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authorReid Kleckner <reid@kleckner.net>2013-04-30 20:15:14 +0000
committerReid Kleckner <reid@kleckner.net>2013-04-30 20:15:14 +0000
commit3d2f000df9311bfccb6d2ac350be3d3efa5a412b (patch)
tree5a1b96031f88223113f0d68cbffb1602ed178fdd /lib/CodeGen
parentc7d77b25a37acad689ae5c318fdf80fde92983f0 (diff)
[ms-cxxabi] Implement member pointer comparisons
Summary: Like Itanium, comparisons are basically bitwise comparisons of the two values, with an exception for null member function pointers. If two function pointers are null, only the function pointer field matters for comparison purposes. The rest of the bits can be arbitrary. We take advantage of this in isZeroInitializable(), and it may matter once we start emitting conversions. Reviewers: rjmccall CC: cfe-commits Differential Revision: http://llvm-reviews.chandlerc.com/D695 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180800 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen')
-rw-r--r--lib/CodeGen/MicrosoftCXXABI.cpp72
1 files changed, 72 insertions, 0 deletions
diff --git a/lib/CodeGen/MicrosoftCXXABI.cpp b/lib/CodeGen/MicrosoftCXXABI.cpp
index 92bc538f20..d22a5e9072 100644
--- a/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -149,6 +149,12 @@ public:
virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
CharUnits offset);
+ virtual llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF,
+ llvm::Value *L,
+ llvm::Value *R,
+ const MemberPointerType *MPT,
+ bool Inequality);
+
virtual llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *MemPtr,
const MemberPointerType *MPT);
@@ -415,6 +421,10 @@ static bool hasVBPtrOffsetField(MSInheritanceModel Inheritance) {
return Inheritance == MSIM_Unspecified;
}
+static bool hasOnlyOneField(MSInheritanceModel Inheritance) {
+ return Inheritance <= MSIM_SinglePolymorphic;
+}
+
// Only member pointers to functions need a this adjustment, since it can be
// combined with the field offset for data pointers.
static bool hasNonVirtualBaseAdjustmentField(const MemberPointerType *MPT,
@@ -531,6 +541,68 @@ MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT,
return llvm::ConstantStruct::getAnon(fields);
}
+/// Member pointers are the same if they're either bitwise identical *or* both
+/// null. Null-ness for function members is determined by the first field,
+/// while for data member pointers we must compare all fields.
+llvm::Value *
+MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF,
+ llvm::Value *L,
+ llvm::Value *R,
+ const MemberPointerType *MPT,
+ bool Inequality) {
+ CGBuilderTy &Builder = CGF.Builder;
+
+ // Handle != comparisons by switching the sense of all boolean operations.
+ llvm::ICmpInst::Predicate Eq;
+ llvm::Instruction::BinaryOps And, Or;
+ if (Inequality) {
+ Eq = llvm::ICmpInst::ICMP_NE;
+ And = llvm::Instruction::Or;
+ Or = llvm::Instruction::And;
+ } else {
+ Eq = llvm::ICmpInst::ICMP_EQ;
+ And = llvm::Instruction::And;
+ Or = llvm::Instruction::Or;
+ }
+
+ // If this is a single field member pointer (single inheritance), this is a
+ // single icmp.
+ const CXXRecordDecl *RD = MPT->getClass()->getAsCXXRecordDecl();
+ MSInheritanceModel Inheritance = RD->getMSInheritanceModel();
+ if (hasOnlyOneField(Inheritance))
+ return Builder.CreateICmp(Eq, L, R);
+
+ // Compare the first field.
+ llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0");
+ llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0");
+ llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first");
+
+ // Compare everything other than the first field.
+ llvm::Value *Res = 0;
+ llvm::StructType *LType = cast<llvm::StructType>(L->getType());
+ for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) {
+ llvm::Value *LF = Builder.CreateExtractValue(L, I);
+ llvm::Value *RF = Builder.CreateExtractValue(R, I);
+ llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest");
+ if (Res)
+ Res = Builder.CreateBinOp(And, Res, Cmp);
+ else
+ Res = Cmp;
+ }
+
+ // Check if the first field is 0 if this is a function pointer.
+ if (MPT->isMemberFunctionPointer()) {
+ // (l1 == r1 && ...) || l0 == 0
+ llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType());
+ llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero");
+ Res = Builder.CreateBinOp(Or, Res, IsZero);
+ }
+
+ // Combine the comparison of the first field, which must always be true for
+ // this comparison to succeeed.
+ return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp");
+}
+
llvm::Value *
MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
llvm::Value *MemPtr,