[Mlir-commits] [llvm] [mlir] [MLIR] Add passthrough attribute to mlir.global (PR #154706)
llvmlistbot at llvm.org
llvmlistbot at llvm.org
Fri Aug 22 01:53:16 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-mlir-llvm
@llvm/pr-subscribers-llvm-ir
Author: Vadim Curcă (VadimCurca)
<details>
<summary>Changes</summary>
Adds a `passthrough` optional array attribute to `mlir.global`, as well as conversions to and from LLVM attributes on `llvm::GlobalVariable` objects. This is necessary to preserve unknown attributes on global variables when converting to and from the LLVM Dialect. Previously, any attributes on an `llvm::GlobalVariable` not explicitly modeled by `mlir.global` were dropped during conversion.
---
Patch is 24.79 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/154706.diff
10 Files Affected:
- (modified) llvm/include/llvm/IR/Attributes.h (+5)
- (modified) llvm/include/llvm/IR/GlobalVariable.h (+5)
- (modified) llvm/lib/IR/Attributes.cpp (+6)
- (modified) mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td (+2-1)
- (modified) mlir/lib/Target/LLVMIR/ModuleImport.cpp (+73-53)
- (modified) mlir/lib/Target/LLVMIR/ModuleTranslation.cpp (+96-78)
- (modified) mlir/test/Target/LLVMIR/Import/function-attributes.ll (+5)
- (modified) mlir/test/Target/LLVMIR/Import/global-variables.ll (+24-12)
- (modified) mlir/test/Target/LLVMIR/llvmir-invalid.mlir (+20)
- (modified) mlir/test/Target/LLVMIR/llvmir.mlir (+12)
``````````diff
diff --git a/llvm/include/llvm/IR/Attributes.h b/llvm/include/llvm/IR/Attributes.h
index 2b500ed58d0d6..9f01c76e6be48 100644
--- a/llvm/include/llvm/IR/Attributes.h
+++ b/llvm/include/llvm/IR/Attributes.h
@@ -384,6 +384,11 @@ class AttributeSet {
bool operator==(const AttributeSet &O) const { return SetNode == O.SetNode; }
bool operator!=(const AttributeSet &O) const { return !(*this == O); }
+ /// Add an attribute to the attribute set. Returns a new set because attribute
+ /// sets are immutable.
+ [[nodiscard]] AttributeSet LLVM_ABI addAttribute(LLVMContext &C,
+ Attribute A) const;
+
/// Add an argument attribute. Returns a new set because attribute sets are
/// immutable.
[[nodiscard]] LLVM_ABI AttributeSet
diff --git a/llvm/include/llvm/IR/GlobalVariable.h b/llvm/include/llvm/IR/GlobalVariable.h
index 388e1d7cfa808..3acd60e397225 100644
--- a/llvm/include/llvm/IR/GlobalVariable.h
+++ b/llvm/include/llvm/IR/GlobalVariable.h
@@ -209,6 +209,11 @@ class GlobalVariable : public GlobalObject, public ilist_node<GlobalVariable> {
LLVM_ABI void
getDebugInfo(SmallVectorImpl<DIGlobalVariableExpression *> &GVs) const;
+ /// Add attribute to this global.
+ void addAttribute(Attribute Attr) {
+ Attrs = Attrs.addAttribute(getContext(), Attr);
+ }
+
/// Add attribute to this global.
void addAttribute(Attribute::AttrKind Kind) {
Attrs = Attrs.addAttribute(getContext(), Kind);
diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index d1fbcb9e893a7..6ee78e1cab365 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -934,6 +934,12 @@ AttributeSet AttributeSet::addAttribute(LLVMContext &C,
return addAttributes(C, AttributeSet::get(C, B));
}
+AttributeSet AttributeSet::addAttribute(LLVMContext &C, Attribute A) const {
+ AttrBuilder B(C);
+ B.addAttribute(A);
+ return addAttributes(C, AttributeSet::get(C, B));
+}
+
AttributeSet AttributeSet::addAttribute(LLVMContext &C, StringRef Kind,
StringRef Value) const {
AttrBuilder B(C);
diff --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
index 3f27f6d9ae8b7..8ebc2d0cbea77 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
@@ -1313,7 +1313,8 @@ def LLVM_GlobalOp : LLVM_Op<"mlir.global",
OptionalAttr<StrAttr>:$section,
OptionalAttr<SymbolRefAttr>:$comdat,
OptionalAttr<DIGlobalVariableExpressionArrayAttr>:$dbg_exprs,
- DefaultValuedAttr<Visibility, "mlir::LLVM::Visibility::Default">:$visibility_
+ DefaultValuedAttr<Visibility, "mlir::LLVM::Visibility::Default">:$visibility_,
+ OptionalAttr<ArrayAttr>:$passthrough
);
let summary = "LLVM dialect global.";
let description = [{
diff --git a/mlir/lib/Target/LLVMIR/ModuleImport.cpp b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
index a207cceef88b5..12275fb6a3abf 100644
--- a/mlir/lib/Target/LLVMIR/ModuleImport.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleImport.cpp
@@ -1395,6 +1395,67 @@ LogicalResult ModuleImport::convertIFunc(llvm::GlobalIFunc *ifunc) {
return success();
}
+/// Converts LLVM string, integer, and enum attributes into MLIR attributes,
+/// skipping those in `attributesToSkip` and emitting a warning at `loc` for
+/// any other unsupported attributes.
+static ArrayAttr
+processPassthroughAttrs(Location loc, MLIRContext *context,
+ llvm::AttributeSet attributes,
+ ArrayRef<StringLiteral> attributesToSkip = {}) {
+ SmallVector<Attribute> passthroughs;
+ for (llvm::Attribute attr : attributes) {
+ StringRef attrName;
+ if (attr.isStringAttribute())
+ attrName = attr.getKindAsString();
+ else
+ attrName = llvm::Attribute::getNameFromAttrKind(attr.getKindAsEnum());
+ if (llvm::is_contained(attributesToSkip, attrName))
+ continue;
+
+ auto keyAttr = StringAttr::get(context, attrName);
+ if (attr.isStringAttribute()) {
+ StringRef val = attr.getValueAsString();
+ if (val.empty()) {
+ // For string attributes without values, add only the attribute name.
+ passthroughs.push_back(keyAttr);
+ continue;
+ }
+ // For string attributes with a value, create a [name, value] pair.
+ passthroughs.push_back(
+ ArrayAttr::get(context, {keyAttr, StringAttr::get(context, val)}));
+ continue;
+ }
+ if (attr.isIntAttribute()) {
+ // For integer attributes, convert the value to a string and create a
+ // [name, value] pair.
+ auto val = std::to_string(attr.getValueAsInt());
+ passthroughs.push_back(
+ ArrayAttr::get(context, {keyAttr, StringAttr::get(context, val)}));
+ continue;
+ }
+ if (attr.isEnumAttribute()) {
+ // For enum attributes, add only the attribute name.
+ passthroughs.push_back(keyAttr);
+ continue;
+ }
+
+ emitWarning(loc)
+ << "'" << attrName
+ << "' attribute is invalid on current operation, skipping it";
+ }
+ return ArrayAttr::get(context, passthroughs);
+}
+
+/// Converts LLVM attributes from `globalVar` into MLIR attributes and adds them
+/// to `globalOp` as passthrough attributes.
+static void processPassthroughAttrs(llvm::GlobalVariable *globalVar,
+ GlobalOp globalOp) {
+ ArrayAttr passthroughAttr = processPassthroughAttrs(
+ globalOp.getLoc(), globalOp.getContext(), globalVar->getAttributes());
+ if (!passthroughAttr.empty())
+ globalOp.setPassthroughAttr(passthroughAttr);
+}
+
LogicalResult ModuleImport::convertGlobal(llvm::GlobalVariable *globalVar) {
// Insert the global after the last one or at the start of the module.
OpBuilder::InsertionGuard guard = setGlobalInsertionPoint();
@@ -1460,6 +1521,8 @@ LogicalResult ModuleImport::convertGlobal(llvm::GlobalVariable *globalVar) {
if (globalVar->hasComdat())
globalOp.setComdatAttr(comdatMapping.lookup(globalVar->getComdat()));
+ processPassthroughAttrs(globalVar, globalOp);
+
return success();
}
@@ -2512,7 +2575,7 @@ static void processMemoryEffects(llvm::Function *func, LLVMFuncOp funcOp) {
// List of LLVM IR attributes that map to an explicit attribute on the MLIR
// LLVMFuncOp.
-static constexpr std::array kExplicitAttributes{
+static constexpr std::array kExplicitLLVMFuncOpAttributes{
StringLiteral("aarch64_in_za"),
StringLiteral("aarch64_inout_za"),
StringLiteral("aarch64_new_za"),
@@ -2542,63 +2605,20 @@ static constexpr std::array kExplicitAttributes{
StringLiteral("uwtable"),
StringLiteral("vscale_range"),
StringLiteral("willreturn"),
+ StringLiteral("memory"),
};
+/// Converts LLVM attributes from `func` into MLIR attributes and adds them
+/// to `funcOp` as passthrough attributes, skipping those listed in
+/// `kExplicitLLVMFuncAttributes`.
static void processPassthroughAttrs(llvm::Function *func, LLVMFuncOp funcOp) {
- MLIRContext *context = funcOp.getContext();
- SmallVector<Attribute> passthroughs;
llvm::AttributeSet funcAttrs = func->getAttributes().getAttributes(
llvm::AttributeList::AttrIndex::FunctionIndex);
- for (llvm::Attribute attr : funcAttrs) {
- // Skip the memory attribute since the LLVMFuncOp has an explicit memory
- // attribute.
- if (attr.hasAttribute(llvm::Attribute::Memory))
- continue;
-
- // Skip invalid type attributes.
- if (attr.isTypeAttribute()) {
- emitWarning(funcOp.getLoc(),
- "type attributes on a function are invalid, skipping it");
- continue;
- }
-
- StringRef attrName;
- if (attr.isStringAttribute())
- attrName = attr.getKindAsString();
- else
- attrName = llvm::Attribute::getNameFromAttrKind(attr.getKindAsEnum());
- auto keyAttr = StringAttr::get(context, attrName);
-
- // Skip attributes that map to an explicit attribute on the LLVMFuncOp.
- if (llvm::is_contained(kExplicitAttributes, attrName))
- continue;
-
- if (attr.isStringAttribute()) {
- StringRef val = attr.getValueAsString();
- if (val.empty()) {
- passthroughs.push_back(keyAttr);
- continue;
- }
- passthroughs.push_back(
- ArrayAttr::get(context, {keyAttr, StringAttr::get(context, val)}));
- continue;
- }
- if (attr.isIntAttribute()) {
- auto val = std::to_string(attr.getValueAsInt());
- passthroughs.push_back(
- ArrayAttr::get(context, {keyAttr, StringAttr::get(context, val)}));
- continue;
- }
- if (attr.isEnumAttribute()) {
- passthroughs.push_back(keyAttr);
- continue;
- }
-
- llvm_unreachable("unexpected attribute kind");
- }
-
- if (!passthroughs.empty())
- funcOp.setPassthroughAttr(ArrayAttr::get(context, passthroughs));
+ ArrayAttr passthroughAttr =
+ processPassthroughAttrs(funcOp.getLoc(), funcOp.getContext(), funcAttrs,
+ kExplicitLLVMFuncOpAttributes);
+ if (!passthroughAttr.empty())
+ funcOp.setPassthroughAttr(passthroughAttr);
}
void ModuleImport::processFunctionAttributes(llvm::Function *func,
diff --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index 2685b5c91426e..e277d85596413 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -1081,6 +1081,89 @@ static void addRuntimePreemptionSpecifier(bool dsoLocalRequested,
gv->setDSOLocal(true);
}
+/// Attempts to add an attribute identified by `key`, optionally with the given
+/// `value`, using `addAttribute` function. Reports errors at `loc` if any. If
+/// the attribute has a kind known to LLVM IR, create the attribute of this
+/// kind, otherwise keep it as a string attribute. Performs additional checks
+/// for attributes known to have or not have a value in order to avoid
+/// assertions inside LLVM upon construction. Expects `addAttribute` callable to
+/// forward its arguments to a method that adds an attribute to an object.
+template <typename AddAttributeFn>
+static LogicalResult checkedAddAttribute(Location loc, llvm::LLVMContext &ctx,
+ AddAttributeFn &&addAttribute,
+ StringRef key,
+ StringRef value = StringRef()) {
+ auto kind = llvm::Attribute::getAttrKindFromName(key);
+ if (kind == llvm::Attribute::None) {
+ addAttribute(key, value);
+ return success();
+ }
+
+ if (llvm::Attribute::isIntAttrKind(kind)) {
+ if (value.empty())
+ return emitError(loc) << "LLVM attribute '" << key << "' expects a value";
+
+ int64_t result;
+ if (!value.getAsInteger(/*Radix=*/0, result))
+ addAttribute(llvm::Attribute::get(ctx, kind, result));
+ else
+ addAttribute(key, value);
+ return success();
+ }
+
+ if (!value.empty())
+ return emitError(loc) << "LLVM attribute '" << key
+ << "' does not expect a value, found '" << value
+ << "'";
+
+ addAttribute(kind);
+ return success();
+}
+
+/// Adds the attributes listed in the given array attribute using `addAttribute`
+/// callable. Reports error to `loc` if any and returns immediately. Expects
+/// `attributes` to be an array attribute containing either string attributes,
+/// treated as value-less LLVM attributes, or array attributes containing two
+/// string attributes, with the first string being the name of the corresponding
+/// LLVM attribute and the second string beings its value. Note that even
+/// integer attributes are expected to have their values expressed as strings.
+/// Expects `addAttribute` callable to forward its arguments to a method that
+/// adds an attribute to an object.
+template <typename AddAttributeFn>
+static LogicalResult
+forwardPassthroughAttributes(Location loc, llvm::LLVMContext &ctx,
+ std::optional<ArrayAttr> attributes,
+ AddAttributeFn &&addAttribute) {
+ if (!attributes)
+ return success();
+
+ for (Attribute attr : *attributes) {
+ if (auto stringAttr = dyn_cast<StringAttr>(attr)) {
+ if (failed(checkedAddAttribute(loc, ctx, addAttribute,
+ stringAttr.getValue())))
+ return failure();
+ continue;
+ }
+
+ auto arrayAttr = dyn_cast<ArrayAttr>(attr);
+ if (!arrayAttr || arrayAttr.size() != 2)
+ return emitError(loc) << "expected 'passthrough' to contain string "
+ "or array attributes";
+
+ auto keyAttr = dyn_cast<StringAttr>(arrayAttr[0]);
+ auto valueAttr = dyn_cast<StringAttr>(arrayAttr[1]);
+ if (!keyAttr || !valueAttr)
+ return emitError(loc) << "expected arrays within 'passthrough' to "
+ "contain two strings";
+
+ if (failed(checkedAddAttribute(loc, ctx, addAttribute, keyAttr.getValue(),
+ valueAttr.getValue())))
+ return failure();
+ }
+
+ return success();
+}
+
LogicalResult ModuleTranslation::convertGlobalsAndAliases() {
// Mapping from compile unit to its respective set of global variables.
DenseMap<llvm::DICompileUnit *, SmallVector<llvm::Metadata *>> allGVars;
@@ -1191,6 +1274,14 @@ LogicalResult ModuleTranslation::convertGlobalsAndAliases() {
}
}
}
+
+ // Forward the pass-through attributes to LLVM.
+ auto addAttribute = [var](auto &&...args) {
+ var->addAttribute(std::forward<decltype(args)>(args)...);
+ };
+ if (failed(forwardPassthroughAttributes(op.getLoc(), var->getContext(),
+ op.getPassthrough(), addAttribute)))
+ return failure();
}
// Create all llvm::GlobalAlias
@@ -1381,44 +1472,6 @@ LogicalResult ModuleTranslation::convertGlobalsAndAliases() {
return success();
}
-/// Attempts to add an attribute identified by `key`, optionally with the given
-/// `value` to LLVM function `llvmFunc`. Reports errors at `loc` if any. If the
-/// attribute has a kind known to LLVM IR, create the attribute of this kind,
-/// otherwise keep it as a string attribute. Performs additional checks for
-/// attributes known to have or not have a value in order to avoid assertions
-/// inside LLVM upon construction.
-static LogicalResult checkedAddLLVMFnAttribute(Location loc,
- llvm::Function *llvmFunc,
- StringRef key,
- StringRef value = StringRef()) {
- auto kind = llvm::Attribute::getAttrKindFromName(key);
- if (kind == llvm::Attribute::None) {
- llvmFunc->addFnAttr(key, value);
- return success();
- }
-
- if (llvm::Attribute::isIntAttrKind(kind)) {
- if (value.empty())
- return emitError(loc) << "LLVM attribute '" << key << "' expects a value";
-
- int64_t result;
- if (!value.getAsInteger(/*Radix=*/0, result))
- llvmFunc->addFnAttr(
- llvm::Attribute::get(llvmFunc->getContext(), kind, result));
- else
- llvmFunc->addFnAttr(key, value);
- return success();
- }
-
- if (!value.empty())
- return emitError(loc) << "LLVM attribute '" << key
- << "' does not expect a value, found '" << value
- << "'";
-
- llvmFunc->addFnAttr(kind);
- return success();
-}
-
/// Return a representation of `value` as metadata.
static llvm::Metadata *convertIntegerToMetadata(llvm::LLVMContext &context,
const llvm::APInt &value) {
@@ -1454,45 +1507,6 @@ static llvm::MDNode *convertIntegerArrayToMDNode(llvm::LLVMContext &context,
return llvm::MDNode::get(context, mdValues);
}
-/// Attaches the attributes listed in the given array attribute to `llvmFunc`.
-/// Reports error to `loc` if any and returns immediately. Expects `attributes`
-/// to be an array attribute containing either string attributes, treated as
-/// value-less LLVM attributes, or array attributes containing two string
-/// attributes, with the first string being the name of the corresponding LLVM
-/// attribute and the second string beings its value. Note that even integer
-/// attributes are expected to have their values expressed as strings.
-static LogicalResult
-forwardPassthroughAttributes(Location loc, std::optional<ArrayAttr> attributes,
- llvm::Function *llvmFunc) {
- if (!attributes)
- return success();
-
- for (Attribute attr : *attributes) {
- if (auto stringAttr = dyn_cast<StringAttr>(attr)) {
- if (failed(
- checkedAddLLVMFnAttribute(loc, llvmFunc, stringAttr.getValue())))
- return failure();
- continue;
- }
-
- auto arrayAttr = dyn_cast<ArrayAttr>(attr);
- if (!arrayAttr || arrayAttr.size() != 2)
- return emitError(loc)
- << "expected 'passthrough' to contain string or array attributes";
-
- auto keyAttr = dyn_cast<StringAttr>(arrayAttr[0]);
- auto valueAttr = dyn_cast<StringAttr>(arrayAttr[1]);
- if (!keyAttr || !valueAttr)
- return emitError(loc)
- << "expected arrays within 'passthrough' to contain two strings";
-
- if (failed(checkedAddLLVMFnAttribute(loc, llvmFunc, keyAttr.getValue(),
- valueAttr.getValue())))
- return failure();
- }
- return success();
-}
-
LogicalResult ModuleTranslation::convertOneFunction(LLVMFuncOp func) {
// Clear the block, branch value mappings, they are only relevant within one
// function.
@@ -1864,8 +1878,12 @@ LogicalResult ModuleTranslation::convertFunctionSignatures() {
}
// Forward the pass-through attributes to LLVM.
+ auto addAttribute = [llvmFunc](auto &&...args) {
+ llvmFunc->addFnAttr(std::forward<decltype(args)>(args)...);
+ };
if (failed(forwardPassthroughAttributes(
- function.getLoc(), function.getPassthrough(), llvmFunc)))
+ function.getLoc(), llvmFunc->getContext(),
+ function.getPassthrough(), addAttribute)))
return failure();
// Convert visibility attribute.
diff --git a/mlir/test/Target/LLVMIR/Import/function-attributes.ll b/mlir/test/Target/LLVMIR/Import/function-attributes.ll
index 0b13645853cea..683a0c48d7377 100644
--- a/mlir/test/Target/LLVMIR/Import/function-attributes.ll
+++ b/mlir/test/Target/LLVMIR/Import/function-attributes.ll
@@ -426,3 +426,8 @@ declare void @nounwind_attribute() nounwind
; CHECK-LABEL: @willreturn_attribute
; CHECK-SAME: attributes {will_return}
declare void @willreturn_attribute() willreturn
+
+// -----
+
+; expected-warning @unknown {{'preallocated' attribute is invalid on current operation, skipping it}}
+declare void @test() preallocated(i32)
diff --git a/mlir/test/Target/LLVMIR/Import/global-variables.ll b/mlir/test/Target/LLVMIR/Import/global-variables.ll
index b8bbdbab2e2ca..df75b1faa19be 100644
--- a/mlir/test/Target/LLVMIR/Import/global-variables.ll
+++ b/mlir/test/Target/LLVMIR/Import/global-variables.ll
@@ -186,19 +186,16 @@
; CHECK-SAME: {addr_space = 0 : i32, dso_local} : !llvm.array<2 x f32>
@array_constant = internal constant [2 x float] [float 1., float 2.]
-; CHECK: llvm.mlir.global internal constant @nested_array_constant
-; CHECK-SAME-LITERAL: (dense<[[1, 2], [3, 4]]> : tensor<2x2xi32>)
-; CHECK-SAME-LITERAL: {addr_space = 0 : i32, dso_local} : !llvm.array<2 x array<2 x i32>>
+; CHECK{LITERAL}: llvm.mlir.global internal constant @nested_array_constant(dense<[[1, 2], [3, 4]]> : tensor<2x2xi32>)
+; CHECK-SAME: {addr_space = 0 : i32, dso_local} : !llvm.array<2 x array<2 x i32>>
@nested_array_constant = internal constant [2 x [2 x i32]] [[2 x i32] [i32 1, i32 2], [2 x i32] [i32 3, i32 4]]
-; CHECK: llvm.mlir.global internal constant @nested_array_constant3
-; CHECK-SAME-LITERAL: (dense<[[[1, 2], [3, 4]]]> : tensor<1x2x2xi32>)
-; CHECK-SAME-LITERAL: {addr_space = 0 : i32, dso_local} : !llvm.array<1 x array<2 x array<2 x i32>>>
+; CHECK{LITERAL}: llvm.mlir.global internal constant @nested_array_constant3(dense<[[[1, 2], [3, 4]]]> : tensor<1x2x2xi32>)
+; CHECK-SAME: {addr_space = 0 : i32, dso_local} : !llvm.array<1 x array<2 x array<2 x i32>>>
@nested_array_constant3 = internal constant [1 x [2 x [2 x i32]]] [[2 x [2 x i32]] [[2 x i32] ...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/154706
More information about the Mlir-commits
mailing list