[cfe-commits] r153723 - in /cfe/trunk: lib/CodeGen/CGDecl.cpp lib/CodeGen/ItaniumCXXABI.cpp test/CodeGenCXX/static-init.cpp
John McCall
rjmccall at apple.com
Thu Mar 29 21:25:14 PDT 2012
Author: rjmccall
Date: Thu Mar 29 23:25:14 2012
New Revision: 153723
URL: http://llvm.org/viewvc/llvm-project?rev=153723&view=rev
Log:
When emitting a static local variable in C++, handle
the case that the variable already exists. Partly this is just
protection against people making crazy declarations with custom
asm labels or extern "C" names that intentionally collide with
the manglings of such variables, but the main reason is that we
can actually emit a static local variable twice with the
requirement that it match up. There may be other cases with
(e.g.) the various nested functions, but the main exemplar is
with constructor variants, where we can be forced into
double-emitting the function body under certain circumstances
like (currently) the presence of virtual bases.
Modified:
cfe/trunk/lib/CodeGen/CGDecl.cpp
cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
cfe/trunk/test/CodeGenCXX/static-init.cpp
Modified: cfe/trunk/lib/CodeGen/CGDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDecl.cpp?rev=153723&r1=153722&r2=153723&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDecl.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGDecl.cpp Thu Mar 29 23:25:14 2012
@@ -184,6 +184,24 @@
Name = GetStaticDeclName(*this, D, Separator);
llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
+
+ // In C++, there are strange possibilities here involving the
+ // double-emission of constructors and destructors.
+ if (CGM.getLangOpts().CPlusPlus) {
+ llvm::GlobalValue *value = CGM.getModule().getNamedValue(Name);
+ if (value && isa<llvm::GlobalVariable>(value) &&
+ value->getType() ==
+ LTy->getPointerTo(CGM.getContext().getTargetAddressSpace(Ty)))
+ return cast<llvm::GlobalVariable>(value);
+
+ if (value) {
+ CGM.Error(D.getLocation(),
+ "problem emitting static variable: already present as "
+ "different kind of symbol");
+ // Fall through and implicitly give it a uniqued name.
+ }
+ }
+
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(CGM.getModule(), LTy,
Ty.isConstant(getContext()), Linkage,
Modified: cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp?rev=153723&r1=153722&r2=153723&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp (original)
+++ cfe/trunk/lib/CodeGen/ItaniumCXXABI.cpp Thu Mar 29 23:25:14 2012
@@ -1051,7 +1051,7 @@
namespace {
struct CallGuardAbort : EHScopeStack::Cleanup {
llvm::GlobalVariable *Guard;
- CallGuardAbort(llvm::GlobalVariable *Guard) : Guard(Guard) {}
+ CallGuardAbort(llvm::GlobalVariable *guard) : Guard(guard) {}
void Emit(CodeGenFunction &CGF, Flags flags) {
CGF.Builder.CreateCall(getGuardAbortFn(CGF.CGM, Guard->getType()), Guard)
@@ -1073,35 +1073,54 @@
bool threadsafe =
(getContext().getLangOpts().ThreadsafeStatics && D.isLocalVarDecl());
- llvm::IntegerType *GuardTy;
+ llvm::IntegerType *guardTy;
// If we have a global variable with internal linkage and thread-safe statics
// are disabled, we can just let the guard variable be of type i8.
bool useInt8GuardVariable = !threadsafe && GV->hasInternalLinkage();
if (useInt8GuardVariable) {
- GuardTy = CGF.Int8Ty;
+ guardTy = CGF.Int8Ty;
} else {
// Guard variables are 64 bits in the generic ABI and 32 bits on ARM.
- GuardTy = (IsARM ? CGF.Int32Ty : CGF.Int64Ty);
+ guardTy = (IsARM ? CGF.Int32Ty : CGF.Int64Ty);
}
- llvm::PointerType *GuardPtrTy = GuardTy->getPointerTo();
+ llvm::PointerType *guardPtrTy = guardTy->getPointerTo();
// Create the guard variable.
- SmallString<256> GuardVName;
- llvm::raw_svector_ostream Out(GuardVName);
- getMangleContext().mangleItaniumGuardVariable(&D, Out);
- Out.flush();
-
- // Just absorb linkage and visibility from the variable.
- llvm::GlobalVariable *GuardVariable =
- new llvm::GlobalVariable(CGM.getModule(), GuardTy,
- false, GV->getLinkage(),
- llvm::ConstantInt::get(GuardTy, 0),
- GuardVName.str());
- GuardVariable->setVisibility(GV->getVisibility());
+ SmallString<256> guardName;
+ {
+ llvm::raw_svector_ostream out(guardName);
+ getMangleContext().mangleItaniumGuardVariable(&D, out);
+ out.flush();
+ }
+
+ // There are strange possibilities here involving the
+ // double-emission of constructors and destructors.
+ llvm::GlobalVariable *guard = nullptr;
+ if (llvm::GlobalValue *existingGuard
+ = CGM.getModule().getNamedValue(guardName.str())) {
+ if (isa<llvm::GlobalVariable>(existingGuard) &&
+ existingGuard->getType() == guardPtrTy) {
+ guard = cast<llvm::GlobalVariable>(existingGuard); // okay
+ } else {
+ CGM.Error(D.getLocation(),
+ "problem emitting guard for static variable: "
+ "already present as different kind of symbol");
+ // Fall through and implicitly give it a uniqued name.
+ }
+ }
+ if (!guard) {
+ // Just absorb linkage and visibility from the variable.
+ guard = new llvm::GlobalVariable(CGM.getModule(), guardTy,
+ false, GV->getLinkage(),
+ llvm::ConstantInt::get(guardTy, 0),
+ guardName.str());
+ guard->setVisibility(GV->getVisibility());
+ }
+
// Test whether the variable has completed initialization.
- llvm::Value *IsInitialized;
+ llvm::Value *isInitialized;
// ARM C++ ABI 3.2.3.1:
// To support the potential use of initialization guard variables
@@ -1115,9 +1134,9 @@
// ...
// }
if (IsARM && !useInt8GuardVariable) {
- llvm::Value *V = Builder.CreateLoad(GuardVariable);
+ llvm::Value *V = Builder.CreateLoad(guard);
V = Builder.CreateAnd(V, Builder.getInt32(1));
- IsInitialized = Builder.CreateIsNull(V, "guard.uninitialized");
+ isInitialized = Builder.CreateIsNull(V, "guard.uninitialized");
// Itanium C++ ABI 3.3.2:
// The following is pseudo-code showing how these functions can be used:
@@ -1135,10 +1154,9 @@
// }
} else {
// Load the first byte of the guard variable.
- llvm::Type *PtrTy = Builder.getInt8PtrTy();
- llvm::LoadInst *LI =
- Builder.CreateLoad(Builder.CreateBitCast(GuardVariable, PtrTy));
- LI->setAlignment(1);
+ llvm::LoadInst *load =
+ Builder.CreateLoad(Builder.CreateBitCast(guard, CGM.Int8PtrTy));
+ load->setAlignment(1);
// Itanium ABI:
// An implementation supporting thread-safety on multiprocessor
@@ -1147,16 +1165,16 @@
//
// In LLVM, we do this by marking the load Acquire.
if (threadsafe)
- LI->setAtomic(llvm::Acquire);
+ load->setAtomic(llvm::Acquire);
- IsInitialized = Builder.CreateIsNull(LI, "guard.uninitialized");
+ isInitialized = Builder.CreateIsNull(load, "guard.uninitialized");
}
llvm::BasicBlock *InitCheckBlock = CGF.createBasicBlock("init.check");
llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end");
// Check if the first byte of the guard variable is zero.
- Builder.CreateCondBr(IsInitialized, InitCheckBlock, EndBlock);
+ Builder.CreateCondBr(isInitialized, InitCheckBlock, EndBlock);
CGF.EmitBlock(InitCheckBlock);
@@ -1164,7 +1182,7 @@
if (threadsafe) {
// Call __cxa_guard_acquire.
llvm::Value *V
- = Builder.CreateCall(getGuardAcquireFn(CGM, GuardPtrTy), GuardVariable);
+ = Builder.CreateCall(getGuardAcquireFn(CGM, guardPtrTy), guard);
llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init");
@@ -1172,7 +1190,7 @@
InitBlock, EndBlock);
// Call __cxa_guard_abort along the exceptional edge.
- CGF.EHStack.pushCleanup<CallGuardAbort>(EHCleanup, GuardVariable);
+ CGF.EHStack.pushCleanup<CallGuardAbort>(EHCleanup, guard);
CGF.EmitBlock(InitBlock);
}
@@ -1185,9 +1203,9 @@
CGF.PopCleanupBlock();
// Call __cxa_guard_release. This cannot throw.
- Builder.CreateCall(getGuardReleaseFn(CGM, GuardPtrTy), GuardVariable);
+ Builder.CreateCall(getGuardReleaseFn(CGM, guardPtrTy), guard);
} else {
- Builder.CreateStore(llvm::ConstantInt::get(GuardTy, 1), GuardVariable);
+ Builder.CreateStore(llvm::ConstantInt::get(guardTy, 1), guard);
}
CGF.EmitBlock(EndBlock);
Modified: cfe/trunk/test/CodeGenCXX/static-init.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/static-init.cpp?rev=153723&r1=153722&r2=153723&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/static-init.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/static-init.cpp Thu Mar 29 23:25:14 2012
@@ -79,3 +79,53 @@
c::main();
}
}
+
+// rdar://problem/11091093
+// Static variables should be consistent across constructor
+// or destructor variants.
+namespace test2 {
+ struct A {
+ A();
+ ~A();
+ };
+
+ struct B : virtual A {
+ B();
+ ~B();
+ };
+
+ // If we ever implement this as a delegate ctor call, just change
+ // this to take variadic arguments or something.
+ extern int foo();
+ B::B() {
+ static int x = foo();
+ }
+ // CHECK: define void @_ZN5test21BC1Ev
+ // CHECK: load atomic i8* bitcast (i64* @_ZGVZN5test21BC1EvE1x to i8*) acquire,
+ // CHECK: call i32 @__cxa_guard_acquire(i64* @_ZGVZN5test21BC1EvE1x)
+ // CHECK: [[T0:%.*]] = call i32 @_ZN5test23fooEv()
+ // CHECK: store i32 [[T0]], i32* @_ZZN5test21BC1EvE1x,
+ // CHECK: call void @__cxa_guard_release(i64* @_ZGVZN5test21BC1EvE1x)
+
+ // CHECK: define void @_ZN5test21BC2Ev
+ // CHECK: load atomic i8* bitcast (i64* @_ZGVZN5test21BC1EvE1x to i8*) acquire,
+ // CHECK: call i32 @__cxa_guard_acquire(i64* @_ZGVZN5test21BC1EvE1x)
+ // CHECK: [[T0:%.*]] = call i32 @_ZN5test23fooEv()
+ // CHECK: store i32 [[T0]], i32* @_ZZN5test21BC1EvE1x,
+ // CHECK: call void @__cxa_guard_release(i64* @_ZGVZN5test21BC1EvE1x)
+
+ // This is just for completeness, because we actually emit this
+ // using a delegate dtor call.
+ B::~B() {
+ static int y = foo();
+ }
+ // CHECK: define void @_ZN5test21BD1Ev(
+ // CHECK: call void @_ZN5test21BD2Ev(
+
+ // CHECK: define void @_ZN5test21BD2Ev(
+ // CHECK: load atomic i8* bitcast (i64* @_ZGVZN5test21BD1EvE1y to i8*) acquire,
+ // CHECK: call i32 @__cxa_guard_acquire(i64* @_ZGVZN5test21BD1EvE1y)
+ // CHECK: [[T0:%.*]] = call i32 @_ZN5test23fooEv()
+ // CHECK: store i32 [[T0]], i32* @_ZZN5test21BD1EvE1y,
+ // CHECK: call void @__cxa_guard_release(i64* @_ZGVZN5test21BD1EvE1y)
+}
More information about the cfe-commits
mailing list