Reland "[lldb] Do not bump memory modificator ID when "internal" debugger memory is updated (#129092)"

This reverts commit daa4061d61216456baa83ab404e096200e327fb4.

Original PR https://github.com/llvm/llvm-project/pull/129092.

I have restricted the test to X86 Windows because it turns out the only
reason that `expr x.get()` would change m_memory_id is that on x86 we
have to write the return address to the stack in ABIWindows_X86_64::PrepareTrivialCall:
```
  // Save return address onto the stack
  if (!process_sp->WritePointerToMemory(sp, return_addr, error))
    return false;
```

This is not required on AArch64 so m_memory_id was not changed:
```
(lldb) expr x.get()
(int) $0 = 0
(lldb) process status -d
Process 15316 stopped
* thread #1, stop reason = Exception 0x80000003 encountered at address 0x7ff764a31034
    frame #0: 0x00007ff764a31038 TestProcessModificationIdOnExpr.cpp.tmp`main at TestProcessModificationIdOnExpr.cpp:35
   32     __builtin_debugtrap();
   33     __builtin_debugtrap();
   34     return 0;
-> 35   }
   36
   37   // CHECK-LABEL: process status -d
   38   // CHECK: m_stop_id: 2
ProcessModID:
  m_stop_id: 3
  m_last_natural_stop_id: 0
  m_resume_id: 0
  m_memory_id: 0
```

Really we should find a better way to force a memory write here, but
I can't think of one right now.

1 files changed, 55 insertions, 0 deletions

diff --git a/lldb/test/Shell/Expr/TestExprWithSideEffect.cpp b/lldb/test/Shell/Expr/TestExprWithSideEffect.cpp
new file mode 100644
index 000000000000..4fc88b62730c
--- /dev/null
+++ b/lldb/test/Shell/Expr/TestExprWithSideEffect.cpp
@@ -0,0 +1,55 @@
+// Tests evaluating expressions with side effects.
+// Applied side effect should be visible to the debugger.
+
+// RUN: %build %s -o %t
+// RUN: %lldb %t \
+// RUN:   -o "settings set target.process.track-memory-cache-changes false" \
+// RUN:   -o "run" \
+// RUN:   -o "frame variable x" \
+// RUN:   -o "expr x.inc()" \
+// RUN:   -o "frame variable x" \
+// RUN:   -o "continue" \
+// RUN:   -o "frame variable x" \
+// RUN:   -o "expr x.i = 10" \
+// RUN:   -o "frame variable x" \
+// RUN:   -o "continue" \
+// RUN:   -o "frame variable x" \
+// RUN:   -o "exit" | FileCheck %s -dump-input=fail
+
+class X {
+  int i = 0;
+
+public:
+  void inc() { ++i; }
+};
+
+int main() {
+  X x;
+  x.inc();
+
+  __builtin_debugtrap();
+  __builtin_debugtrap();
+  __builtin_debugtrap();
+  return 0;
+}
+
+// CHECK-LABEL: frame variable x
+// CHECK: (X) x = (i = 1)
+
+// CHECK-LABEL: expr x.inc()
+// CHECK-LABEL: frame variable x
+// CHECK: (X) x = (i = 2)
+
+// CHECK-LABEL: continue
+// CHECK-LABEL: frame variable x
+// CHECK: (X) x = (i = 2)
+
+// CHECK-LABEL: expr x.i = 10
+// CHECK: (int) $0 = 10
+
+// CHECK-LABEL: frame variable x
+// CHECK: (X) x = (i = 10)
+
+// CHECK-LABEL: continue
+// CHECK-LABEL: frame variable x
+// CHECK: (X) x = (i = 10)