[CIR][CIRGen] Add uwtable attribute

The module-level uwtable attribute controls the unwind tables for any synthesized functions, and the function-level attribute controls them for those functions. I'll add support for this attribute to the LLVM dialect as well, but translate it from CIR directly for now to avoid waiting on the MLIR addition and a subsequent rebase.
llvm · Dec 11, 2024 · b31c62e · b31c62e
1 parent 9a63c50
commit b31c62e
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Showing 6 changed files with 118 additions and 2 deletions.
diff --git a/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td b/clang/include/clang/CIR/Dialect/IR/CIRAttrs.td
@@ -1119,6 +1119,35 @@ def ConvergentAttr : CIRUnitAttr<"Convergent", "convergent"> {
   let storageType = [{ ConvergentAttr }];
 }
 
+def UWTableKindNone
+    : I32EnumAttrCase<"None", 0, "none">;
+def UWTableKindSync
+    : I32EnumAttrCase<"Sync", 1, "sync">;
+def UWTableKindAsync
+    : I32EnumAttrCase<"Async", 2, "async">;
+
+def UWTableKind : I32EnumAttr<"UWTableKind", "Unwind table kind", [
+  UWTableKindNone, UWTableKindSync, UWTableKindAsync
+]> {
+  let cppNamespace = "::cir";
+  let genSpecializedAttr = 0;
+}
+
+def UWTableAttr : EnumAttr<CIR_Dialect, UWTableKind, "uwtable"> {
+  let summary = "Unwind table kind attribute";
+  let description = [{
+    The kind of unwind tables to generate for a function. `none` means no unwind
+    tables are generated; `sync` means synchronous unwind tables (that are only
+    valid at call boundaries), and `async` means asynchronous unwind tables
+    (that are valid at all instructions). When applied to a module, this
+    controls the unwind table generation for any synthesized functions.
+  }];
+
+  let assemblyFormat = [{
+    `<` $value `>`
+  }];
+}
+
 class CIR_GlobalCtorDtor<string name, string attrMnemonic,
                          string sum, string desc>
     : CIR_Attr<"Global" # name, "global_" # attrMnemonic> {

diff --git a/clang/include/clang/CIR/Dialect/IR/CIRDialect.td b/clang/include/clang/CIR/Dialect/IR/CIRDialect.td
@@ -38,6 +38,7 @@ def CIR_Dialect : Dialect {
     static llvm::StringRef getLangAttrName() { return "cir.lang"; }
     static llvm::StringRef getTripleAttrName() { return "cir.triple"; }
     static llvm::StringRef getOptInfoAttrName() { return "cir.opt_info"; }
+    static llvm::StringRef getUWTableAttrName() { return "cir.uwtable"; }
 
     static llvm::StringRef getGlobalCtorsAttrName() { return "cir.global_ctors"; }
     static llvm::StringRef getGlobalDtorsAttrName() { return "cir.global_dtors"; }

diff --git a/clang/include/clang/CIR/MissingFeatures.h b/clang/include/clang/CIR/MissingFeatures.h
@@ -369,7 +369,6 @@ struct MissingFeatures {
   static bool codeModel() { return false; }
   static bool largeDataThreshold() { return false; }
   static bool directAccessExternalData() { return false; }
-  static bool setUwtable() { return false; }
   static bool setFramePointer() { return false; }
   static bool simplifyPersonality() { return false; }
   static bool emitVersionIdentMetadata() { return false; }

diff --git a/clang/lib/CIR/CodeGen/CIRGenModule.cpp b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
@@ -2500,6 +2500,12 @@ void CIRGenModule::setCIRFunctionAttributesForDefinition(const Decl *decl,
                                                          FuncOp f) {
   mlir::NamedAttrList attrs{f.getExtraAttrs().getElements().getValue()};
 
+  if ((!decl || !decl->hasAttr<NoUwtableAttr>()) && codeGenOpts.UnwindTables) {
+    auto attr = cir::UWTableKindAttr::get(
+        &getMLIRContext(), cir::UWTableKind(codeGenOpts.UnwindTables));
+    attrs.set(attr.getMnemonic(), attr);
+  }
+
   if (!hasUnwindExceptions(getLangOpts())) {
     auto attr = cir::NoThrowAttr::get(&getMLIRContext());
     attrs.set(attr.getMnemonic(), attr);
@@ -3258,7 +3264,10 @@ void CIRGenModule::Release() {
     llvm_unreachable("NYI");
   assert(!MissingFeatures::directAccessExternalData());
   if (codeGenOpts.UnwindTables)
-    assert(!MissingFeatures::setUwtable());
+    theModule->setAttr(
+        cir::CIRDialect::getUWTableAttrName(),
+        cir::UWTableKindAttr::get(&getMLIRContext(),
+                                  cir::UWTableKind(codeGenOpts.UnwindTables)));
 
   switch (codeGenOpts.getFramePointer()) {
   case CodeGenOptions::FramePointerKind::None:

diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVMIR.cpp b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVMIR.cpp
@@ -81,6 +81,10 @@ class CIRDialectLLVMIRTranslationInterface
       oclVerMD->addOperand(llvm::MDNode::get(llvmContext, oclVerElts));
     }
 
+    if (auto uwTableAttr =
+            mlir::dyn_cast<cir::UWTableKindAttr>(attribute.getValue()))
+      llvmModule->setUwtable(convertUWTableKind(uwTableAttr.getValue()));
+
     // Drop ammended CIR attribute from LLVM op.
     module->removeAttr(attribute.getName());
   }
@@ -129,6 +133,11 @@ class CIRDialectLLVMIRTranslationInterface
                            attr.getValue())) {
           emitOpenCLKernelArgMetadata(clArgMetadata, func.getNumArguments(),
                                       llvmFunc, moduleTranslation);
+        } else if (auto uwTableAttr =
+                       mlir::dyn_cast<cir::UWTableKindAttr>(attr.getValue())) {
+          llvm::AttrBuilder builder(llvmFunc->getContext());
+          builder.addUWTableAttr(convertUWTableKind(uwTableAttr.getValue()));
+          llvmFunc->addFnAttrs(builder);
         }
       }
     }
@@ -261,6 +270,19 @@ class CIRDialectLLVMIRTranslationInterface
       llvmFunc->setMetadata("kernel_arg_name",
                             llvm::MDNode::get(vmCtx, argNames));
   }
+
+private:
+  static llvm::UWTableKind convertUWTableKind(cir::UWTableKind kind) {
+    // TODO(cir): Use UWTableKindAttr from the LLVM dialect when available.
+    switch (kind) {
+    case cir::UWTableKind::None:
+      return llvm::UWTableKind::None;
+    case cir::UWTableKind::Sync:
+      return llvm::UWTableKind::Sync;
+    case cir::UWTableKind::Async:
+      return llvm::UWTableKind::Async;
+    }
+  }
 };
 
 void registerCIRDialectTranslation(mlir::DialectRegistry &registry) {

diff --git a/clang/test/CIR/CodeGen/uwtable.cpp b/clang/test/CIR/CodeGen/uwtable.cpp
@@ -0,0 +1,56 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t-none.cir
+// RUN: FileCheck %s --input-file=%t-none.cir --check-prefix=CIR-NONE
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir -funwind-tables=0 %s -o %t-none-explicit.cir
+// RUN: FileCheck %s --input-file=%t-none-explicit.cir --check-prefix=CIR-NONE
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir -funwind-tables=1 %s -o %t-sync.cir
+// RUN: FileCheck %s --input-file=%t-sync.cir --check-prefix=CIR-SYNC
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir -funwind-tables=2 %s -o %t-async.cir
+// RUN: FileCheck %s --input-file=%t-async.cir --check-prefix=CIR-ASYNC
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o %t-none.ll
+// RUN: FileCheck %s --input-file=%t-none.ll --check-prefix=LLVM-NONE
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm -funwind-tables=0 %s -o %t-none-explicit.ll
+// RUN: FileCheck %s --input-file=%t-none-explicit.ll --check-prefix=LLVM-NONE
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm -funwind-tables=1 %s -o %t-sync.ll
+// RUN: FileCheck %s --input-file=%t-sync.ll --check-prefix=LLVM-SYNC
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm -funwind-tables=2 %s -o %t-async.ll
+// RUN: FileCheck %s --input-file=%t-async.ll --check-prefix=LLVM-ASYNC
+
+// CIR-NONE-NOT: #cir.uwtable
+
+// CIR-SYNC-DAG: module {{.*}} attributes {{{.*}}cir.uwtable = #cir.uwtable<sync>
+// CIR-SYNC-DAG:   cir.func @_Z1fv() extra(#[[f_attr:.*]])
+// CIR-SYNC-DAG:   cir.func @_Z1gv() extra(#[[g_attr:.*]])
+// CIR-SYNC-DAG: #[[f_attr]] = #cir<extra({{{.*}}uwtable = #cir.uwtable<sync>
+// CIR-SYNC-DAG: #[[g_attr]] =
+// CIR-SYNC-NOT:   #cir.uwtable
+
+// CIR-ASYNC-DAG: module {{.*}} attributes {{{.*}}cir.uwtable = #cir.uwtable<async>
+// CIR-ASYNC-DAG:   cir.func @_Z1fv() extra(#[[f_attr:.*]])
+// CIR-ASYNC-DAG:   cir.func @_Z1gv() extra(#[[g_attr:.*]])
+// CIR-ASYNC-DAG: #[[f_attr]] = #cir<extra({{{.*}}uwtable = #cir.uwtable<async>
+// CIR-ASYNC-DAG: #[[g_attr]] =
+// CIR-ASYNC-NOT:   #cir.uwtable
+
+// Avoid matching "uwtable" in the ModuleID and source_filename comments.
+// LLVM-NONE:     define {{.*}} @_Z1fv()
+// LLVM-NONE-NOT: uwtable
+
+// LLVM-SYNC:     define {{.*}} @_Z1fv() #[[#F_ATTRS:]]
+// LLVM-SYNC:     define {{.*}} @_Z1gv() #[[#G_ATTRS:]]
+// LLVM-SYNC:     attributes #[[#F_ATTRS]] = {{{.*}}uwtable(sync)
+// LLVM-SYNC:     attributes #[[#G_ATTRS]] =
+// LLVM-SYNC-NOT:   uwtable
+// LLVM-SYNC-DAG: ![[#METADATA:]] = !{i32 7, !"uwtable", i32 1}
+// LLVM-SYNC-DAG: !llvm.module.flags = !{{{.*}}[[#METADATA]]
+
+// LLVM-ASYNC:     define {{.*}} @_Z1fv() #[[#ATTRS:]]
+// LLVM-ASYNC:     define {{.*}} @_Z1gv() #[[#G_ATTRS:]]
+// LLVM-ASYNC:     attributes #[[#ATTRS]] = {{{.*}}uwtable{{ }}
+// LLVM-ASYNC:     attributes #[[#G_ATTRS]] =
+// LLVM-ASYNC-NOT:   uwtable
+// LLVM-ASYNC-DAG: ![[#METADATA:]] = !{i32 7, !"uwtable", i32 2}
+// LLVM-ASYNC-DAG: !llvm.module.flags = !{{{.*}}[[#METADATA]]
+void f() {}
+
+[[clang::nouwtable]] void g() {}