:
If there are any internal methods whose address was taken, conclude there is nothing known in relation of any other internal method and a global.

Reviewers: nlopes, sanjoy.google

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69690

diff --git a/llvm/include/llvm/Analysis/GlobalsModRef.h b/llvm/include/llvm/Analysis/GlobalsModRef.h
index 5d1c5a0..fa5b16c 100644 (file)
--- a/llvm/include/llvm/Analysis/GlobalsModRef.h
+++ b/llvm/include/llvm/Analysis/GlobalsModRef.h
@@ -39,6 +39,9 @@ class GlobalsAAResult : public AAResultBase<GlobalsAAResult> {
   /// The globals that do not have their addresses taken.
   SmallPtrSet<const GlobalValue *, 8> NonAddressTakenGlobals;
 
+  /// Are there functions with local linkage that may modify globals.
+  bool UnknownFunctionsWithLocalLinkage = false;
+
   /// IndirectGlobals - The memory pointed to by this global is known to be
   /// 'owned' by the global.
   SmallPtrSet<const GlobalValue *, 8> IndirectGlobals;

diff --git a/llvm/lib/Analysis/GlobalsModRef.cpp b/llvm/lib/Analysis/GlobalsModRef.cpp
index efdf970..758e827 100644 (file)
--- a/llvm/lib/Analysis/GlobalsModRef.cpp
+++ b/llvm/lib/Analysis/GlobalsModRef.cpp
@@ -286,7 +286,7 @@ GlobalsAAResult::getFunctionInfo(const Function *F) {
 void GlobalsAAResult::AnalyzeGlobals(Module &M) {
   SmallPtrSet<Function *, 32> TrackedFunctions;
   for (Function &F : M)
-    if (F.hasLocalLinkage())
+    if (F.hasLocalLinkage()) {
       if (!AnalyzeUsesOfPointer(&F)) {
         // Remember that we are tracking this global.
         NonAddressTakenGlobals.insert(&F);
@@ -294,7 +294,9 @@ void GlobalsAAResult::AnalyzeGlobals(Module &M) {
         Handles.emplace_front(*this, &F);
         Handles.front().I = Handles.begin();
         ++NumNonAddrTakenFunctions;
-      }
+      } else
+        UnknownFunctionsWithLocalLinkage = true;
+    }
 
   SmallPtrSet<Function *, 16> Readers, Writers;
   for (GlobalVariable &GV : M.globals())
@@ -526,9 +528,12 @@ void GlobalsAAResult::AnalyzeCallGraph(CallGraph &CG, Module &M) {
             FI.setMayReadAnyGlobal();
         } else {
           FI.addModRefInfo(ModRefInfo::ModRef);
-          // Can't say anything useful unless it's an intrinsic - they don't
-          // read or write global variables of the kind considered here.
-          KnowNothing = !F->isIntrinsic();
+          if (!F->onlyAccessesArgMemory())
+            FI.setMayReadAnyGlobal();
+          if (!F->isIntrinsic()) {
+            KnowNothing = true;
+            break;
+          }
         }
         continue;
       }
@@ -927,7 +932,9 @@ ModRefInfo GlobalsAAResult::getModRefInfo(const CallBase *Call,
   // global we are tracking, return information if we have it.
   if (const GlobalValue *GV =
           dyn_cast<GlobalValue>(GetUnderlyingObject(Loc.Ptr, DL)))
-    if (GV->hasLocalLinkage())
+    // If GV is internal to this IR and there is no function with local linkage
+    // that has had their address taken, keep looking for a tighter ModRefInfo.
+    if (GV->hasLocalLinkage() && !UnknownFunctionsWithLocalLinkage)
       if (const Function *F = Call->getCalledFunction())
         if (NonAddressTakenGlobals.count(GV))
           if (const FunctionInfo *FI = getFunctionInfo(F))

diff --git a/llvm/test/Analysis/GlobalsModRef/intrinsic_addressnottaken1.ll b/llvm/test/Analysis/GlobalsModRef/intrinsic_addressnottaken1.ll
new file mode 100644 (file)
index 0000000..934534b
--- /dev/null
+++ b/llvm/test/Analysis/GlobalsModRef/intrinsic_addressnottaken1.ll
@@ -0,0 +1,44 @@
+; RUN: opt -globals-aa -gvn -S < %s | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@deallocCalled = internal global i8 0, align 1
+
+; CHECK-LABEL: @main()
+define dso_local i32 @main() {
+entry:
+  %tmp0 = call i8* @llvm.objc.autoreleasePoolPush() #1
+  %tmp6 = load i8, i8* @deallocCalled, align 1
+  %tobool = icmp ne i8 %tmp6, 0
+  br i1 %tobool, label %if.else, label %if.end
+
+if.else:                                          ; preds = %entry
+  call void @__assert_fail() #0
+  unreachable
+
+; CHECK-LABEL: if.end:
+; CHECK-NEXT: call void @llvm.objc.autoreleasePoolPop
+; CHECK-NOT: load i8, i8* @deallocCalled
+if.end:                                           ; preds = %entry
+  call void @llvm.objc.autoreleasePoolPop(i8* %tmp0)
+  %tmp7 = load i8, i8* @deallocCalled, align 1
+  %tobool3 = icmp ne i8 %tmp7, 0
+  br i1 %tobool3, label %if.end6, label %if.else5
+
+if.else5:                                         ; preds = %if.end
+  call void @__assert_fail() #0
+  unreachable
+
+if.end6:                                          ; preds = %if.end
+  store i8 0, i8* @deallocCalled, align 1
+  ret i32 0
+}
+
+declare i8* @llvm.objc.autoreleasePoolPush() #1
+declare void @llvm.objc.autoreleasePoolPop(i8*) #1
+declare dso_local void @__assert_fail() #0
+
+attributes #0 = { noreturn nounwind }
+attributes #1 = { nounwind }
+

diff --git a/llvm/test/Analysis/GlobalsModRef/intrinsic_addressnottaken2.ll b/llvm/test/Analysis/GlobalsModRef/intrinsic_addressnottaken2.ll
new file mode 100644 (file)
index 0000000..d9874d7
--- /dev/null
+++ b/llvm/test/Analysis/GlobalsModRef/intrinsic_addressnottaken2.ll
@@ -0,0 +1,50 @@
+; RUN: opt -globals-aa -gvn -S < %s | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@deallocCalled = internal global i8 0, align 1
+
+define internal i8* @_i_Associated__dealloc() {
+entry:
+  store i8 1, i8* @deallocCalled, align 1
+  ret i8* null
+}
+
+; CHECK-LABEL: @main()
+define dso_local i32 @main() {
+entry:
+  %tmp0 = call i8* @llvm.objc.autoreleasePoolPush() #1
+  %tmp6 = load i8, i8* @deallocCalled, align 1
+  %tobool = icmp ne i8 %tmp6, 0
+  br i1 %tobool, label %if.else, label %if.end
+
+if.else:                                          ; preds = %entry
+  call void @__assert_fail() #0
+  unreachable
+
+; CHECK-LABEL: if.end:
+; CHECK-NEXT: call void @llvm.objc.autoreleasePoolPop
+; CHECK-NOT: load i8, i8* @deallocCalled
+if.end:                                           ; preds = %entry
+  call void @llvm.objc.autoreleasePoolPop(i8* %tmp0)
+  %tmp7 = load i8, i8* @deallocCalled, align 1
+  %tobool3 = icmp ne i8 %tmp7, 0
+  br i1 %tobool3, label %if.end6, label %if.else5
+
+if.else5:                                         ; preds = %if.end
+  call void @__assert_fail() #0
+  unreachable
+
+if.end6:                                          ; preds = %if.end
+  store i8 0, i8* @deallocCalled, align 1
+  ret i32 0
+}
+
+declare i8* @llvm.objc.autoreleasePoolPush() #1
+declare void @llvm.objc.autoreleasePoolPop(i8*) #1
+declare dso_local void @__assert_fail() #0
+
+attributes #0 = { noreturn nounwind }
+attributes #1 = { nounwind }
+

diff --git a/llvm/test/Analysis/GlobalsModRef/intrinsic_addresstaken.ll b/llvm/test/Analysis/GlobalsModRef/intrinsic_addresstaken.ll
new file mode 100644 (file)
index 0000000..18cf7c2
--- /dev/null
+++ b/llvm/test/Analysis/GlobalsModRef/intrinsic_addresstaken.ll
@@ -0,0 +1,53 @@
+; RUN: opt -globals-aa -gvn -S < %s | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@deallocCalled = internal global i8 0, align 1
+@.objc_method_list = internal global { i8* ()* } { i8* ()*  @_i_Associated__dealloc }, align 8
+@._OBJC_CLASS_Associated = global { i8* } { i8* bitcast ({ i8* ()* }* @.objc_method_list to i8*) }, align 8
+@._OBJC_INIT_CLASS_Associated = global { i8* }* @._OBJC_CLASS_Associated
+@llvm.used = appending global [1 x i8*] [i8* bitcast ({ i8* }** @._OBJC_INIT_CLASS_Associated to i8*)]
+
+define internal i8* @_i_Associated__dealloc() {
+entry:
+  store i8 1, i8* @deallocCalled, align 1
+  ret i8* null
+}
+
+; CHECK-LABEL: @main()
+define dso_local i32 @main() {
+entry:
+  %tmp0 = call i8* @llvm.objc.autoreleasePoolPush() #1
+  %tmp6 = load i8, i8* @deallocCalled, align 1
+  %tobool = icmp ne i8 %tmp6, 0
+  br i1 %tobool, label %if.else, label %if.end
+
+if.else:                                          ; preds = %entry
+  call void @__assert_fail() #0
+  unreachable
+
+; CHECK-LABEL: if.end:
+; CHECK-NEXT: call void @llvm.objc.autoreleasePoolPop
+; CHECK-NEXT: load i8, i8* @deallocCalled
+if.end:                                           ; preds = %entry
+  call void @llvm.objc.autoreleasePoolPop(i8* %tmp0)
+  %tmp7 = load i8, i8* @deallocCalled, align 1
+  %tobool3 = icmp ne i8 %tmp7, 0
+  br i1 %tobool3, label %if.end6, label %if.else5
+
+if.else5:                                         ; preds = %if.end
+  call void @__assert_fail() #0
+  unreachable
+
+if.end6:                                          ; preds = %if.end
+  store i8 0, i8* @deallocCalled, align 1
+  ret i32 0
+}
+
+declare i8* @llvm.objc.autoreleasePoolPush() #1
+declare void @llvm.objc.autoreleasePoolPop(i8*) #1
+declare dso_local void @__assert_fail() #0
+
+attributes #0 = { noreturn nounwind }
+attributes #1 = { nounwind }