tbaeder created this revision.
tbaeder added reviewers: aaron.ballman, erichkeane, shafik, cor3ntin.
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This commit is a bit ugly at the moment since I'm gathering feedback.
The APFloats we use to implement the `Floating` type might heap-allocate stuff
to represent large values. When we then later write those to bytecode (via
`BytecodeEmitter`, not `EvalEmitter`), that heap allocation is dangling.
So, for code like
constexpr long double f() {
const long double L = __LDBL_MAX__;
return L;
};
static_assert(f() == __LDBL_MAX__);
asan would complain:
READ of size 8 at 0x602000001610 thread T0
#0 0x7f525300b911 in llvm::APInt::tcAssign(unsigned long*, unsigned long
const*, unsigned int)
/home/tbaeder/code/llvm-project/llvm/lib/Support/APInt.cpp:2331:14
#1 0x7f5252f3f640 in
llvm::detail::IEEEFloat::copySignificand(llvm::detail::IEEEFloat const&)
/home/tbaeder/code/llvm-project/llvm/lib/Support/APFloat.cpp:878:3
#2 0x7f5252f3f42c in
llvm::detail::IEEEFloat::assign(llvm::detail::IEEEFloat const&)
/home/tbaeder/code/llvm-project/llvm/lib/Support/APFloat.cpp:871:5
#3 0x7f5252f46828 in
llvm::detail::IEEEFloat::IEEEFloat(llvm::detail::IEEEFloat const&)
/home/tbaeder/code/llvm-project/llvm/lib/Support/APFloat.cpp:1143:3
#4 0x7f5295e12913 in
llvm::APFloat::Storage::Storage(llvm::APFloat::Storage const&)
/home/tbaeder/code/llvm-project/llvm/include/llvm/ADT/APFloat.h:805:20
#5 0x7f5295e01d3a in llvm::APFloat::APFloat(llvm::APFloat const&)
/home/tbaeder/code/llvm-project/llvm/include/llvm/ADT/APFloat.h:928:3
#6 0x7f5297d56584 in
clang::interp::Floating::Floating(clang::interp::Floating const&)
/home/tbaeder/code/llvm-project/clang/lib/AST/Interp/Floating.h:27:7
#7 0x7f5297ea1fa0 in clang::interp::Floating
llvm::support::endian::read<clang::interp::Floating, 1ul>(void const*,
llvm::support::endianness)
/home/tbaeder/code/llvm-project/llvm/include/llvm/Support/Endian.h:70:32
#8 0x7f5297ea1e14 in clang::interp::Floating
llvm::support::endian::read<clang::interp::Floating,
(llvm::support::endianness)2, 1ul>(void const*)
/home/tbaeder/code/llvm-project/llvm/include/llvm/Support/Endian.h:77:10
#9 0x7f5297ea1d06 in
std::enable_if<!std::is_pointer<clang::interp::Floating>::value,
clang::interp::Floating>::type
clang::interp::CodePtr::read<clang::interp::Floating>()
/home/tbaeder/code/llvm-project/clang/lib/AST/Interp/Source.h:53:15
#10 0x7f52981e7601 in clang::interp::Floating
clang::interp::ReadArg<clang::interp::Floating>(clang::interp::InterpState&,
clang::interp::CodePtr&)
/home/tbaeder/code/llvm-project/clang/lib/AST/Interp/Interp.h:1894:17
[...]
freed by thread T0 here:
#0 0x3d2511 in operator delete[](void*)
(/home/tbaeder/code/llvm-project/build/bin/clang-17+0x3d2511) (BuildId:
88c1d01099b49a9ebf7bd913e201002fedf14f9b)
#1 0x7f5252f3eff9 in llvm::detail::IEEEFloat::freeSignificand()
/home/tbaeder/code/llvm-project/llvm/lib/Support/APFloat.cpp:861:5
#2 0x7f5252f46968 in llvm::detail::IEEEFloat::~IEEEFloat()
/home/tbaeder/code/llvm-project/llvm/lib/Support/APFloat.cpp:1150:27
#3 0x7f5295e11ad1 in llvm::APFloat::Storage::~Storage()
/home/tbaeder/code/llvm-project/llvm/include/llvm/ADT/APFloat.h:793:14
#4 0x7f5295e01d9c in llvm::APFloat::~APFloat()
/home/tbaeder/code/llvm-project/llvm/include/llvm/ADT/APFloat.h:931:22
#5 0x7f5297d5ddb8 in clang::interp::Floating::~Floating()
/home/tbaeder/code/llvm-project/clang/lib/AST/Interp/Floating.h:27:7
#6 0x7f5297ea1fe7 in clang::interp::Floating
llvm::support::endian::read<clang::interp::Floating, 1ul>(void const*,
llvm::support::endianness)
/home/tbaeder/code/llvm-project/llvm/include/llvm/Support/Endian.h:71:1
[...]
previously allocated by thread T0 here:
#0 0x3d1cb1 in operator new[](unsigned long)
(/home/tbaeder/code/llvm-project/build/bin/clang-17+0x3d1cb1) (BuildId:
88c1d01099b49a9ebf7bd913e201002fedf14f9b)
#1 0x7f5252f3ed6a in
llvm::detail::IEEEFloat::initialize(llvm::fltSemantics const*)
/home/tbaeder/code/llvm-project/llvm/lib/Support/APFloat.cpp:856:25
#2 0x7f5252f467e7 in
llvm::detail::IEEEFloat::IEEEFloat(llvm::detail::IEEEFloat const&)
/home/tbaeder/code/llvm-project/llvm/lib/Support/APFloat.cpp:1142:3
#3 0x7f5295e12913 in
llvm::APFloat::Storage::Storage(llvm::APFloat::Storage const&)
/home/tbaeder/code/llvm-project/llvm/include/llvm/ADT/APFloat.h:805:20
#4 0x7f5295e01d3a in llvm::APFloat::APFloat(llvm::APFloat const&)
/home/tbaeder/code/llvm-project/llvm/include/llvm/ADT/APFloat.h:928:3
#5 0x7f5297d56584 in
clang::interp::Floating::Floating(clang::interp::Floating const&)
/home/tbaeder/code/llvm-project/clang/lib/AST/Interp/Floating.h:27:7
#6 0x7f5297d17f93 in void
emit<clang::interp::Floating>(clang::interp::Program&,
std::__debug::vector<std::byte, std::allocator<std::byte>>&,
clang::interp::Floating const&, bool&)
/home/tbaeder/code/llvm-project/clang/lib/AST/Interp/ByteCodeEmitter.cpp:202:32
So, this patch adds specialized `readArg()` and `emit()` versions for
`Floating` that serializes the `APFloat`.
I'm not really sure if this is the best way to go though.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D155165
Files:
clang/lib/AST/Interp/ByteCodeEmitter.cpp
clang/lib/AST/Interp/Floating.h
clang/lib/AST/Interp/Interp.h
clang/lib/AST/Interp/Source.h
clang/test/AST/Interp/floats.cpp
Index: clang/test/AST/Interp/floats.cpp
===================================================================
--- clang/test/AST/Interp/floats.cpp
+++ clang/test/AST/Interp/floats.cpp
@@ -140,4 +140,11 @@
namespace LongDouble {
constexpr long double ld = 3.1425926539;
+
+ constexpr long double f() {
+ const long double L = __LDBL_MAX__;
+
+ return L;
+ };
+ static_assert(f() == __LDBL_MAX__);
}
Index: clang/lib/AST/Interp/Source.h
===================================================================
--- clang/lib/AST/Interp/Source.h
+++ clang/lib/AST/Interp/Source.h
@@ -60,6 +60,7 @@
/// Constructor used by Function to generate pointers.
CodePtr(const std::byte *Ptr) : Ptr(Ptr) {}
/// Pointer into the code owned by a function.
+public:
const std::byte *Ptr;
};
Index: clang/lib/AST/Interp/Interp.h
===================================================================
--- clang/lib/AST/Interp/Interp.h
+++ clang/lib/AST/Interp/Interp.h
@@ -1895,6 +1895,12 @@
}
}
+template <> inline Floating ReadArg<Floating>(InterpState &S, CodePtr &OpPC) {
+ Floating F = Floating::deserialize(OpPC.Ptr);
+ OpPC += align(F.bytesToSerialize());
+ return F;
+}
+
} // namespace interp
} // namespace clang
Index: clang/lib/AST/Interp/Floating.h
===================================================================
--- clang/lib/AST/Interp/Floating.h
+++ clang/lib/AST/Interp/Floating.h
@@ -124,6 +124,26 @@
llvm::StoreIntToMemory(API, (uint8_t *)Buff, bitWidth() / 8);
}
+ size_t bytesToSerialize() const {
+ return sizeof(llvm::fltSemantics *) +
+ (APFloat::semanticsSizeInBits(F.getSemantics()) / 8);
+ }
+
+ void serialize(std::byte *Buff) const {
+ // Semantics followed by an APInt.
+ *reinterpret_cast<const llvm::fltSemantics **>(Buff) = &F.getSemantics();
+
+ llvm::APInt API = F.bitcastToAPInt();
+ llvm::StoreIntToMemory(API, (uint8_t *)(Buff + sizeof(void *)),
+ bitWidth() / 8);
+ }
+
+ static Floating deserialize(const std::byte *Buff) {
+ const llvm::fltSemantics *Sem;
+ std::memcpy((void *)&Sem, Buff, sizeof(void *));
+ return bitcastFromMemory(Buff + sizeof(void *), *Sem);
+ }
+
// -------
static APFloat::opStatus add(const Floating &A, const Floating &B,
Index: clang/lib/AST/Interp/ByteCodeEmitter.cpp
===================================================================
--- clang/lib/AST/Interp/ByteCodeEmitter.cpp
+++ clang/lib/AST/Interp/ByteCodeEmitter.cpp
@@ -206,6 +206,25 @@
}
}
+template <>
+void emit(Program &P, std::vector<std::byte> &Code, const Floating &Val,
+ bool &Success) {
+ size_t Size = Val.bytesToSerialize();
+
+ if (Code.size() + Size > std::numeric_limits<unsigned>::max()) {
+ Success = false;
+ return;
+ }
+
+ // Access must be aligned!
+ size_t ValPos = align(Code.size());
+ Size = align(Size);
+ assert(aligned(ValPos + Size));
+ Code.resize(ValPos + Size);
+
+ Val.serialize(Code.data() + ValPos);
+}
+
template <typename... Tys>
bool ByteCodeEmitter::emitOp(Opcode Op, const Tys &... Args, const SourceInfo &SI) {
bool Success = true;
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