[clang] [clang codegen][NFC] Delete dead code in constant emission. (PR #90106)
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Thu Apr 25 12:17:19 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-codegen
Author: Eli Friedman (efriedma-quic)
<details>
<summary>Changes</summary>
This code was apparently added in de0fe07eef, but never used.
I think more of the related code might actually dead, but I haven't tried to dig more deeply.
---
Full diff: https://github.com/llvm/llvm-project/pull/90106.diff
4 Files Affected:
- (modified) clang/lib/CodeGen/CGExprAgg.cpp (+1-1)
- (modified) clang/lib/CodeGen/CGExprConstant.cpp (+4-34)
- (modified) clang/lib/CodeGen/CodeGenModule.cpp (+4-6)
- (modified) clang/lib/CodeGen/ConstantEmitter.h (+3-27)
``````````diff
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 355fec42be4489..318d0e031095ea 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -537,7 +537,7 @@ void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
ConstantEmitter Emitter(CGF);
LangAS AS = ArrayQTy.getAddressSpace();
if (llvm::Constant *C =
- Emitter.tryEmitForInitializer(ExprToVisit, AS, ArrayQTy)) {
+ Emitter.tryEmitForInitializer(ExprToVisit, ArrayQTy)) {
auto GV = new llvm::GlobalVariable(
CGM.getModule(), C->getType(),
/* isConstant= */ true, llvm::GlobalValue::PrivateLinkage, C,
diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
index c924660c5a91c8..91582c3257934c 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -926,7 +926,7 @@ tryEmitGlobalCompoundLiteral(ConstantEmitter &emitter,
LangAS addressSpace = E->getType().getAddressSpace();
llvm::Constant *C = emitter.tryEmitForInitializer(E->getInitializer(),
- addressSpace, E->getType());
+ E->getType());
if (!C) {
assert(!E->isFileScope() &&
"file-scope compound literal did not have constant initializer!");
@@ -1474,54 +1474,24 @@ ConstantEmitter::emitAbstract(SourceLocation loc, const APValue &value,
}
llvm::Constant *ConstantEmitter::tryEmitForInitializer(const VarDecl &D) {
- initializeNonAbstract(D.getType().getAddressSpace());
+ initializeNonAbstract();
return markIfFailed(tryEmitPrivateForVarInit(D));
}
llvm::Constant *ConstantEmitter::tryEmitForInitializer(const Expr *E,
- LangAS destAddrSpace,
QualType destType) {
- initializeNonAbstract(destAddrSpace);
+ initializeNonAbstract();
return markIfFailed(tryEmitPrivateForMemory(E, destType));
}
llvm::Constant *ConstantEmitter::emitForInitializer(const APValue &value,
- LangAS destAddrSpace,
QualType destType) {
- initializeNonAbstract(destAddrSpace);
+ initializeNonAbstract();
auto C = tryEmitPrivateForMemory(value, destType);
assert(C && "couldn't emit constant value non-abstractly?");
return C;
}
-llvm::GlobalValue *ConstantEmitter::getCurrentAddrPrivate() {
- assert(!Abstract && "cannot get current address for abstract constant");
-
-
-
- // Make an obviously ill-formed global that should blow up compilation
- // if it survives.
- auto global = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty, true,
- llvm::GlobalValue::PrivateLinkage,
- /*init*/ nullptr,
- /*name*/ "",
- /*before*/ nullptr,
- llvm::GlobalVariable::NotThreadLocal,
- CGM.getContext().getTargetAddressSpace(DestAddressSpace));
-
- PlaceholderAddresses.push_back(std::make_pair(nullptr, global));
-
- return global;
-}
-
-void ConstantEmitter::registerCurrentAddrPrivate(llvm::Constant *signal,
- llvm::GlobalValue *placeholder) {
- assert(!PlaceholderAddresses.empty());
- assert(PlaceholderAddresses.back().first == nullptr);
- assert(PlaceholderAddresses.back().second == placeholder);
- PlaceholderAddresses.back().first = signal;
-}
-
namespace {
struct ReplacePlaceholders {
CodeGenModule &CGM;
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 0c447b20cef40d..a6592311c7a01f 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3503,8 +3503,7 @@ ConstantAddress CodeGenModule::GetAddrOfMSGuidDecl(const MSGuidDecl *GD) {
if (!V.isAbsent()) {
// If possible, emit the APValue version of the initializer. In particular,
// this gets the type of the constant right.
- Init = Emitter.emitForInitializer(
- GD->getAsAPValue(), GD->getType().getAddressSpace(), GD->getType());
+ Init = Emitter.emitForInitializer(GD->getAsAPValue(), GD->getType());
} else {
// As a fallback, directly construct the constant.
// FIXME: This may get padding wrong under esoteric struct layout rules.
@@ -3552,8 +3551,7 @@ ConstantAddress CodeGenModule::GetAddrOfUnnamedGlobalConstantDecl(
const APValue &V = GCD->getValue();
assert(!V.isAbsent());
- Init = Emitter.emitForInitializer(V, GCD->getType().getAddressSpace(),
- GCD->getType());
+ Init = Emitter.emitForInitializer(V, GCD->getType());
auto *GV = new llvm::GlobalVariable(getModule(), Init->getType(),
/*isConstant=*/true,
@@ -3578,7 +3576,7 @@ ConstantAddress CodeGenModule::GetAddrOfTemplateParamObject(
ConstantEmitter Emitter(*this);
llvm::Constant *Init = Emitter.emitForInitializer(
- TPO->getValue(), TPO->getType().getAddressSpace(), TPO->getType());
+ TPO->getValue(), TPO->getType());
if (!Init) {
ErrorUnsupported(TPO, "template parameter object");
@@ -6520,7 +6518,7 @@ ConstantAddress CodeGenModule::GetAddrOfGlobalTemporary(
if (Value) {
// The temporary has a constant initializer, use it.
emitter.emplace(*this);
- InitialValue = emitter->emitForInitializer(*Value, AddrSpace,
+ InitialValue = emitter->emitForInitializer(*Value,
MaterializedType);
Constant =
MaterializedType.isConstantStorage(getContext(), /*ExcludeCtor*/ Value,
diff --git a/clang/lib/CodeGen/ConstantEmitter.h b/clang/lib/CodeGen/ConstantEmitter.h
index a55da0dcad7921..52009adbf0ebe4 100644
--- a/clang/lib/CodeGen/ConstantEmitter.h
+++ b/clang/lib/CodeGen/ConstantEmitter.h
@@ -40,10 +40,6 @@ class ConstantEmitter {
/// Whether we're in a constant context.
bool InConstantContext = false;
- /// The AST address space where this (non-abstract) initializer is going.
- /// Used for generating appropriate placeholders.
- LangAS DestAddressSpace = LangAS::Default;
-
llvm::SmallVector<std::pair<llvm::Constant *, llvm::GlobalVariable*>, 4>
PlaceholderAddresses;
@@ -73,10 +69,8 @@ class ConstantEmitter {
/// Try to emit the initiaizer of the given declaration as an abstract
/// constant. If this succeeds, the emission must be finalized.
llvm::Constant *tryEmitForInitializer(const VarDecl &D);
- llvm::Constant *tryEmitForInitializer(const Expr *E, LangAS destAddrSpace,
- QualType destType);
- llvm::Constant *emitForInitializer(const APValue &value, LangAS destAddrSpace,
- QualType destType);
+ llvm::Constant *tryEmitForInitializer(const Expr *E, QualType destType);
+ llvm::Constant *emitForInitializer(const APValue &value, QualType destType);
void finalize(llvm::GlobalVariable *global);
@@ -138,28 +132,10 @@ class ConstantEmitter {
llvm::Constant *tryEmitPrivate(const APValue &value, QualType T);
llvm::Constant *tryEmitPrivateForMemory(const APValue &value, QualType T);
- /// Get the address of the current location. This is a constant
- /// that will resolve, after finalization, to the address of the
- /// 'signal' value that is registered with the emitter later.
- llvm::GlobalValue *getCurrentAddrPrivate();
-
- /// Register a 'signal' value with the emitter to inform it where to
- /// resolve a placeholder. The signal value must be unique in the
- /// initializer; it might, for example, be the address of a global that
- /// refers to the current-address value in its own initializer.
- ///
- /// Uses of the placeholder must be properly anchored before finalizing
- /// the emitter, e.g. by being installed as the initializer of a global
- /// variable. That is, it must be possible to replaceAllUsesWith
- /// the placeholder with the proper address of the signal.
- void registerCurrentAddrPrivate(llvm::Constant *signal,
- llvm::GlobalValue *placeholder);
-
private:
- void initializeNonAbstract(LangAS destAS) {
+ void initializeNonAbstract() {
assert(!InitializedNonAbstract);
InitializedNonAbstract = true;
- DestAddressSpace = destAS;
}
llvm::Constant *markIfFailed(llvm::Constant *init) {
if (!init)
``````````
</details>
https://github.com/llvm/llvm-project/pull/90106
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