https://github.com/tbaederr created
https://github.com/llvm/llvm-project/pull/125253
Instead of heap-allocating it. This is similar to what the current interpeter
does. In C, we have no function calls, so the extra heap allocation never makes
sense.
>From 26c07a4b0b5c85de8fa3ab394ece750dac905eed Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbae...@redhat.com>
Date: Fri, 31 Jan 2025 09:34:32 +0100
Subject: [PATCH] [clang][bytecode] Stack-allocate bottom function frame
Instead of heap-allocating it. This is similar to what the current
interpeter does. In C, we have no function calls, so the extra heap
allocation never makes sense.
---
clang/lib/AST/ByteCode/EvalEmitter.cpp | 7 +++----
clang/lib/AST/ByteCode/EvalEmitter.h | 2 ++
clang/lib/AST/ByteCode/Interp.h | 4 ++--
clang/lib/AST/ByteCode/InterpFrame.cpp | 4 ++++
clang/lib/AST/ByteCode/InterpFrame.h | 12 ++++++++++++
clang/lib/AST/ByteCode/InterpState.cpp | 2 +-
6 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/clang/lib/AST/ByteCode/EvalEmitter.cpp
b/clang/lib/AST/ByteCode/EvalEmitter.cpp
index 9763fe89b73742..3f64aea4183f64 100644
--- a/clang/lib/AST/ByteCode/EvalEmitter.cpp
+++ b/clang/lib/AST/ByteCode/EvalEmitter.cpp
@@ -17,10 +17,9 @@ using namespace clang::interp;
EvalEmitter::EvalEmitter(Context &Ctx, Program &P, State &Parent,
InterpStack &Stk)
- : Ctx(Ctx), P(P), S(Parent, P, Stk, Ctx, this), EvalResult(&Ctx) {
- // Create a dummy frame for the interpreter which does not have locals.
- S.Current =
- new InterpFrame(S, /*Func=*/nullptr, /*Caller=*/nullptr, CodePtr(), 0);
+ : Ctx(Ctx), P(P), S(Parent, P, Stk, Ctx, this), EvalResult(&Ctx),
+ BottomFrame(S) {
+ S.Current = &BottomFrame;
}
EvalEmitter::~EvalEmitter() {
diff --git a/clang/lib/AST/ByteCode/EvalEmitter.h
b/clang/lib/AST/ByteCode/EvalEmitter.h
index e7c9e80d75d934..0b58b100f85fad 100644
--- a/clang/lib/AST/ByteCode/EvalEmitter.h
+++ b/clang/lib/AST/ByteCode/EvalEmitter.h
@@ -125,6 +125,8 @@ class EvalEmitter : public SourceMapper {
/// Active block which should be executed.
LabelTy ActiveLabel = 0;
+ InterpFrame BottomFrame;
+
protected:
#define GET_EVAL_PROTO
#include "Opcodes.inc"
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index 063970afec9e35..91a82a25944fb5 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -325,11 +325,11 @@ bool Ret(InterpState &S, CodePtr &PC) {
if (InterpFrame *Caller = S.Current->Caller) {
PC = S.Current->getRetPC();
- delete S.Current;
+ InterpFrame::free(S.Current);
S.Current = Caller;
S.Stk.push<T>(Ret);
} else {
- delete S.Current;
+ InterpFrame::free(S.Current);
S.Current = nullptr;
// The topmost frame should come from an EvalEmitter,
// which has its own implementation of the Ret<> instruction.
diff --git a/clang/lib/AST/ByteCode/InterpFrame.cpp
b/clang/lib/AST/ByteCode/InterpFrame.cpp
index 20f67d9b1fd425..cfcc9dc80d5353 100644
--- a/clang/lib/AST/ByteCode/InterpFrame.cpp
+++ b/clang/lib/AST/ByteCode/InterpFrame.cpp
@@ -23,6 +23,10 @@
using namespace clang;
using namespace clang::interp;
+InterpFrame::InterpFrame(InterpState &S)
+ : Caller(nullptr), S(S), Depth(0), Func(nullptr), RetPC(CodePtr()),
+ ArgSize(0), Args(nullptr), FrameOffset(0), IsBottom(true) {}
+
InterpFrame::InterpFrame(InterpState &S, const Function *Func,
InterpFrame *Caller, CodePtr RetPC, unsigned ArgSize)
: Caller(Caller), S(S), Depth(Caller ? Caller->Depth + 1 : 0), Func(Func),
diff --git a/clang/lib/AST/ByteCode/InterpFrame.h
b/clang/lib/AST/ByteCode/InterpFrame.h
index 7cfc3ac68b4f3e..426dbb0e396d35 100644
--- a/clang/lib/AST/ByteCode/InterpFrame.h
+++ b/clang/lib/AST/ByteCode/InterpFrame.h
@@ -28,6 +28,9 @@ class InterpFrame final : public Frame {
/// The frame of the previous function.
InterpFrame *Caller;
+ /// Bottom Frame.
+ InterpFrame(InterpState &S);
+
/// Creates a new frame for a method call.
InterpFrame(InterpState &S, const Function *Func, InterpFrame *Caller,
CodePtr RetPC, unsigned ArgSize);
@@ -42,6 +45,12 @@ class InterpFrame final : public Frame {
/// Destroys the frame, killing all live pointers to stack slots.
~InterpFrame();
+ static void free(InterpFrame *F) {
+ if (F->isBottomFrame())
+ return;
+ delete F;
+ }
+
/// Invokes the destructors for a scope.
void destroy(unsigned Idx);
void initScope(unsigned Idx);
@@ -119,6 +128,8 @@ class InterpFrame final : public Frame {
bool isStdFunction() const;
+ bool isBottomFrame() const { return IsBottom; }
+
void dump() const { dump(llvm::errs(), 0); }
void dump(llvm::raw_ostream &OS, unsigned Indent = 0) const;
@@ -167,6 +178,7 @@ class InterpFrame final : public Frame {
const size_t FrameOffset;
/// Mapping from arg offsets to their argument blocks.
llvm::DenseMap<unsigned, std::unique_ptr<char[]>> Params;
+ bool IsBottom = false;
};
} // namespace interp
diff --git a/clang/lib/AST/ByteCode/InterpState.cpp
b/clang/lib/AST/ByteCode/InterpState.cpp
index 287c3bd3bca3a5..8aa44e48842e96 100644
--- a/clang/lib/AST/ByteCode/InterpState.cpp
+++ b/clang/lib/AST/ByteCode/InterpState.cpp
@@ -27,7 +27,7 @@ bool InterpState::inConstantContext() const {
}
InterpState::~InterpState() {
- while (Current) {
+ while (Current && !Current->isBottomFrame()) {
InterpFrame *Next = Current->Caller;
delete Current;
Current = Next;
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