[MLIR] Add attributes no_unwind and will_return to the LLVMIR dialect (#98921)

And testing.
These are being added to be used in the GPU to LLVM SPV pass.

---------

Co-authored-by: Victor Perez <victor.perez@codeplay.com>

Author: 2 people

mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td

@@ -1461,6 +1461,8 @@ def LLVM_LLVMFuncOp : LLVM_Op<"func", [
     OptionalAttr<StrAttr>:$fp_contract,
     OptionalAttr<UnitAttr>:$no_inline,
     OptionalAttr<UnitAttr>:$always_inline,
+    OptionalAttr<UnitAttr>:$no_unwind,
+    OptionalAttr<UnitAttr>:$will_return,
     OptionalAttr<UnitAttr>:$optimize_none
   );
 

mlir/lib/Target/LLVMIR/ModuleImport.cpp

@@ -1686,11 +1686,13 @@ static constexpr std::array kExplicitAttributes{
     StringLiteral("no-nans-fp-math"),
     StringLiteral("no-signed-zeros-fp-math"),
     StringLiteral("noinline"),
+    StringLiteral("nounwind"),
     StringLiteral("optnone"),
     StringLiteral("target-features"),
     StringLiteral("tune-cpu"),
     StringLiteral("unsafe-fp-math"),
     StringLiteral("vscale_range"),
+    StringLiteral("willreturn"),
 };
 
 static void processPassthroughAttrs(llvm::Function *func, LLVMFuncOp funcOp) {
@@ -1763,6 +1765,10 @@ void ModuleImport::processFunctionAttributes(llvm::Function *func,
     funcOp.setOptimizeNone(true);
   if (func->hasFnAttribute(llvm::Attribute::Convergent))
     funcOp.setConvergent(true);
+  if (func->hasFnAttribute(llvm::Attribute::NoUnwind))
+    funcOp.setNoUnwind(true);
+  if (func->hasFnAttribute(llvm::Attribute::WillReturn))
+    funcOp.setWillReturn(true);
 
   if (func->hasFnAttribute("aarch64_pstate_sm_enabled"))
     funcOp.setArmStreaming(true);

mlir/lib/Target/LLVMIR/ModuleTranslation.cpp

@@ -1441,6 +1441,10 @@ static void convertFunctionAttributes(LLVMFuncOp func,
     llvmFunc->addFnAttr(llvm::Attribute::OptimizeNone);
   if (func.getConvergentAttr())
     llvmFunc->addFnAttr(llvm::Attribute::Convergent);
+  if (func.getNoUnwindAttr())
+    llvmFunc->addFnAttr(llvm::Attribute::NoUnwind);
+  if (func.getWillReturnAttr())
+    llvmFunc->addFnAttr(llvm::Attribute::WillReturn);
   convertFunctionMemoryAttributes(func, llvmFunc);
 }
 

mlir/test/Dialect/LLVMIR/func.mlir

@@ -312,6 +312,19 @@ module {
     llvm.return
   }
 
+  llvm.func @nounwind_function() attributes {no_unwind} {
+    // CHECK: @nounwind_function
+    // CHECK-SAME: attributes {no_unwind}
+    llvm.return
+  }
+
+  llvm.func @willreturn_function() attributes {will_return} {
+    // CHECK: @willreturn_function
+    // CHECK-SAME: attributes {will_return}
+    llvm.return
+  }
+
+
 }
 
 // -----

mlir/test/Target/LLVMIR/Import/function-attributes.ll

@@ -385,3 +385,15 @@ declare void @optnone_attribute() noinline optnone
 ; CHECK-LABEL: @convergent_attribute
 ; CHECK-SAME: attributes {convergent}
 declare void @convergent_attribute() convergent
+
+// -----
+
+; CHECK-LABEL: @nounwind_attribute
+; CHECK-SAME: attributes {no_unwind}
+declare void @nounwind_attribute() nounwind
+
+// -----
+
+; CHECK-LABEL: @willreturn_attribute
+; CHECK-SAME: attributes {will_return}
+declare void @willreturn_attribute() willreturn

mlir/test/Target/LLVMIR/llvmir.mlir

@@ -2452,3 +2452,25 @@ llvm.func @convergent() attributes { convergent } {
 
 // CHECK: #[[ATTRS]]
 // CHECK-SAME: convergent
+
+// -----
+
+// CHECK-LABEL: @nounwind
+// CHECK-SAME: #[[ATTRS:[0-9]+]]
+llvm.func @nounwind() attributes { no_unwind } {
+  llvm.return
+}
+
+// CHECK: #[[ATTRS]]
+// CHECK-SAME: nounwind
+
+// -----
+
+// CHECK-LABEL: @willreturn
+// CHECK-SAME: #[[ATTRS:[0-9]+]]
+llvm.func @willreturn() attributes { will_return } {
+  llvm.return
+}
+
+// CHECK: #[[ATTRS]]
+// CHECK-SAME: willreturn