https://github.com/tbaederr created
https://github.com/llvm/llvm-project/pull/203671
We have several opcodes that can't fail, so add a flag to them indicating that
they always return `true` anyway.
This simplifies the generated code from e.g.
```c++
PRESERVE_NONE
static bool Interp_Activate(InterpState &S, CodePtr &PC) {
if (!Activate(S, PC))
return false;
#if USE_TAILCALLS
MUSTTAIL return InterpNext(S, PC);
#else
return true;
#endif
}
```
to
```c++
PRESERVE_NONE
static bool Interp_Activate(InterpState &S, CodePtr &PC) {
Activate(S, PC);
#if USE_TAILCALLS
MUSTTAIL return InterpNext(S, PC);
#else
return true;
#endif
}
```
>From 207c03fc97384c08e0bfb6ffdb56503edb710673 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <[email protected]>
Date: Fri, 12 Jun 2026 17:11:10 +0200
Subject: [PATCH] AlwaysSucceeds flag
---
clang/lib/AST/ByteCode/Opcodes.td | 67 +++++++++++++-------
clang/utils/TableGen/ClangOpcodesEmitter.cpp | 30 +++++++--
2 files changed, 69 insertions(+), 28 deletions(-)
diff --git a/clang/lib/AST/ByteCode/Opcodes.td
b/clang/lib/AST/ByteCode/Opcodes.td
index 09c616aa2ff1d..d45eef067b145 100644
--- a/clang/lib/AST/ByteCode/Opcodes.td
+++ b/clang/lib/AST/ByteCode/Opcodes.td
@@ -145,6 +145,11 @@ class Opcode {
bit HasCustomLink = 0;
bit HasCustomEval = 0;
bit HasGroup = 0;
+ bit CanFail = 1;
+}
+
+class SuccessOpcode : Opcode {
+ let CanFail = 0;
}
class AluOpcode : Opcode {
@@ -178,15 +183,14 @@ def Jt : JumpOpcode;
// [Bool] -> [], jumps if false.
def Jf : JumpOpcode;
-def PushIgnoreDiags : Opcode;
-def PopIgnoreDiags : Opcode;
+def PushIgnoreDiags : SuccessOpcode;
+def PopIgnoreDiags : SuccessOpcode;
+def StartInit : SuccessOpcode;
+def EndInit : SuccessOpcode;
-def StartInit : Opcode;
-def EndInit : Opcode;
-
-def StartSpeculation : Opcode;
-def EndSpeculation : Opcode;
+def StartSpeculation : SuccessOpcode;
+def EndSpeculation : SuccessOpcode;
def BCP : Opcode {
let ChangesPC = 1;
let HasCustomEval = 1;
@@ -204,12 +208,14 @@ def Ret : Opcode {
let CanReturn = 1;
let HasGroup = 1;
let HasCustomEval = 1;
+ let CanFail = 0;
}
// [] -> []
def RetVoid : Opcode {
let CanReturn = 1;
let ChangesPC = 1;
let HasCustomEval = 1;
+ let CanFail = 0;
}
// [Value] -> []
def RetValue : Opcode {
@@ -276,6 +282,7 @@ class ConstOpcode<Type Ty, ArgType ArgTy> : Opcode {
let Types = [SingletonTypeClass<Ty>];
let Args = [ArgTy];
let Name = "Const";
+ let CanFail = 0;
}
// [] -> [Integer]
@@ -292,20 +299,27 @@ def ConstIntAPS : ConstOpcode<IntAPS, ArgIntAPS>;
def ConstBool : ConstOpcode<Bool, ArgBool>;
def ConstFixedPoint : ConstOpcode<FixedPoint, ArgFixedPoint>;
-def ConstFloat : Opcode { let Args = [ArgFloat]; }
+def ConstFloat : Opcode {
+ let Args = [ArgFloat];
+ let CanFail = 0;
+}
// [] -> [Integer]
def Zero : Opcode {
let Types = [FixedSizeIntegralTypeClass];
let HasGroup = 1;
+ let CanFail = 0;
+
}
def ZeroIntAP : Opcode {
let Args = [ArgUint32];
+ let CanFail = 0;
}
def ZeroIntAPS : Opcode {
let Args = [ArgUint32];
+ let CanFail = 0;
}
// [] -> [Pointer]
@@ -313,6 +327,7 @@ def Null : Opcode {
let Types = [PtrTypeClass];
let Args = [ArgUint64, ArgTypePtr];
let HasGroup = 1;
+ let CanFail = 0;
}
//===----------------------------------------------------------------------===//
@@ -355,11 +370,11 @@ def CastMemberPtrDerivedPop : Opcode {
let Args = [ArgSint32, ArgRecordDecl];
}
-def FinishInitPop : Opcode;
-def FinishInit : Opcode;
-def FinishInitActivate : Opcode;
-def FinishInitActivatePop : Opcode;
-def FinishInitGlobal : Opcode;
+def FinishInitPop : SuccessOpcode;
+def FinishInit : SuccessOpcode;
+def FinishInitActivate : SuccessOpcode;
+def FinishInitActivatePop : SuccessOpcode;
+def FinishInitGlobal : SuccessOpcode;
def GetPtrDerivedPop : Opcode { let Args = [ArgUint32, ArgBool, ArgTypePtr]; }
@@ -385,9 +400,9 @@ def This : Opcode;
def RVOPtr : Opcode;
// [Pointer] -> [Pointer]
-def NarrowPtr : Opcode;
+def NarrowPtr : SuccessOpcode;
// [Pointer] -> [Pointer]
-def ExpandPtr : Opcode;
+def ExpandPtr : SuccessOpcode;
// [Pointer, Offset] -> [Pointer]
def ArrayElemPtr : Opcode {
let Types = [IntegralTypeClass];
@@ -452,6 +467,7 @@ def CheckEnumValue : Opcode {
let Args = [ArgEnumDecl];
let Types = [IntegralTypeClass];
let HasGroup = 1;
+ let CanFail = 0;
}
def CheckLiteralType : Opcode {
@@ -541,7 +557,7 @@ def StoreBitFieldPop : StoreBitFieldOpcode {}
def StoreBitFieldActivate : StoreBitFieldOpcode {}
def StoreBitFieldActivatePop : StoreBitFieldOpcode {}
-def Activate : Opcode {}
+def Activate : SuccessOpcode;
def ActivateThisField : Opcode { let Args = [ArgUint32]; }
// [Pointer, Value] -> []
@@ -592,6 +608,7 @@ def DecPtr : Opcode;
//===----------------------------------------------------------------------===//
def GetFnPtr : Opcode {
let Args = [ArgFunction];
+ let CanFail = 0;
}
def GetIntPtr : Opcode {
@@ -828,17 +845,20 @@ def GE : ComparisonOpcode;
def Pop : Opcode {
let Types = [AllTypeClass];
let HasGroup = 1;
+ let CanFail = 0;
}
// [Value] -> [Value, Value]
def Dup : Opcode {
let Types = [AllTypeClass];
let HasGroup = 1;
+ let CanFail = 0;
}
def Flip : Opcode {
let Types = [AllTypeClass, AllTypeClass];
let HasGroup = 1;
+ let CanFail = 0;
}
// [] -> []
@@ -852,7 +872,7 @@ def InvalidCast : Opcode {
def CheckDynamicCast : Opcode {}
def InvalidStore : Opcode { let Args = [ArgTypePtr]; }
-def CheckPseudoDtor : Opcode {}
+def CheckPseudoDtor : SuccessOpcode;
def InvalidDeclRef : Opcode {
let Args = [ArgDeclRef, ArgBool];
@@ -878,6 +898,7 @@ def ToMemberPtr : Opcode;
def CastMemberPtrPtr : Opcode;
def GetMemberPtr : Opcode {
let Args = [ArgValueDecl];
+ let CanFail = 0;
}
def GetMemberPtrBase : Opcode;
def GetMemberPtrDecl : Opcode;
@@ -943,8 +964,10 @@ def CheckDestruction : Opcode;
def CtorCheck : Opcode;
-def PushCC : Opcode { let Args = [ArgBool]; }
-def PopCC : Opcode;
-
-def PushMSVCCE : Opcode;
-def PopMSVCCE : Opcode;
+def PushCC : Opcode {
+ let Args = [ArgBool];
+ let CanFail = 0;
+}
+def PopCC : SuccessOpcode;
+def PushMSVCCE : SuccessOpcode;
+def PopMSVCCE : SuccessOpcode;
diff --git a/clang/utils/TableGen/ClangOpcodesEmitter.cpp
b/clang/utils/TableGen/ClangOpcodesEmitter.cpp
index 3192891801ae9..8d0ed4a1ccac5 100644
--- a/clang/utils/TableGen/ClangOpcodesEmitter.cpp
+++ b/clang/utils/TableGen/ClangOpcodesEmitter.cpp
@@ -127,6 +127,7 @@ void
ClangOpcodesEmitter::EmitInterpFnDispatchers(raw_ostream &OS, StringRef N,
bool CanReturn = R->getValueAsBit("CanReturn");
const auto &Args = R->getValueAsListOfDefs("Args");
bool ChangesPC = R->getValueAsBit("ChangesPC");
+ bool CanFail = R->getValueAsBit("CanFail");
if (Args.empty()) {
if (CanReturn) {
@@ -137,10 +138,19 @@ void
ClangOpcodesEmitter::EmitInterpFnDispatchers(raw_ostream &OS, StringRef N,
return;
}
- OS << " if (!" << N;
+ OS << " ";
+ if (CanFail)
+ OS << "if (!";
+
+ OS << N;
PrintTypes(OS, TS);
- OS << "(S, PC))\n";
- OS << " return false;\n";
+ OS << "(S, PC)";
+
+ if (CanFail)
+ OS << ") return false\n";
+
+ OS << ";\n";
+
OS << "#if USE_TAILCALLS\n";
OS << " MUSTTAIL return InterpNext(S, PC);\n";
OS << "#else\n";
@@ -168,7 +178,11 @@ void
ClangOpcodesEmitter::EmitInterpFnDispatchers(raw_ostream &OS, StringRef N,
OS << "ReadArg<" << Arg->getValueAsString("Name") << ">(S, PC);\n";
}
- OS << " if (!" << N;
+ OS << " ";
+ if (CanFail)
+ OS << "if (!";
+
+ OS << N;
PrintTypes(OS, TS);
OS << "(S";
if (ChangesPC)
@@ -177,9 +191,13 @@ void
ClangOpcodesEmitter::EmitInterpFnDispatchers(raw_ostream &OS, StringRef N,
OS << ", OpPC";
for (size_t I = 0, N = Args.size(); I < N; ++I)
OS << ", V" << I;
- OS << "))\n";
- OS << " return false;\n";
+ OS << ")";
+
+ if (CanFail)
+ OS << ") return false";
+
+ OS << ";\n";
OS << " }\n";
if (!CanReturn) {
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