Add an LLDB data formatter script for llvm::SmallVector, maybe this is helpful to someone else.

This lets lldb give sane output for SmallVectors, e.g.
Before:
(lldb) p sv
(llvm::SmallVector<int, 10>) $0 = {
  (llvm::SmallVectorImpl<int>) llvm::SmallVectorImpl<int> = {
    (llvm::SmallVectorTemplateBase<int>) llvm::SmallVectorTemplateBase<int> = {
      (llvm::SmallVectorTemplateCommon<int>) llvm::SmallVectorTemplateCommon<int> = {
        (llvm::SmallVectorBase) llvm::SmallVectorBase = {
          (void *) BeginX = 0x00007fff5fbff960
...
}

After:
(lldb) p sv
(llvm::SmallVector<int, 10>) $0 = {
  (int) [0] = 42
  (int) [1] = 23
...
}

The script is still a bit rough so expect crashes for vectors of complex types.
Synthetic children are _not_ available in xcode 4.2, newer LLDBs should work though.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148308 91177308-0d34-0410-b5e6-96231b3b80d8

utils/lldbDataFormatters.py

@@ -0,0 +1,53 @@
+"""
+Load into LLDB with:
+script import lldbDataFormatters
+type synthetic add -x "^llvm::SmallVectorImpl<.+>$" -l lldbDataFormatters.SmallVectorSynthProvider
+"""
+
+# Pretty printer for llvm::SmallVector/llvm::SmallVectorImpl
+class SmallVectorSynthProvider:
+    def __init__(self, valobj, dict):
+        self.valobj = valobj;
+        self.update() # initialize this provider
+
+    def num_children(self):
+        begin = self.begin.GetValueAsUnsigned(0)
+        end = self.end.GetValueAsUnsigned(0)
+        return (end - begin)/self.type_size
+
+    def get_child_index(self, name):
+        try:
+            return int(name.lstrip('[').rstrip(']'))
+        except:
+            return -1;
+
+    def get_child_at_index(self, index):
+        # Do bounds checking.
+        if index < 0:
+            return None
+        if index >= self.num_children():
+            return None;
+
+        offset = index * self.type_size
+        return self.begin.CreateChildAtOffset('['+str(index)+']',
+                                              offset, self.data_type)
+
+    def get_type_from_name(self):
+        import re
+        name = self.valobj.GetType().GetName()
+        # This class works with both SmallVectors and SmallVectorImpls.
+        res = re.match("^(llvm::)?SmallVectorImpl<(.+)>$", name)
+        if res:
+            return res.group(2)
+        res = re.match("^(llvm::)?SmallVector<(.+), \d+>$", name)
+        if res:
+            return res.group(2)
+        return None
+
+    def update(self):
+        self.begin = self.valobj.GetChildMemberWithName('BeginX')
+        self.end = self.valobj.GetChildMemberWithName('EndX')
+        data_type = self.get_type_from_name()
+        # FIXME: this sometimes returns an invalid type.
+        self.data_type = self.valobj.GetTarget().FindFirstType(data_type)
+        self.type_size = self.data_type.GetByteSize()