[Lldb-commits] [lldb] [lldb] [unittests] Cover what the memory cache reads from the inferior (PR #221015)

[Yao Qi via lldb-commits]

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@@ -489,6 +497,168 @@ TEST_F(MemoryTest, TestReadStopsAtAnInvalidRange) {
   EXPECT_TRUE(process->m_reads.empty());
 }
 
+TEST_F(MemoryTest, TestReadRangesFromCaches) {
+  CacheTestProcess proc;
+  ASSERT_TRUE(proc.process());
+  DummyProcess *process = proc.process();
+  const lldb::addr_t line = proc.line();
+
+  { // A short fetch must expose only the bytes it read, and must not disturb a
+    // range the caches already served.
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qiyao wrote:

It destroys it, yes.  `AddL1CacheData` is `m_L1_cache[addr] = data_buffer_sp`, so the 20 bytes the fetch returned replace the 40-byte chunk outright.  I add a couple of asserts on L1 cache chunks.

my "must not disturb a range the caches already served" was ambiguous about `0xC000` range instead of `0xB000` range.  `0xB000` was never served: 40 bytes cannot cover the 64 asked for, so `FindCacheEntry` misses and the range is fetched.  I changed the comments
```
  { // An entry serves a range only if it covers it all.  A short fetch is all
    // the caller sees and all L1 keeps of the range it was for.
```

https://github.com/llvm/llvm-project/pull/221015