[MLIR][LLVM] Add explicit target_cpu attribute to llvm.func (#78287)

This patch adds the target_cpu attribute to llvm.func MLIR operations
and updates the translation to/from LLVM IR to match "target-cpu"
function attributes.

Author: skatrak

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

@@ -1427,6 +1427,7 @@ def LLVM_LLVMFuncOp : LLVM_Op<"func", [
     OptionalAttr<I64Attr>:$alignment,
     OptionalAttr<LLVM_VScaleRangeAttr>:$vscale_range,
     OptionalAttr<FramePointerKindAttr>:$frame_pointer,
+    OptionalAttr<StrAttr>:$target_cpu,
     OptionalAttr<LLVM_TargetFeaturesAttr>:$target_features
   );
 

mlir/lib/Target/LLVMIR/ModuleImport.cpp

@@ -1744,11 +1744,14 @@ void ModuleImport::processFunctionAttributes(llvm::Function *func,
                                  .value()));
   }
 
+  if (llvm::Attribute attr = func->getFnAttribute("target-cpu");
+      attr.isStringAttribute())
+    funcOp.setTargetCpuAttr(StringAttr::get(context, attr.getValueAsString()));
+
   if (llvm::Attribute attr = func->getFnAttribute("target-features");
-      attr.isStringAttribute()) {
+      attr.isStringAttribute())
     funcOp.setTargetFeaturesAttr(
         LLVM::TargetFeaturesAttr::get(context, attr.getValueAsString()));
-  }
 }
 
 DictionaryAttr

mlir/lib/Target/LLVMIR/ModuleTranslation.cpp

@@ -1104,6 +1104,9 @@ LogicalResult ModuleTranslation::convertOneFunction(LLVMFuncOp func) {
   if (func.getArmPreservesZa())
     llvmFunc->addFnAttr("aarch64_pstate_za_preserved");
 
+  if (auto targetCpu = func.getTargetCpu())
+    llvmFunc->addFnAttr("target-cpu", *targetCpu);
+
   if (auto targetFeatures = func.getTargetFeatures())
     llvmFunc->addFnAttr("target-features", targetFeatures->getFeaturesString());
 

mlir/test/Conversion/FuncToLLVM/convert-funcs.mlir

@@ -61,6 +61,16 @@ func.func @variadic_func(%arg0: i32) attributes { "func.varargs" = true } {
   return
 }
 
+// CHECK-LABEL: llvm.func @target_cpu()
+// CHECK-SAME: target_cpu = "gfx90a"
+func.func private @target_cpu() attributes { "target_cpu" = "gfx90a" }
+
+// CHECK-LABEL: llvm.func @target_features()
+// CHECK-SAME: target_features = #llvm.target_features<["+sme", "+sve"]>
+func.func private @target_features() attributes {
+  "target_features" = #llvm.target_features<["+sme", "+sve"]>
+}
+
 // -----
 
 // CHECK-LABEL: llvm.func @private_callee

mlir/test/Dialect/Bufferization/Transforms/one-shot-module-bufferize-analysis.mlir

@@ -772,7 +772,7 @@ func.func @insert_slice_chain(
 // CHECK-SAME: bufferization.access = "none"
     %arg2: tensor<62x90xf32> {bufferization.buffer_layout = affine_map<(d0, d1) -> (d0, d1)>, bufferization.writable = true})
 // CHECK-SAME: bufferization.access = "write"
-  -> tensor<62x90xf32> attributes {passthrough = [["target-cpu", "skylake-avx512"], ["prefer-vector-width", "512"]]}
+  -> tensor<62x90xf32> attributes {passthrough = [["prefer-vector-width", "512"]], target_cpu = "skylake-avx512"}
 {
   %c0 = arith.constant 0 : index
   %cst = arith.constant 0.000000e+00 : f32

mlir/test/Target/LLVMIR/Import/target-cpu.ll

@@ -0,0 +1,9 @@
+; RUN: mlir-translate -import-llvm -split-input-file %s | FileCheck %s
+
+; CHECK-LABEL: llvm.func @target_cpu()
+; CHECK-SAME: target_cpu = "gfx90a"
+define void @target_cpu() #0 {
+  ret void
+}
+
+attributes #0 = { "target-cpu"="gfx90a" }

mlir/test/Target/LLVMIR/target-cpu.mlir

@@ -0,0 +1,7 @@
+// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s
+
+// CHECK: define void @target_cpu() #[[ATTRS:.*]] {
+// CHECK: attributes #[[ATTRS]] = { "target-cpu"="gfx90a" }
+llvm.func @target_cpu() attributes {target_cpu = "gfx90a"} {
+  llvm.return
+}