[clang][bytecode] Fix unsigned wraparound behavior with bitfields #164445
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@llvm/pr-subscribers-clang Author: Timm Baeder (tbaederr) Changesand inc/dec operations. We need to truncate the new value to the bitfield bitwidth. Full diff: https://github.com/llvm/llvm-project/pull/164445.diff 5 Files Affected:
diff --git a/clang/lib/AST/ByteCode/Compiler.cpp b/clang/lib/AST/ByteCode/Compiler.cpp
index f7731f06b664c..53e3c184ad081 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -6438,6 +6438,13 @@ bool Compiler<Emitter>::visitFunc(const FunctionDecl *F) {
return this->emitNoRet(SourceInfo{});
}
+static uint32_t getBitWidth(const Expr *E) {
+ assert(E->refersToBitField());
+ const auto *ME = cast<MemberExpr>(E);
+ const auto *FD = cast<FieldDecl>(ME->getMemberDecl());
+ return FD->getBitWidthValue();
+}
+
template <class Emitter>
bool Compiler<Emitter>::VisitUnaryOperator(const UnaryOperator *E) {
const Expr *SubExpr = E->getSubExpr();
@@ -6466,10 +6473,15 @@ bool Compiler<Emitter>::VisitUnaryOperator(const UnaryOperator *E) {
return DiscardResult ? this->emitPopPtr(E) : true;
}
- if (T == PT_Float) {
+ if (T == PT_Float)
return DiscardResult ? this->emitIncfPop(getFPOptions(E), E)
: this->emitIncf(getFPOptions(E), E);
- }
+
+ if (SubExpr->refersToBitField())
+ return DiscardResult ? this->emitIncPopBitfield(*T, E->canOverflow(),
+ getBitWidth(SubExpr), E)
+ : this->emitIncBitfield(*T, E->canOverflow(),
+ getBitWidth(SubExpr), E);
return DiscardResult ? this->emitIncPop(*T, E->canOverflow(), E)
: this->emitInc(*T, E->canOverflow(), E);
@@ -6490,9 +6502,15 @@ bool Compiler<Emitter>::VisitUnaryOperator(const UnaryOperator *E) {
return DiscardResult ? this->emitPopPtr(E) : true;
}
- if (T == PT_Float) {
+ if (T == PT_Float)
return DiscardResult ? this->emitDecfPop(getFPOptions(E), E)
: this->emitDecf(getFPOptions(E), E);
+
+ if (SubExpr->refersToBitField()) {
+ return DiscardResult ? this->emitDecPopBitfield(*T, E->canOverflow(),
+ getBitWidth(SubExpr), E)
+ : this->emitDecBitfield(*T, E->canOverflow(),
+ getBitWidth(SubExpr), E);
}
return DiscardResult ? this->emitDecPop(*T, E->canOverflow(), E)
@@ -6521,6 +6539,11 @@ bool Compiler<Emitter>::VisitUnaryOperator(const UnaryOperator *E) {
if (DiscardResult) {
if (T == PT_Float)
return this->emitIncfPop(getFPOptions(E), E);
+ if (SubExpr->refersToBitField())
+ return DiscardResult ? this->emitIncPopBitfield(*T, E->canOverflow(),
+ getBitWidth(SubExpr), E)
+ : this->emitIncBitfield(*T, E->canOverflow(),
+ getBitWidth(SubExpr), E);
return this->emitIncPop(*T, E->canOverflow(), E);
}
@@ -6536,6 +6559,11 @@ bool Compiler<Emitter>::VisitUnaryOperator(const UnaryOperator *E) {
return false;
if (!this->emitStoreFloat(E))
return false;
+ } else if (SubExpr->refersToBitField()) {
+ assert(isIntegralType(*T));
+ if (!this->emitPreIncBitfield(*T, E->canOverflow(), getBitWidth(SubExpr),
+ E))
+ return false;
} else {
assert(isIntegralType(*T));
if (!this->emitPreInc(*T, E->canOverflow(), E))
@@ -6566,6 +6594,11 @@ bool Compiler<Emitter>::VisitUnaryOperator(const UnaryOperator *E) {
if (DiscardResult) {
if (T == PT_Float)
return this->emitDecfPop(getFPOptions(E), E);
+ if (SubExpr->refersToBitField())
+ return DiscardResult ? this->emitDecPopBitfield(*T, E->canOverflow(),
+ getBitWidth(SubExpr), E)
+ : this->emitDecBitfield(*T, E->canOverflow(),
+ getBitWidth(SubExpr), E);
return this->emitDecPop(*T, E->canOverflow(), E);
}
@@ -6581,6 +6614,11 @@ bool Compiler<Emitter>::VisitUnaryOperator(const UnaryOperator *E) {
return false;
if (!this->emitStoreFloat(E))
return false;
+ } else if (SubExpr->refersToBitField()) {
+ assert(isIntegralType(*T));
+ if (!this->emitPreDecBitfield(*T, E->canOverflow(), getBitWidth(SubExpr),
+ E))
+ return false;
} else {
assert(isIntegralType(*T));
if (!this->emitPreDec(*T, E->canOverflow(), E))
diff --git a/clang/lib/AST/ByteCode/Interp.cpp b/clang/lib/AST/ByteCode/Interp.cpp
index a72282caf5e73..805ce6d698aae 100644
--- a/clang/lib/AST/ByteCode/Interp.cpp
+++ b/clang/lib/AST/ByteCode/Interp.cpp
@@ -1610,6 +1610,8 @@ bool Call(InterpState &S, CodePtr OpPC, const Function *Func,
if (!CheckCallDepth(S, OpPC))
return cleanup();
+ // Func->dump();
+
auto NewFrame = std::make_unique<InterpFrame>(S, Func, OpPC, VarArgSize);
InterpFrame *FrameBefore = S.Current;
S.Current = NewFrame.get();
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index d8529daf591ee..89f6fbefb1907 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -702,7 +702,7 @@ enum class IncDecOp {
template <typename T, IncDecOp Op, PushVal DoPush>
bool IncDecHelper(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
- bool CanOverflow) {
+ bool CanOverflow, UnsignedOrNone BitWidth = std::nullopt) {
assert(!Ptr.isDummy());
if (!S.inConstantContext()) {
@@ -725,12 +725,18 @@ bool IncDecHelper(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
if constexpr (Op == IncDecOp::Inc) {
if (!T::increment(Value, &Result) || !CanOverflow) {
- Ptr.deref<T>() = Result;
+ if (BitWidth)
+ Ptr.deref<T>() = Result.truncate(*BitWidth);
+ else
+ Ptr.deref<T>() = Result;
return true;
}
} else {
if (!T::decrement(Value, &Result) || !CanOverflow) {
- Ptr.deref<T>() = Result;
+ if (BitWidth)
+ Ptr.deref<T>() = Result.truncate(*BitWidth);
+ else
+ Ptr.deref<T>() = Result;
return true;
}
}
@@ -774,6 +780,17 @@ bool Inc(InterpState &S, CodePtr OpPC, bool CanOverflow) {
CanOverflow);
}
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool IncBitfield(InterpState &S, CodePtr OpPC, bool CanOverflow,
+ unsigned BitWidth) {
+ const Pointer &Ptr = S.Stk.pop<Pointer>();
+ if (!CheckLoad(S, OpPC, Ptr, AK_Increment))
+ return false;
+
+ return IncDecHelper<T, IncDecOp::Inc, PushVal::Yes>(S, OpPC, Ptr, CanOverflow,
+ BitWidth);
+}
+
/// 1) Pops a pointer from the stack
/// 2) Load the value from the pointer
/// 3) Writes the value increased by one back to the pointer
@@ -786,6 +803,17 @@ bool IncPop(InterpState &S, CodePtr OpPC, bool CanOverflow) {
return IncDecHelper<T, IncDecOp::Inc, PushVal::No>(S, OpPC, Ptr, CanOverflow);
}
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool IncPopBitfield(InterpState &S, CodePtr OpPC, bool CanOverflow,
+ uint32_t BitWidth) {
+ const Pointer &Ptr = S.Stk.pop<Pointer>();
+ if (!CheckLoad(S, OpPC, Ptr, AK_Increment))
+ return false;
+
+ return IncDecHelper<T, IncDecOp::Inc, PushVal::No>(S, OpPC, Ptr, CanOverflow,
+ BitWidth);
+}
+
template <PrimType Name, class T = typename PrimConv<Name>::T>
bool PreInc(InterpState &S, CodePtr OpPC, bool CanOverflow) {
const Pointer &Ptr = S.Stk.peek<Pointer>();
@@ -795,6 +823,17 @@ bool PreInc(InterpState &S, CodePtr OpPC, bool CanOverflow) {
return IncDecHelper<T, IncDecOp::Inc, PushVal::No>(S, OpPC, Ptr, CanOverflow);
}
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool PreIncBitfield(InterpState &S, CodePtr OpPC, bool CanOverflow,
+ uint32_t BitWidth) {
+ const Pointer &Ptr = S.Stk.peek<Pointer>();
+ if (!CheckLoad(S, OpPC, Ptr, AK_Increment))
+ return false;
+
+ return IncDecHelper<T, IncDecOp::Inc, PushVal::No>(S, OpPC, Ptr, CanOverflow,
+ BitWidth);
+}
+
/// 1) Pops a pointer from the stack
/// 2) Load the value from the pointer
/// 3) Writes the value decreased by one back to the pointer
@@ -808,6 +847,16 @@ bool Dec(InterpState &S, CodePtr OpPC, bool CanOverflow) {
return IncDecHelper<T, IncDecOp::Dec, PushVal::Yes>(S, OpPC, Ptr,
CanOverflow);
}
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool DecBitfield(InterpState &S, CodePtr OpPC, bool CanOverflow,
+ uint32_t BitWidth) {
+ const Pointer &Ptr = S.Stk.pop<Pointer>();
+ if (!CheckLoad(S, OpPC, Ptr, AK_Decrement))
+ return false;
+
+ return IncDecHelper<T, IncDecOp::Dec, PushVal::Yes>(S, OpPC, Ptr, CanOverflow,
+ BitWidth);
+}
/// 1) Pops a pointer from the stack
/// 2) Load the value from the pointer
@@ -821,6 +870,17 @@ bool DecPop(InterpState &S, CodePtr OpPC, bool CanOverflow) {
return IncDecHelper<T, IncDecOp::Dec, PushVal::No>(S, OpPC, Ptr, CanOverflow);
}
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool DecPopBitfield(InterpState &S, CodePtr OpPC, bool CanOverflow,
+ uint32_t BitWidth) {
+ const Pointer &Ptr = S.Stk.pop<Pointer>();
+ if (!CheckLoad(S, OpPC, Ptr, AK_Decrement))
+ return false;
+
+ return IncDecHelper<T, IncDecOp::Dec, PushVal::No>(S, OpPC, Ptr, CanOverflow,
+ BitWidth);
+}
+
template <PrimType Name, class T = typename PrimConv<Name>::T>
bool PreDec(InterpState &S, CodePtr OpPC, bool CanOverflow) {
const Pointer &Ptr = S.Stk.peek<Pointer>();
@@ -829,6 +889,16 @@ bool PreDec(InterpState &S, CodePtr OpPC, bool CanOverflow) {
return IncDecHelper<T, IncDecOp::Dec, PushVal::No>(S, OpPC, Ptr, CanOverflow);
}
+template <PrimType Name, class T = typename PrimConv<Name>::T>
+bool PreDecBitfield(InterpState &S, CodePtr OpPC, bool CanOverflow,
+ uint32_t BitWidth) {
+ const Pointer &Ptr = S.Stk.peek<Pointer>();
+ if (!CheckLoad(S, OpPC, Ptr, AK_Decrement))
+ return false;
+ return IncDecHelper<T, IncDecOp::Dec, PushVal::No>(S, OpPC, Ptr, CanOverflow,
+ BitWidth);
+}
+
template <IncDecOp Op, PushVal DoPush>
bool IncDecFloatHelper(InterpState &S, CodePtr OpPC, const Pointer &Ptr,
uint32_t FPOI) {
diff --git a/clang/lib/AST/ByteCode/Opcodes.td b/clang/lib/AST/ByteCode/Opcodes.td
index 532c4448e6f40..406feb57418fa 100644
--- a/clang/lib/AST/ByteCode/Opcodes.td
+++ b/clang/lib/AST/ByteCode/Opcodes.td
@@ -612,12 +612,25 @@ class OverflowOpcode : Opcode {
let HasGroup = 1;
}
+class OverflowBitfieldOpcode : Opcode {
+ let Types = [AluTypeClass];
+ let Args = [ArgBool, ArgUint32];
+ let HasGroup = 1;
+}
+
def Inc : OverflowOpcode;
+def IncBitfield : OverflowBitfieldOpcode;
def IncPop : OverflowOpcode;
+def IncPopBitfield : OverflowBitfieldOpcode;
def PreInc : OverflowOpcode;
+def PreIncBitfield : OverflowBitfieldOpcode;
+
def Dec : OverflowOpcode;
+def DecBitfield : OverflowBitfieldOpcode;
def DecPop : OverflowOpcode;
+def DecPopBitfield : OverflowBitfieldOpcode;
def PreDec : OverflowOpcode;
+def PreDecBitfield : OverflowBitfieldOpcode;
// Float increment and decrement.
def Incf: FloatOpcode;
diff --git a/clang/test/AST/ByteCode/bitfields.cpp b/clang/test/AST/ByteCode/bitfields.cpp
index df8d5678287d3..a58328286bd9a 100644
--- a/clang/test/AST/ByteCode/bitfields.cpp
+++ b/clang/test/AST/ByteCode/bitfields.cpp
@@ -128,3 +128,82 @@ namespace NonConstBitWidth {
// both-note {{read of non-const variable}}
};
}
+
+namespace IncDecOverflow {
+ constexpr bool test1() {
+ struct {unsigned u: 5; } a {};
+ a.u--;
+ return a.u == 31;
+ }
+ static_assert(test1(), "");
+
+ constexpr bool test2() {
+ struct {unsigned u: 5; } a {};
+ --a.u;
+ return a.u == 31;
+ }
+ static_assert(test2(), "");
+
+ constexpr bool test3() {
+ int x = 0;
+ struct {unsigned u: 5; } a {};
+ x = a.u--;
+ return a.u == 31;
+ }
+ static_assert(test3(), "");
+
+ constexpr bool test4() {
+ int x = 0;
+ struct {unsigned u: 5; } a {};
+ x = --a.u;
+ return a.u == 31;
+ }
+ static_assert(test4(), "");
+
+ constexpr bool test5() {
+ struct {unsigned u: 5; } a {};
+ a.u = 31;
+ ++a.u;
+
+ return a.u == 0;
+ }
+ static_assert(test5(), "");
+
+ constexpr bool test6() {
+ struct {unsigned u: 5; } a {};
+ a.u = 31;
+ ++a.u;
+
+ return a.u == 0;
+ }
+ static_assert(test6(), "");
+
+ constexpr bool test7() {
+ struct {unsigned u: 5; } a {};
+ a.u = 31;
+ a.u++;
+
+ return a.u == 0;
+ }
+ static_assert(test7(), "");
+
+ constexpr bool test8() {
+ int x = 0;
+ struct {unsigned u: 5; } a {};
+ a.u = 31;
+ x = a.u++;
+
+ return a.u == 0;
+ }
+ static_assert(test8(), "");
+
+ constexpr bool test9() {
+ int x = 0;
+ struct {unsigned u: 5; } a {};
+ a.u = 31;
+ x = ++a.u;
+
+ return a.u == 0;
+ }
+ static_assert(test9(), "");
+}
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dvbuka
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…vm#164445) and inc/dec operations. We need to truncate the new value to the bitfield bitwidth.
Lukacma
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…vm#164445) and inc/dec operations. We need to truncate the new value to the bitfield bitwidth.
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…vm#164445) and inc/dec operations. We need to truncate the new value to the bitfield bitwidth.
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and inc/dec operations. We need to truncate the new value to the bitfield bitwidth.