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[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
This commit is contained in:
Alina Sbirlea 2019-10-31 12:35:46 -07:00
parent a247bd1f27
commit db69f1b229
5 changed files with 163 additions and 6 deletions
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3
llvm/include/llvm/Analysis/GlobalsModRef.h
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@ -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;

19
llvm/lib/Analysis/GlobalsModRef.cpp
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@ -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))

44
llvm/test/Analysis/GlobalsModRef/intrinsic_addressnottaken1.ll Normal file
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@ -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 }

50
llvm/test/Analysis/GlobalsModRef/intrinsic_addressnottaken2.ll Normal file
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@ -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 }

53
llvm/test/Analysis/GlobalsModRef/intrinsic_addresstaken.ll Normal file
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@ -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 }