[Lldb-commits] [lldb] [lldb][test] Make Linux cpuinfo check more robust (PR #160675)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: David Spickett (DavidSpickett)

<details>
<summary>Changes</summary>

We were looking for any mention of the feature name in cpuinfo, which could have hit anything including features with common prefixes like sme, sme2, smefa64.

Luckily this was not a problem but I'm changing this to find the features line and split the features into a list. Then we are only looking for exact matches.

Here's the information for one core as an example:
```
processor	: 7
BogoMIPS	: 200.00
Features	: fp asimd evtstrm crc32 atomics fphp asimdhp cpuid <...>
CPU implementer	: 0x41
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0xd0f
CPU revision	: 0
```
(and to avoid any doubt, this is from a CPU simulated in Arm's FVP, it's not real)

Note that the layout of the label, colon, values is sometimes aligned but not always. So I trim whitespace a few times to normalise that.

This repeats once for each core so we only need to find one features line.

---
Full diff: https://github.com/llvm/llvm-project/pull/160675.diff


1 Files Affected:

- (modified) lldb/packages/Python/lldbsuite/test/cpu_feature.py (+10-3) 


``````````diff
diff --git a/lldb/packages/Python/lldbsuite/test/cpu_feature.py b/lldb/packages/Python/lldbsuite/test/cpu_feature.py
index 3f43cbba130c0..9cdf46d688dd1 100644
--- a/lldb/packages/Python/lldbsuite/test/cpu_feature.py
+++ b/lldb/packages/Python/lldbsuite/test/cpu_feature.py
@@ -39,9 +39,16 @@ def _is_supported_linux(self, cmd_runner):
         if err.Fail() or retcode != 0:
             return output, False
 
-        # FIXME: simple substring match, e.g., test for 'sme' will be true if
-        # 'sme2' or 'smefa64' is present
-        return None, (self.cpu_info_flag in output)
+        # Assume that every processor presents the same features.
+        # Look for the first "Features: ...." line.
+        for line in output.splitlines():
+            line = line.strip()
+            if line.startswith("Features"):
+                # Feature names are space separated.
+                features = line.split(":")[1].strip().split()
+                return None, (self.cpu_info_flag in features)
+
+        return f'No "Features:" line found in /proc/cpuinfo', False
 
     def _is_supported_darwin(self, cmd_runner):
         if not self.sysctl_key:

``````````

</details>


https://github.com/llvm/llvm-project/pull/160675