[mlir][ArmSME] Add enable_arm_streaming_ignore attribute (#66911)

This attribute makes the `enable_arm_streaming` pass ignore a function
(i.e. not add the enable streaming/za attributes). The main use case for
this is to prevent helper functions within tests being made streaming
functions.

Author: MacDue

mlir/lib/Dialect/ArmSME/Transforms/EnableArmStreaming.cpp

@@ -52,6 +52,8 @@ using namespace mlir::arm_sme;
 static constexpr char kArmStreamingAttr[] = "arm_streaming";
 static constexpr char kArmLocallyStreamingAttr[] = "arm_locally_streaming";
 static constexpr char kArmZAAttr[] = "arm_za";
+static constexpr char kEnableArmStreamingIgnoreAttr[] =
+    "enable_arm_streaming_ignore";
 
 namespace {
 struct EnableArmStreamingPass
@@ -61,7 +63,9 @@ struct EnableArmStreamingPass
     this->enableZA = enableZA;
   }
   void runOnOperation() override {
-    std::string attr;
+    if (getOperation()->getAttr(kEnableArmStreamingIgnoreAttr))
+      return;
+    StringRef attr;
     switch (mode) {
     case ArmStreaming::Default:
       attr = kArmStreamingAttr;

mlir/test/Dialect/ArmSME/enable-arm-streaming.mlir

@@ -9,3 +9,11 @@
 // CHECK-ENABLE-ZA-LABEL: @arm_streaming
 // CHECK-ENABLE-ZA-SAME: attributes {arm_streaming, arm_za}
 func.func @arm_streaming() { return }
+
+// CHECK-LABEL: @not_arm_streaming
+// CHECK-SAME: attributes {enable_arm_streaming_ignore}
+// CHECK-LOCALLY-LABEL: @not_arm_streaming
+// CHECK-LOCALLY-SAME: attributes {enable_arm_streaming_ignore}
+// CHECK-ENABLE-ZA-LABEL: @not_arm_streaming
+// CHECK-ENABLE-ZA-SAME: attributes {enable_arm_streaming_ignore}
+func.func @not_arm_streaming() attributes {enable_arm_streaming_ignore} { return }