[IR] BlockAddress doesn't use BasicBlock#200772
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aengelke merged 2 commits intoJun 1, 2026
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Created using spr 1.3.8-wip
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@llvm/pr-subscribers-llvm-ir Author: Alexis Engelke (aengelke) ChangesBlockAddress is the only non-terminator user of a BasicBlock, and it This should also make uselistorder_bb obsolete. 22 Files Affected:
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 00cfcb20da74c..d998b6a66e168 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -4325,16 +4325,11 @@ Use-list directives may appear at function scope or global scope. They are not
instructions, and have no effect on the semantics of the IR. When they're at
function scope, they must appear after the terminator of the final basic block.
-If basic blocks have their address taken via ``blockaddress()`` expressions,
-``uselistorder_bb`` can be used to reorder their use-lists from outside their
-function's scope.
-
:Syntax:
::
uselistorder <ty> <value>, { <order-indexes> }
- uselistorder_bb @function, %block { <order-indexes> }
:Examples:
@@ -4355,7 +4350,6 @@ function's scope.
uselistorder ptr @global, { 1, 2, 0 }
uselistorder i32 7, { 1, 0 }
uselistorder i32 (i32) @bar, { 1, 0 }
- uselistorder_bb @foo, %bb, { 5, 1, 3, 2, 0, 4 }
.. _source_filename:
diff --git a/llvm/include/llvm/AsmParser/LLParser.h b/llvm/include/llvm/AsmParser/LLParser.h
index b545b7886e26e..8eda81d13583b 100644
--- a/llvm/include/llvm/AsmParser/LLParser.h
+++ b/llvm/include/llvm/AsmParser/LLParser.h
@@ -706,7 +706,6 @@ namespace llvm {
// Use-list order directives.
bool parseUseListOrder(PerFunctionState *PFS = nullptr);
- bool parseUseListOrderBB();
bool parseUseListOrderIndexes(SmallVectorImpl<unsigned> &Indexes);
bool sortUseListOrder(Value *V, ArrayRef<unsigned> Indexes, SMLoc Loc);
};
diff --git a/llvm/include/llvm/AsmParser/LLToken.h b/llvm/include/llvm/AsmParser/LLToken.h
index 426ca35ededb6..d2766a05ce9ba 100644
--- a/llvm/include/llvm/AsmParser/LLToken.h
+++ b/llvm/include/llvm/AsmParser/LLToken.h
@@ -388,7 +388,6 @@ enum Kind {
// Use-list order directives.
kw_uselistorder,
- kw_uselistorder_bb,
// Summary index keywords
kw_path,
diff --git a/llvm/include/llvm/IR/CFG.h b/llvm/include/llvm/IR/CFG.h
index c68c2f2e53d81..29a5cc7bf9348 100644
--- a/llvm/include/llvm/IR/CFG.h
+++ b/llvm/include/llvm/IR/CFG.h
@@ -51,23 +51,9 @@ class PredIterator {
using Self = PredIterator<Ptr, USE_iterator>;
USE_iterator It;
- inline void advancePastNonTerminators() {
- // Loop to ignore non-terminator uses (for example BlockAddresses).
- while (!It.atEnd()) {
- if (auto *Inst = dyn_cast<Instruction>(*It)) {
- assert(Inst->isTerminator() && "BasicBlock used in non-terminator");
- break;
- }
-
- ++It;
- }
- }
-
public:
PredIterator() = default;
- explicit inline PredIterator(Ptr *bb) : It(bb->user_begin()) {
- advancePastNonTerminators();
- }
+ explicit inline PredIterator(Ptr *bb) : It(bb->user_begin()) {}
inline PredIterator(Ptr *bb, bool) : It(bb->user_end()) {}
inline bool operator==(const Self& x) const { return It == x.It; }
@@ -75,13 +61,15 @@ class PredIterator {
inline reference operator*() const {
assert(!It.atEnd() && "pred_iterator out of range!");
- return cast<Instruction>(*It)->getParent();
+ auto *I = cast<Instruction>(*It);
+ assert(I->isTerminator() && "BasicBlock used in non-terminator");
+ return I->getParent();
}
inline pointer *operator->() const { return &operator*(); }
inline Self& operator++() { // Preincrement
assert(!It.atEnd() && "pred_iterator out of range!");
- ++It; advancePastNonTerminators();
+ ++It;
return *this;
}
diff --git a/llvm/include/llvm/IR/Constants.h b/llvm/include/llvm/IR/Constants.h
index 3b37d3fe86c70..d1a65db0af31f 100644
--- a/llvm/include/llvm/IR/Constants.h
+++ b/llvm/include/llvm/IR/Constants.h
@@ -1082,7 +1082,9 @@ class ConstantTargetNone final : public ConstantData {
class BlockAddress final : public Constant {
friend class Constant;
- constexpr static IntrusiveOperandsAllocMarker AllocMarker{1};
+ constexpr static IntrusiveOperandsAllocMarker AllocMarker{0};
+
+ BasicBlock *Block;
BlockAddress(Type *Ty, BasicBlock *BB);
@@ -1114,7 +1116,7 @@ class BlockAddress final : public Constant {
/// Transparently provide more efficient getOperand methods.
DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
- BasicBlock *getBasicBlock() const { return cast<BasicBlock>(Op<0>().get()); }
+ BasicBlock *getBasicBlock() const { return Block; }
Function *getFunction() const { return getBasicBlock()->getParent(); }
/// Methods for support type inquiry through isa, cast, and dyn_cast:
@@ -1125,7 +1127,7 @@ class BlockAddress final : public Constant {
template <>
struct OperandTraits<BlockAddress>
- : public FixedNumOperandTraits<BlockAddress, 1> {};
+ : public FixedNumOperandTraits<BlockAddress, 0> {};
DEFINE_TRANSPARENT_OPERAND_ACCESSORS(BlockAddress, Value)
diff --git a/llvm/lib/AsmParser/LLLexer.cpp b/llvm/lib/AsmParser/LLLexer.cpp
index b1a0a71fcc3ae..069a180056488 100644
--- a/llvm/lib/AsmParser/LLLexer.cpp
+++ b/llvm/lib/AsmParser/LLLexer.cpp
@@ -801,7 +801,6 @@ lltok::Kind LLLexer::LexIdentifier() {
// Use-list order directives.
KEYWORD(uselistorder);
- KEYWORD(uselistorder_bb);
KEYWORD(personality);
KEYWORD(cleanup);
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 848132538b450..e2d0c85123adc 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -632,10 +632,6 @@ bool LLParser::parseTopLevelEntities() {
if (parseUseListOrder())
return true;
break;
- case lltok::kw_uselistorder_bb:
- if (parseUseListOrderBB())
- return true;
- break;
}
}
}
@@ -9470,53 +9466,6 @@ bool LLParser::parseUseListOrder(PerFunctionState *PFS) {
return sortUseListOrder(V, Indexes, Loc);
}
-/// parseUseListOrderBB
-/// ::= 'uselistorder_bb' @foo ',' %bar ',' UseListOrderIndexes
-bool LLParser::parseUseListOrderBB() {
- assert(Lex.getKind() == lltok::kw_uselistorder_bb);
- SMLoc Loc = Lex.getLoc();
- Lex.Lex();
-
- ValID Fn, Label;
- SmallVector<unsigned, 16> Indexes;
- if (parseValID(Fn, /*PFS=*/nullptr) ||
- parseToken(lltok::comma, "expected comma in uselistorder_bb directive") ||
- parseValID(Label, /*PFS=*/nullptr) ||
- parseToken(lltok::comma, "expected comma in uselistorder_bb directive") ||
- parseUseListOrderIndexes(Indexes))
- return true;
-
- // Check the function.
- GlobalValue *GV;
- if (Fn.Kind == ValID::t_GlobalName)
- GV = M->getNamedValue(Fn.StrVal);
- else if (Fn.Kind == ValID::t_GlobalID)
- GV = NumberedVals.get(Fn.UIntVal);
- else
- return error(Fn.Loc, "expected function name in uselistorder_bb");
- if (!GV)
- return error(Fn.Loc,
- "invalid function forward reference in uselistorder_bb");
- auto *F = dyn_cast<Function>(GV);
- if (!F)
- return error(Fn.Loc, "expected function name in uselistorder_bb");
- if (F->isDeclaration())
- return error(Fn.Loc, "invalid declaration in uselistorder_bb");
-
- // Check the basic block.
- if (Label.Kind == ValID::t_LocalID)
- return error(Label.Loc, "invalid numeric label in uselistorder_bb");
- if (Label.Kind != ValID::t_LocalName)
- return error(Label.Loc, "expected basic block name in uselistorder_bb");
- Value *V = F->getValueSymbolTable()->lookup(Label.StrVal);
- if (!V)
- return error(Label.Loc, "invalid basic block in uselistorder_bb");
- if (!isa<BasicBlock>(V))
- return error(Label.Loc, "expected basic block in uselistorder_bb");
-
- return sortUseListOrder(V, Indexes, Loc);
-}
-
/// ModuleEntry
/// ::= 'module' ':' '(' 'path' ':' STRINGCONSTANT ',' 'hash' ':' Hash ')'
/// Hash ::= '(' UInt32 ',' UInt32 ',' UInt32 ',' UInt32 ',' UInt32 ')'
diff --git a/llvm/lib/CodeGen/IndirectBrExpandPass.cpp b/llvm/lib/CodeGen/IndirectBrExpandPass.cpp
index d41b7a49d3dc2..087c333684734 100644
--- a/llvm/lib/CodeGen/IndirectBrExpandPass.cpp
+++ b/llvm/lib/CodeGen/IndirectBrExpandPass.cpp
@@ -135,23 +135,11 @@ bool runImpl(Function &F, const TargetLowering *TLI, DomTreeUpdater *DTU) {
if (!IndirectBrSuccs.count(&BB))
continue;
- auto IsBlockAddressUse = [&](const Use &U) {
- return isa<BlockAddress>(U.getUser());
- };
- auto BlockAddressUseIt = llvm::find_if(BB.uses(), IsBlockAddressUse);
- if (BlockAddressUseIt == BB.use_end())
- continue;
-
- assert(std::none_of(std::next(BlockAddressUseIt), BB.use_end(),
- IsBlockAddressUse) &&
- "There should only ever be a single blockaddress use because it is "
- "a constant and should be uniqued.");
-
- auto *BA = cast<BlockAddress>(BlockAddressUseIt->getUser());
+ auto *BA = BlockAddress::lookup(&BB);
// Skip if the constant was formed but ended up not being used (due to DCE
// or whatever).
- if (!BA->isConstantUsed())
+ if (!BA || !BA->isConstantUsed())
continue;
// Compute the index we want to use for this basic block. We can't use zero
diff --git a/llvm/lib/IR/BasicBlock.cpp b/llvm/lib/IR/BasicBlock.cpp
index da97b26f7cec5..d611e9c2d0a96 100644
--- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -175,8 +175,7 @@ BasicBlock::~BasicBlock() {
// is no indirect branch). Handle these cases by zapping the BlockAddress
// nodes. There are no other possible uses at this point.
if (hasAddressTaken()) {
- assert(!use_empty() && "There should be at least one blockaddress!");
- BlockAddress *BA = cast<BlockAddress>(user_back());
+ BlockAddress *BA = BlockAddress::lookup(this);
Constant *Replacement = ConstantInt::get(Type::getInt32Ty(getContext()), 1);
BA->replaceAllUsesWith(
diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 1001ad71471bb..cadb48b1a649b 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -2056,7 +2056,7 @@ BlockAddress *BlockAddress::get(Function *F, BasicBlock *BB) {
BlockAddress::BlockAddress(Type *Ty, BasicBlock *BB)
: Constant(Ty, Value::BlockAddressVal, AllocMarker) {
- setOperand(0, BB);
+ Block = BB;
BB->setHasAddressTaken(true);
}
@@ -2089,7 +2089,7 @@ Value *BlockAddress::handleOperandChangeImpl(Value *From, Value *To) {
// erase invalidates iterators/references, hence the duplicate NewBB lookup.
getContext().pImpl->BlockAddresses.erase(getBasicBlock());
getContext().pImpl->BlockAddresses[NewBB] = this;
- setOperand(0, NewBB);
+ Block = NewBB;
getBasicBlock()->setHasAddressTaken(true);
// If we just want to keep the existing value, then return null.
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index f5a501897f0bb..11bc6596bdb32 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -542,8 +542,11 @@ void Value::doRAUW(Value *New, ReplaceMetadataUses ReplaceMetaUses) {
U.set(New);
}
- if (BasicBlock *BB = dyn_cast<BasicBlock>(this))
+ if (BasicBlock *BB = dyn_cast<BasicBlock>(this)) {
BB->replaceSuccessorsPhiUsesWith(cast<BasicBlock>(New));
+ if (BB->hasAddressTaken())
+ BlockAddress::lookup(BB)->handleOperandChange(this, New);
+ }
}
void Value::replaceAllUsesWith(Value *New) {
diff --git a/llvm/test/Assembler/invalid-uselistorder_bb-float-literal.ll b/llvm/test/Assembler/invalid-uselistorder_bb-float-literal.ll
deleted file mode 100644
index f6d1a08431e85..0000000000000
--- a/llvm/test/Assembler/invalid-uselistorder_bb-float-literal.ll
+++ /dev/null
@@ -1,11 +0,0 @@
-; RUN: not llvm-as < %s -disable-output 2>&1 | FileCheck %s
-; CHECK: error: unexpected floating-point literal
-
-@ba1 = constant ptr blockaddress (@foo, %1)
-
-define void @foo() {
- br label %1
- unreachable
-}
-
-uselistorder_bb 1.0, %1, { 1, 0 }
diff --git a/llvm/test/Assembler/invalid-uselistorder_bb-missing-bb.ll b/llvm/test/Assembler/invalid-uselistorder_bb-missing-bb.ll
deleted file mode 100644
index bd12faa85b6b1..0000000000000
--- a/llvm/test/Assembler/invalid-uselistorder_bb-missing-bb.ll
+++ /dev/null
@@ -1,6 +0,0 @@
-; RUN: not llvm-as < %s -disable-output 2>&1 | FileCheck %s
-; CHECK: error: invalid basic block in uselistorder_bb
-define void @foo() {
- unreachable
-}
-uselistorder_bb @foo, %bb, { 1, 0 }
diff --git a/llvm/test/Assembler/invalid-uselistorder_bb-missing-body.ll b/llvm/test/Assembler/invalid-uselistorder_bb-missing-body.ll
deleted file mode 100644
index 0fbc3a8338801..0000000000000
--- a/llvm/test/Assembler/invalid-uselistorder_bb-missing-body.ll
+++ /dev/null
@@ -1,4 +0,0 @@
-; RUN: not llvm-as < %s -disable-output 2>&1 | FileCheck %s
-; CHECK: error: invalid declaration in uselistorder_bb
-declare void @foo()
-uselistorder_bb @foo, %bb, { 1, 0 }
diff --git a/llvm/test/Assembler/invalid-uselistorder_bb-missing-func.ll b/llvm/test/Assembler/invalid-uselistorder_bb-missing-func.ll
deleted file mode 100644
index 5a1466fcbc86d..0000000000000
--- a/llvm/test/Assembler/invalid-uselistorder_bb-missing-func.ll
+++ /dev/null
@@ -1,3 +0,0 @@
-; RUN: not llvm-as < %s -disable-output 2>&1 | FileCheck %s
-; CHECK: error: invalid function forward reference in uselistorder_bb
-uselistorder_bb @foo, %bb, { 1, 0 }
diff --git a/llvm/test/Assembler/invalid-uselistorder_bb-not-bb.ll b/llvm/test/Assembler/invalid-uselistorder_bb-not-bb.ll
deleted file mode 100644
index e59e7543ae7d9..0000000000000
--- a/llvm/test/Assembler/invalid-uselistorder_bb-not-bb.ll
+++ /dev/null
@@ -1,6 +0,0 @@
-; RUN: not llvm-as < %s -disable-output 2>&1 | FileCheck %s
-; CHECK: error: expected basic block in uselistorder_bb
-define i32 @foo(i32 %arg) {
- ret i32 %arg
-}
-uselistorder_bb @foo, %arg, { 1, 0 }
diff --git a/llvm/test/Assembler/invalid-uselistorder_bb-not-func.ll b/llvm/test/Assembler/invalid-uselistorder_bb-not-func.ll
deleted file mode 100644
index 080ddc1990e08..0000000000000
--- a/llvm/test/Assembler/invalid-uselistorder_bb-not-func.ll
+++ /dev/null
@@ -1,4 +0,0 @@
-; RUN: not llvm-as < %s -disable-output 2>&1 | FileCheck %s
-; CHECK: error: expected function name in uselistorder_bb
-@global = global i1 0
-uselistorder_bb @global, %bb, { 1, 0 }
diff --git a/llvm/test/Assembler/invalid-uselistorder_bb-numbered.ll b/llvm/test/Assembler/invalid-uselistorder_bb-numbered.ll
deleted file mode 100644
index 92e5b3c876d12..0000000000000
--- a/llvm/test/Assembler/invalid-uselistorder_bb-numbered.ll
+++ /dev/null
@@ -1,11 +0,0 @@
-; RUN: not llvm-as < %s -disable-output 2>&1 | FileCheck %s
-; CHECK: error: invalid numeric label in uselistorder_bb
-
-@ba1 = constant ptr blockaddress (@foo, %1)
-
-define void @foo() {
- br label %1
- unreachable
-}
-
-uselistorder_bb @foo, %1, { 1, 0 }
diff --git a/llvm/test/Assembler/uselistorder_bb.ll b/llvm/test/Assembler/uselistorder_bb.ll
deleted file mode 100644
index 046202f9bee3b..0000000000000
--- a/llvm/test/Assembler/uselistorder_bb.ll
+++ /dev/null
@@ -1,42 +0,0 @@
-; RUN: llvm-as < %s -disable-output 2>&1 | FileCheck %s -allow-empty
-; CHECK-NOT: error
-; CHECK-NOT: warning
-; RUN: verify-uselistorder < %s
-
-@ba1 = constant ptr blockaddress (@bafunc1, %bb)
-@ba2 = constant ptr getelementptr (i8, ptr blockaddress (@bafunc2, %bb), i61 0)
-@ba3 = constant ptr getelementptr (i8, ptr blockaddress (@bafunc2, %bb), i61 0)
-
-define ptr @babefore() {
- ret ptr getelementptr (i8, ptr blockaddress (@bafunc2, %bb), i61 0)
-bb1:
- ret ptr blockaddress (@bafunc1, %bb)
-bb2:
- ret ptr blockaddress (@bafunc3, %bb)
-}
-define void @bafunc1() {
- br label %bb
-bb:
- unreachable
-}
-define void @bafunc2() {
- br label %bb
-bb:
- unreachable
-}
-define void @bafunc3() {
- br label %bb
-bb:
- unreachable
-}
-define ptr @baafter() {
- ret ptr blockaddress (@bafunc2, %bb)
-bb1:
- ret ptr blockaddress (@bafunc1, %bb)
-bb2:
- ret ptr blockaddress (@bafunc3, %bb)
-}
-
-uselistorder_bb @bafunc1, %bb, { 1, 0 }
-uselistorder_bb @bafunc2, %bb, { 1, 0 }
-uselistorder_bb @bafunc3, %bb, { 1, 0 }
diff --git a/llvm/utils/emacs/llvm-mode.el b/llvm/utils/emacs/llvm-mode.el
index e46e1170e48ae..7dc1c28489839 100644
--- a/llvm/utils/emacs/llvm-mode.el
+++ b/llvm/utils/emacs/llvm-mode.el
@@ -74,7 +74,7 @@
`(,(regexp-opt
'(;; Toplevel entities
"declare" "define" "module" "target" "source_filename" "global" "constant" "const" "alias" "ifunc" "comdat"
- "attributes" "uselistorder" "uselistorder_bb"
+ "attributes" "uselistorder"
;; Linkage types
"private" "internal" "weak" "weak_odr" "linkonce" "linkonce_odr" "available_externally" "appending" "common" "extern_weak" "external"
"uninitialized" "implementation" "..."
@@ -120,7 +120,7 @@
;; Fast-math flags
`(,(regexp-opt '("nnan" "ninf" "nsz" "arcp" "contract" "afn" "reassoc" "fast") 'symbols) . font-lock-keyword-face)
;; Use-list order directives
- `(,(regexp-opt '("uselistorder" "uselistorder_bb") 'symbols) . font-lock-keyword-face))
+ `(,(regexp-opt '("uselistorder") 'symbols) . font-lock-keyword-face))
"Syntax highlighting for LLVM.")
(defun llvm-current-defun-name ()
diff --git a/llvm/utils/vim/syntax/llvm.vim b/llvm/utils/vim/syntax/llvm.vim
index d8cf75fa816fc..d921e8bd1e401 100644
--- a/llvm/utils/vim/syntax/llvm.vim
+++ b/llvm/utils/vim/syntax/llvm.vim
@@ -199,7 +199,6 @@ syn keyword llvmKeyword
\ unnamed_addr
\ unordered
\ uselistorder
- \ uselistorder_bb
\ uwtable
\ volatile
\ weak
diff --git a/llvm/utils/vscode/llvm/syntaxes/ll.tmLanguage.yaml b/llvm/utils/vscode/llvm/syntaxes/ll.tmLanguage.yaml
index 0559b8cac5d9d..06d2e43bb3c2e 100644
--- a/llvm/utils/vscode/llvm/syntaxes/ll.tmLanguage.yaml
+++ b/llvm/utils/vscode/llvm/syntaxes/ll.tmLanguage.yaml
@@ -292,7 +292,6 @@ patterns:
\\bunnamed_addr\\b|\
\\bunordered\\b|\
\\buselistorder\\b|\
- \\buselistorder_bb\\b|\
\\buwtable\\b|\
\\bvolatile\\b|\
\\bweak\\b|\
|
nikic
reviewed
Jun 1, 2026
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Makes sense to me. Some time ago I dropped blockaddress from the Function use list, dropping it from the BB use list as well is consistent with that...
Regarding uselistorder_bb, note that we also have USELIST_CODE_BB in bitcode.
Is this actually redundant though? The docs only talk about blockaddress, but isn't the use list order for BBs also relevant because it determines the order of the predecessors iterator?
Created using spr 1.3.8-wip
Contributor
Author
The use list order of a basic block is also be specifiable inside the function with the normal uselistorder directive. This is tested, e.g., by test/Assembler/uselistorder.ll. From what I understand, the uselistorder_bb directive is only required so that it can specify the uselist outside of a function, where a special syntax is needed to identify the block.
This indeed seems to be orthogonal. I do get the impression, though, that uselists aren't particularly well tested and I can't say that I fully understand how our readers/writers work. |
aengelke
deleted the
users/aengelke/spr/ir-blockaddress-doesnt-use-basicblock
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BlockAddress is the only non-terminator user of a BasicBlock, and it
occurs very rarely. To speed up predecessor iteration, change
BlockAddress to no longer use its BasicBlock.
This should also make uselistorder_bb obsolete.