[lldb] Speed up FindInMemory tests (#111951)

A memory region can be relatively large. Searching for a value in the
entire region is time-consuming, especially when running tests against a
remote target, because the memory data is transferred in small chunks
over a relatively slow GDB Remote Protocol. The patch limits the address
range to be searched to 2K, which seems sufficient for these tests. In
my setup, for local runs, these tests now take half the time they did
before the patch. For a remote target, the improvement is even more
significant.

Author: igorkudrin

lldb/test/API/python_api/find_in_memory/TestFindInMemory.py

@@ -55,7 +55,7 @@ def test_find_in_memory_ok(self):
         error = lldb.SBError()
         addr = self.process.FindInMemory(
             SINGLE_INSTANCE_PATTERN_STACK,
-            GetStackRange(self),
+            GetStackRange(self, True),
             1,
             error,
         )
@@ -70,7 +70,7 @@ def test_find_in_memory_double_instance_ok(self):
         error = lldb.SBError()
         addr = self.process.FindInMemory(
             DOUBLE_INSTANCE_PATTERN_HEAP,
-            GetHeapRanges(self)[0],
+            GetHeapRanges(self, True)[0],
             1,
             error,
         )
@@ -86,7 +86,7 @@ def test_find_in_memory_invalid_alignment(self):
         error = lldb.SBError()
         addr = self.process.FindInMemory(
             SINGLE_INSTANCE_PATTERN_STACK,
-            GetStackRange(self),
+            GetStackRange(self, True),
             0,
             error,
         )
@@ -118,7 +118,7 @@ def test_find_in_memory_invalid_buffer(self):
         error = lldb.SBError()
         addr = self.process.FindInMemory(
             "",
-            GetStackRange(self),
+            GetStackRange(self, True),
             1,
             error,
         )
@@ -131,7 +131,7 @@ def test_find_in_memory_unaligned(self):
         self.assertTrue(self.process, PROCESS_IS_VALID)
         self.assertState(self.process.GetState(), lldb.eStateStopped, PROCESS_STOPPED)
         error = lldb.SBError()
-        range = GetAlignedRange(self)
+        range = GetAlignedRange(self, True)
 
         # First we make sure the pattern is found with alignment 1
         addr = self.process.FindInMemory(

lldb/test/API/python_api/find_in_memory/TestFindRangesInMemory.py

@@ -30,7 +30,7 @@ def test_find_ranges_in_memory_two_matches(self):
         self.assertTrue(self.process, PROCESS_IS_VALID)
         self.assertState(self.process.GetState(), lldb.eStateStopped, PROCESS_STOPPED)
 
-        addr_ranges = GetHeapRanges(self)
+        addr_ranges = GetHeapRanges(self, True)
         error = lldb.SBError()
         matches = self.process.FindRangesInMemory(
             DOUBLE_INSTANCE_PATTERN_HEAP,
@@ -48,7 +48,7 @@ def test_find_ranges_in_memory_one_match(self):
         self.assertTrue(self.process, PROCESS_IS_VALID)
         self.assertState(self.process.GetState(), lldb.eStateStopped, PROCESS_STOPPED)
 
-        addr_ranges = GetStackRanges(self)
+        addr_ranges = GetStackRanges(self, True)
         error = lldb.SBError()
         matches = self.process.FindRangesInMemory(
             SINGLE_INSTANCE_PATTERN_STACK,
@@ -66,7 +66,7 @@ def test_find_ranges_in_memory_one_match_multiple_ranges(self):
         self.assertTrue(self.process, PROCESS_IS_VALID)
         self.assertState(self.process.GetState(), lldb.eStateStopped, PROCESS_STOPPED)
 
-        addr_ranges = GetRanges(self)
+        addr_ranges = GetRanges(self, True)
         addr_ranges.Append(lldb.SBAddressRange())
         self.assertGreater(addr_ranges.GetSize(), 2)
         error = lldb.SBError()
@@ -86,7 +86,7 @@ def test_find_ranges_in_memory_one_match_max(self):
         self.assertTrue(self.process, PROCESS_IS_VALID)
         self.assertState(self.process.GetState(), lldb.eStateStopped, PROCESS_STOPPED)
 
-        addr_ranges = GetHeapRanges(self)
+        addr_ranges = GetHeapRanges(self, True)
         error = lldb.SBError()
         matches = self.process.FindRangesInMemory(
             DOUBLE_INSTANCE_PATTERN_HEAP,
@@ -104,7 +104,7 @@ def test_find_ranges_in_memory_invalid_alignment(self):
         self.assertTrue(self.process, PROCESS_IS_VALID)
         self.assertState(self.process.GetState(), lldb.eStateStopped, PROCESS_STOPPED)
 
-        addr_ranges = GetHeapRanges(self)
+        addr_ranges = GetHeapRanges(self, True)
         error = lldb.SBError()
         matches = self.process.FindRangesInMemory(
             DOUBLE_INSTANCE_PATTERN_HEAP,
@@ -160,7 +160,7 @@ def test_find_ranges_in_memory_invalid_buffer(self):
         self.assertTrue(self.process, PROCESS_IS_VALID)
         self.assertState(self.process.GetState(), lldb.eStateStopped, PROCESS_STOPPED)
 
-        addr_ranges = GetHeapRanges(self)
+        addr_ranges = GetHeapRanges(self, True)
         error = lldb.SBError()
         matches = self.process.FindRangesInMemory(
             "",
@@ -178,7 +178,7 @@ def test_find_ranges_in_memory_invalid_max_matches(self):
         self.assertTrue(self.process, PROCESS_IS_VALID)
         self.assertState(self.process.GetState(), lldb.eStateStopped, PROCESS_STOPPED)
 
-        addr_ranges = GetHeapRanges(self)
+        addr_ranges = GetHeapRanges(self, True)
         error = lldb.SBError()
         matches = self.process.FindRangesInMemory(
             DOUBLE_INSTANCE_PATTERN_HEAP,
@@ -197,7 +197,7 @@ def test_find_in_memory_unaligned(self):
         self.assertState(self.process.GetState(), lldb.eStateStopped, PROCESS_STOPPED)
 
         addr_ranges = lldb.SBAddressRangeList()
-        addr_ranges.Append(GetAlignedRange(self))
+        addr_ranges.Append(GetAlignedRange(self, True))
         error = lldb.SBError()
 
         matches = self.process.FindRangesInMemory(

lldb/test/API/python_api/find_in_memory/address_ranges_helper.py

@@ -6,27 +6,30 @@
 UNALIGNED_INSTANCE_PATTERN_HEAP = ALIGNED_INSTANCE_PATTERN_HEAP[1:]
 
 
-def GetAlignedRange(test_base):
+def GetAlignedRange(test_base, shrink=False):
     frame = test_base.thread.GetSelectedFrame()
     ex = frame.EvaluateExpression("aligned_string_ptr")
     test_base.assertTrue(ex.IsValid())
-    return GetRangeFromAddrValue(test_base, ex)
+    return GetRangeFromAddrValue(test_base, ex, shrink)
 
 
-def GetStackRange(test_base):
+def GetStackRange(test_base, shrink=False):
     frame = test_base.thread.GetSelectedFrame()
     ex = frame.EvaluateExpression("&stack_pointer")
     test_base.assertTrue(ex.IsValid())
-    return GetRangeFromAddrValue(test_base, ex)
+    return GetRangeFromAddrValue(test_base, ex, shrink)
 
 
-def GetStackRanges(test_base):
+def GetStackRanges(test_base, shrink=False):
     addr_ranges = lldb.SBAddressRangeList()
     addr_ranges.Append(GetStackRange(test_base))
     return addr_ranges
 
 
-def GetRangeFromAddrValue(test_base, addr):
+def GetRangeFromAddrValue(test_base, addr, shrink=False):
+    """Returns a memory region containing 'addr'.
+    If 'shrink' is True, the address range will be reduced to not exceed 2K.
+    """
     region = lldb.SBMemoryRegionInfo()
     test_base.assertTrue(
         test_base.process.GetMemoryRegionInfo(
@@ -37,37 +40,48 @@ def GetRangeFromAddrValue(test_base, addr):
     test_base.assertTrue(region.IsReadable())
     test_base.assertFalse(region.IsExecutable())
 
-    address_start = lldb.SBAddress(region.GetRegionBase(), test_base.target)
-    stack_size = region.GetRegionEnd() - region.GetRegionBase()
-    return lldb.SBAddressRange(address_start, stack_size)
+    base = region.GetRegionBase()
+    end = region.GetRegionEnd()
 
+    if shrink:
+        addr2 = addr.GetValueAsUnsigned()
+        addr2 -= addr2 % 512
+        base = max(base, addr2 - 1024)
+        end = min(end, addr2 + 1024)
 
-def IsWithinRange(addr, range, target):
+    start = lldb.SBAddress(base, test_base.target)
+    size = end - base
+
+    return lldb.SBAddressRange(start, size)
+
+
+def IsWithinRange(addr, size, range, target):
     start_addr = range.GetBaseAddress().GetLoadAddress(target)
     end_addr = start_addr + range.GetByteSize()
     addr = addr.GetValueAsUnsigned()
-    return addr >= start_addr and addr < end_addr
+    return addr >= start_addr and addr + size <= end_addr
 
 
-def GetHeapRanges(test_base):
+def GetHeapRanges(test_base, shrink=False):
     frame = test_base.thread.GetSelectedFrame()
 
     ex = frame.EvaluateExpression("heap_pointer1")
     test_base.assertTrue(ex.IsValid())
-    range = GetRangeFromAddrValue(test_base, ex)
+    range = GetRangeFromAddrValue(test_base, ex, shrink)
     addr_ranges = lldb.SBAddressRangeList()
     addr_ranges.Append(range)
 
     ex = frame.EvaluateExpression("heap_pointer2")
     test_base.assertTrue(ex.IsValid())
-    if not IsWithinRange(ex, addr_ranges[0], test_base.target):
-        addr_ranges.Append(GetRangeFromAddrValue(test_base, ex))
+    size = len(DOUBLE_INSTANCE_PATTERN_HEAP)
+    if not IsWithinRange(ex, size, addr_ranges[0], test_base.target):
+        addr_ranges.Append(GetRangeFromAddrValue(test_base, ex, shrink))
 
     return addr_ranges
 
 
-def GetRanges(test_base):
-    ranges = GetHeapRanges(test_base)
-    ranges.Append(GetStackRanges(test_base))
+def GetRanges(test_base, shrink=False):
+    ranges = GetHeapRanges(test_base, shrink)
+    ranges.Append(GetStackRanges(test_base, shrink))
 
     return ranges