Added GDB pretty printer for StringMap

Reviewed By: csigg, dblaikie

Differential Revision: https://reviews.llvm.org/D91183

debuginfo-tests/llvm-prettyprinters/gdb/llvm-support.cpp

@@ -5,6 +5,7 @@
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/ADT/ilist.h"
 #include "llvm/Support/Error.h"
@@ -15,6 +16,7 @@ auto IntPtr = reinterpret_cast<int *>(0xabc);
 llvm::ArrayRef<int> ArrayRef(Array);
 llvm::MutableArrayRef<int> MutableArrayRef(Array);
 llvm::DenseMap<int, int> DenseMap = {{4, 5}, {6, 7}};
+llvm::StringMap<int> StringMap = {{"foo", 123}, {"bar", 456}};
 llvm::Expected<int> ExpectedValue(8);
 llvm::Expected<int> ExpectedError(llvm::createStringError({}, ""));
 llvm::Optional<int> OptionalValue(9);

debuginfo-tests/llvm-prettyprinters/gdb/llvm-support.gdb

@@ -40,6 +40,9 @@ p StringRef
 # CHECK: "\"foo\"\"bar\""
 p Twine
 
+# CHECK: llvm::StringMap with 2 elements = {["foo"] = 123, ["bar"] = 456}
+p StringMap
+
 # CHECK: {pointer = 0xabc, value = 1}
 p PointerIntPair
 

llvm/include/llvm/ADT/StringMap.h

@@ -78,10 +78,12 @@ class StringMapImpl {
   void init(unsigned Size);
 
 public:
+  static constexpr uintptr_t TombstoneIntVal =
+      static_cast<uintptr_t>(-1)
+      << PointerLikeTypeTraits<StringMapEntryBase *>::NumLowBitsAvailable;
+
   static StringMapEntryBase *getTombstoneVal() {
-    uintptr_t Val = static_cast<uintptr_t>(-1);
-    Val <<= PointerLikeTypeTraits<StringMapEntryBase *>::NumLowBitsAvailable;
-    return reinterpret_cast<StringMapEntryBase *>(Val);
+    return reinterpret_cast<StringMapEntryBase *>(TombstoneIntVal);
   }
 
   unsigned getNumBuckets() const { return NumBuckets; }

llvm/utils/gdb-scripts/prettyprinters.py

@@ -1,4 +1,5 @@
 from __future__ import print_function
+import struct
 import sys
 
 import gdb.printing
@@ -200,6 +201,44 @@ def to_string(self):
   def display_hint(self):
     return 'map'
 
+class StringMapPrinter:
+  "Print a StringMap"
+
+  def __init__(self, val):
+    self.val = val
+
+  def children(self):
+    it = self.val['TheTable']
+    end = (it + self.val['NumBuckets'])
+    value_ty = self.val.type.template_argument(0)
+    entry_ty = gdb.lookup_type('llvm::StringMapEntry<{}>'.format(value_ty.name))
+    tombstone = gdb.parse_and_eval('llvm::StringMapImpl::TombstoneIntVal');
+
+    while it != end:
+      it_deref = it.dereference()
+      if it_deref == 0 or it_deref == tombstone:
+        it = it + 1
+        continue
+
+      entry_ptr = it_deref.cast(entry_ty.pointer())
+      entry = entry_ptr.dereference()
+
+      str_len = entry['keyLength']
+      str_data = (entry_ptr + 1).cast(gdb.lookup_type('char').const().pointer())
+      string_ref = gdb.Value(struct.pack('PN', int(str_data), int(str_len)), gdb.lookup_type('llvm::StringRef'))
+      yield 'key', string_ref
+
+      value = entry['second']
+      yield 'value', value
+
+      it = it + 1
+
+  def to_string(self):
+    return 'llvm::StringMap with %d elements' % (self.val['NumItems'])
+
+  def display_hint(self):
+    return 'map'
+
 class TwinePrinter:
   "Print a Twine"
 
@@ -442,6 +481,7 @@ def children(self):
 pp.add_printer('llvm::Expected', '^llvm::Expected<.*>$', ExpectedPrinter)
 pp.add_printer('llvm::Optional', '^llvm::Optional<.*>$', OptionalPrinter)
 pp.add_printer('llvm::DenseMap', '^llvm::DenseMap<.*>$', DenseMapPrinter)
+pp.add_printer('llvm::StringMap', '^llvm::StringMap<.*>$', StringMapPrinter)
 pp.add_printer('llvm::Twine', '^llvm::Twine$', TwinePrinter)
 pp.add_printer('llvm::PointerIntPair', '^llvm::PointerIntPair<.*>$', make_pointer_int_pair_printer)
 pp.add_printer('llvm::PointerUnion', '^llvm::PointerUnion<.*>$', make_pointer_union_printer)