[LLDB] Add CPU feature check support to Darwin

Add new `CPUFeature` class as an abstraction to
hide the platform-specific implementations to
check for CPU features.

Unify local (on host) and remote (on device) test
execution by always going through
`test.Base.run_platform_command()` which uses
LLDB's `platform shell <cmd>` command.

Author: yln

lldb/packages/Python/lldbsuite/test/cpu_feature.py

@@ -0,0 +1,55 @@
+"""
+Platform-agnostic helper to query for CPU features.
+"""
+
+import re
+
+
+class CPUFeature:
+    def __init__(self, linux_cpu_info_flag: str, darwin_sysctl_key: str):
+        self.cpu_info_flag = linux_cpu_info_flag
+        self.sysctl_key = darwin_sysctl_key
+
+    def is_supported(self, triple, cmd_runner):
+        if re.match(".*-.*-linux", triple):
+            err_msg, res = self._is_supported_linux(cmd_runner)
+        elif re.match(".*-apple-.*", triple):
+            err_msg, res = self._is_supported_darwin(cmd_runner)
+        else:
+            err_msg, res = None, False
+
+        if err_msg:
+            print(f"CPU feature check failed: {err_msg}")
+
+        return res
+
+    def _is_supported_linux(self, cmd_runner):
+        cmd = "cat /proc/cpuinfo"
+        err, retcode, output = cmd_runner(cmd)
+        if err.Fail() or retcode != 0:
+            err_msg = f"cat /proc/cpuinfo failed: {output}"
+            return err_msg, False
+
+        return None, (self.cpu_info_flag in output)
+
+    def _is_supported_darwin(self, cmd_runner):
+        cmd = f"sysctl -n {self.sysctl_key}"
+        err, retcode, output = cmd_runner(cmd)
+        if err.Fail() or retcode != 0:
+            return output, False
+
+        return None, (output.strip() == "1")
+
+
+# List of CPU features
+FPMR = CPUFeature("fpmr", "???")
+GCS = CPUFeature("gcs", "???")
+LASX = CPUFeature("lasx", "???")
+LSX = CPUFeature("lsx", "???")
+MTE = CPUFeature("mte", "???")
+MTE_STORE_ONLY = CPUFeature("mtestoreonly", "???")
+PTR_AUTH = CPUFeature("paca", "hw.optional.arm.FEAT_PAuth2")
+SME = CPUFeature("sme", "hw.optional.arm.FEAT_SME")
+SME_FA64 = CPUFeature("smefa64", "???")
+SME2 = CPUFeature("sme2", "hw.optional.arm.FEAT_SME2")
+SVE = CPUFeature("sve", "???")

lldb/packages/Python/lldbsuite/test/lldbtest.py

@@ -48,6 +48,7 @@
 # LLDB modules
 import lldb
 from . import configuration
+from . import cpu_feature
 from . import decorators
 from . import lldbplatformutil
 from . import lldbtest_config
@@ -1315,39 +1316,6 @@ def isPPC64le(self):
             return True
         return False
 
-    def getCPUInfo(self):
-        triple = self.dbg.GetSelectedPlatform().GetTriple()
-
-        # TODO other platforms, please implement this function
-        if not re.match(".*-.*-linux", triple):
-            return ""
-
-        # Need to do something different for non-Linux/Android targets
-        cpuinfo_path = self.getBuildArtifact("cpuinfo")
-        if configuration.lldb_platform_name:
-            self.runCmd(
-                'platform get-file "/proc/cpuinfo" ' + cpuinfo_path, check=False
-            )
-            if not self.res.Succeeded():
-                if self.TraceOn():
-                    print(
-                        'Failed to get /proc/cpuinfo from remote: "{}"'.format(
-                            self.res.GetOutput().strip()
-                        )
-                    )
-                    print("All cpuinfo feature checks will fail.")
-                return ""
-        else:
-            cpuinfo_path = "/proc/cpuinfo"
-
-        try:
-            with open(cpuinfo_path, "r") as f:
-                cpuinfo = f.read()
-        except:
-            return ""
-
-        return cpuinfo
-
     def isAArch64(self):
         """Returns true if the architecture is AArch64."""
         arch = self.getArchitecture().lower()
@@ -1360,39 +1328,43 @@ def isARM(self):
             self.getArchitecture().lower().startswith("arm")
         )
 
+    def isSupported(self, cpu_feature: cpu_feature.CPUFeature):
+        triple = self.dbg.GetSelectedPlatform().GetTriple()
+        cmd_runner = self.run_platform_command
+        return cpu_feature.is_supported(triple, cmd_runner)
+
     def isAArch64SVE(self):
-        return self.isAArch64() and "sve" in self.getCPUInfo()
+        return self.isAArch64() and self.isSupported(cpu_feature.SVE)
 
     def isAArch64SME(self):
-        return self.isAArch64() and "sme" in self.getCPUInfo()
+        return self.isAArch64() and self.isSupported(cpu_feature.SME)
 
     def isAArch64SME2(self):
         # If you have sme2, you also have sme.
-        return self.isAArch64() and "sme2" in self.getCPUInfo()
+        return self.isAArch64() and self.isSupported(cpu_feature.SME2)
 
     def isAArch64SMEFA64(self):
         # smefa64 allows the use of the full A64 instruction set in streaming
         # mode. This is required by certain test programs to setup register
         # state.
-        cpuinfo = self.getCPUInfo()
-        return self.isAArch64() and "sme" in cpuinfo and "smefa64" in cpuinfo
+        return self.isAArch64() and self.isSupported(cpu_feature.SME) and self.isSupported(cpu_feature.SME_FA64)
 
     def isAArch64MTE(self):
-        return self.isAArch64() and "mte" in self.getCPUInfo()
+        return self.isAArch64() and self.isSupported(cpu_feature.MTE)
 
     def isAArch64MTEStoreOnly(self):
-        return self.isAArch64() and "mtestoreonly" in self.getCPUInfo()
+        return self.isAArch64() and self.isSupported(cpu_feature.MTE_STORE_ONLY)
 
     def isAArch64GCS(self):
-        return self.isAArch64() and "gcs" in self.getCPUInfo()
+        return self.isAArch64() and self.isSupported(cpu_feature.GCS)
 
     def isAArch64PAuth(self):
         if self.getArchitecture() == "arm64e":
             return True
-        return self.isAArch64() and "paca" in self.getCPUInfo()
+        return self.isAArch64() and self.isSupported(cpu_feature.PTR_AUTH)
 
     def isAArch64FPMR(self):
-        return self.isAArch64() and "fpmr" in self.getCPUInfo()
+        return self.isAArch64() and self.isSupported(cpu_feature.FPMR)
 
     def isAArch64Windows(self):
         """Returns true if the architecture is AArch64 and platform windows."""
@@ -1407,10 +1379,10 @@ def isLoongArch(self):
         return arch in ["loongarch64", "loongarch32"]
 
     def isLoongArchLSX(self):
-        return self.isLoongArch() and "lsx" in self.getCPUInfo()
+        return self.isLoongArch() and self.isSupported(cpu_feature.LSX)
 
     def isLoongArchLASX(self):
-        return self.isLoongArch() and "lasx" in self.getCPUInfo()
+        return self.isLoongArch() and self.isSupported(cpu_feature.LASX)
 
     def isRISCV(self):
         """Returns true if the architecture is RISCV64 or RISCV32."""

lldb/test/API/commands/register/register/register_command/TestRegisters.py

@@ -21,24 +21,6 @@ def tearDown(self):
         self.dbg.GetSelectedTarget().GetProcess().Destroy()
         TestBase.tearDown(self)
 
-    # on macOS, detect if the current machine is arm64 and supports SME
-    def get_sme_available(self):
-        if self.getArchitecture() != "arm64":
-            return None
-        try:
-            sysctl_output = subprocess.check_output(
-                ["sysctl", "hw.optional.arm.FEAT_SME"]
-            ).decode("utf-8")
-        except subprocess.CalledProcessError:
-            return None
-        m = re.match(r"hw\.optional\.arm\.FEAT_SME: (\w+)", sysctl_output)
-        if m:
-            if int(m.group(1)) == 1:
-                return True
-            else:
-                return False
-        return None
-
     @skipIfiOSSimulator
     @skipIf(archs=no_match(["amd64", "arm$", "i386", "x86_64"]))
     @expectedFailureAll(oslist=["freebsd", "netbsd"], bugnumber="llvm.org/pr48371")
@@ -51,7 +33,7 @@ def test_register_commands(self):
         self.log_enable("registers")
 
         error_str_matched = False
-        if self.get_sme_available() and self.platformIsDarwin():
+        if self.isAArch64SME() and self.platformIsDarwin():
             # On Darwin AArch64 SME machines, we will have unavailable
             # registers when not in Streaming SVE Mode/SME, so
             # `register read -a` will report that some registers