[LLDB] Add a setting for printing ValueObject hex values without leading zeroes (llvm#66548)

As suggested by Greg in llvm#66534,
I'm adding a setting at the Target level that controls whether to show
leading zeroes in hex ValueObject values.

This has the benefit of reducing the amount of characters displayed in
certain interfaces, like VSCode.

Author: walter-erquinigo

lldb/include/lldb/Target/Target.h

@@ -167,6 +167,8 @@ class TargetProperties : public Properties {
 
   bool GetEnableSyntheticValue() const;
 
+  bool ShowHexVariableValuesWithLeadingZeroes() const;
+
   uint32_t GetMaxZeroPaddingInFloatFormat() const;
 
   uint32_t GetMaximumNumberOfChildrenToDisplay() const;

lldb/source/Core/DumpDataExtractor.cpp

@@ -620,10 +620,17 @@ lldb::offset_t lldb_private::DumpDataExtractor(
       case 2:
       case 4:
       case 8:
-        s->Printf(wantsuppercase ? "0x%*.*" PRIX64 : "0x%*.*" PRIx64,
-                  (int)(2 * item_byte_size), (int)(2 * item_byte_size),
-                  DE.GetMaxU64Bitfield(&offset, item_byte_size, item_bit_size,
-                                       item_bit_offset));
+        if (Target::GetGlobalProperties()
+                .ShowHexVariableValuesWithLeadingZeroes()) {
+          s->Printf(wantsuppercase ? "0x%*.*" PRIX64 : "0x%*.*" PRIx64,
+                    (int)(2 * item_byte_size), (int)(2 * item_byte_size),
+                    DE.GetMaxU64Bitfield(&offset, item_byte_size, item_bit_size,
+                                         item_bit_offset));
+        } else {
+          s->Printf(wantsuppercase ? "0x%" PRIX64 : "0x%" PRIx64,
+                    DE.GetMaxU64Bitfield(&offset, item_byte_size, item_bit_size,
+                                         item_bit_offset));
+        }
         break;
       default: {
         assert(item_bit_size == 0 && item_bit_offset == 0);

lldb/source/Target/Target.cpp

@@ -4236,8 +4236,8 @@ bool TargetProperties::SetPreferDynamicValue(lldb::DynamicValueType d) {
 }
 
 bool TargetProperties::GetPreloadSymbols() const {
-  if (INTERRUPT_REQUESTED(m_target->GetDebugger(), 
-      "Interrupted checking preload symbols")) {
+  if (INTERRUPT_REQUESTED(m_target->GetDebugger(),
+                          "Interrupted checking preload symbols")) {
     return false;
   }
   const uint32_t idx = ePropertyPreloadSymbols;
@@ -4539,6 +4539,12 @@ bool TargetProperties::GetEnableSyntheticValue() const {
       idx, g_target_properties[idx].default_uint_value != 0);
 }
 
+bool TargetProperties::ShowHexVariableValuesWithLeadingZeroes() const {
+  const uint32_t idx = ePropertyShowHexVariableValuesWithLeadingZeroes;
+  return GetPropertyAtIndexAs<bool>(
+      idx, g_target_properties[idx].default_uint_value != 0);
+}
+
 uint32_t TargetProperties::GetMaxZeroPaddingInFloatFormat() const {
   const uint32_t idx = ePropertyMaxZeroPaddingInFloatFormat;
   return GetPropertyAtIndexAs<uint64_t>(

lldb/source/Target/TargetProperties.td

@@ -82,6 +82,10 @@ let Definition = "target" in {
   def SaveObjectsDir: Property<"save-jit-objects-dir", "FileSpec">,
     DefaultStringValue<"">,
     Desc<"If specified, the directory to save intermediate object files generated by the LLVM JIT">;
+  def ShowHexVariableValuesWithLeadingZeroes: Property<"show-hex-variable-values-with-leading-zeroes", "Boolean">,
+    Global,
+    DefaultTrue,
+    Desc<"Whether to display leading zeroes when printing variable values in hex format.">;
   def MaxZeroPaddingInFloatFormat: Property<"max-zero-padding-in-float-format", "UInt64">,
     DefaultUnsignedValue<6>,
     Desc<"The maximum number of zeroes to insert when displaying a very small float before falling back to scientific notation.">;

lldb/test/API/python_api/value/TestValueAPI.py

@@ -3,9 +3,9 @@
 """
 
 import lldb
+from lldbsuite.test import lldbutil
 from lldbsuite.test.decorators import *
 from lldbsuite.test.lldbtest import *
-from lldbsuite.test import lldbutil
 
 
 class ValueAPITestCase(TestBase):
@@ -206,3 +206,18 @@ def test(self):
             -526164208,
             "signed sinthex == -526164208",
         )
+
+        # Check that hex value printing works as expected.
+        self.assertEqual(
+            frame0.FindVariable("fixed_int_ptr").GetValue(),
+            "0x00000000000000aa",
+        )
+        self.runCmd("settings set target.show-hex-values-with-leading-zeroes false")
+        self.assertEqual(
+            frame0.FindVariable("another_fixed_int_ptr").GetValue(),
+            "0xaa",
+        )
+        self.assertEqual(
+            frame0.FindVariable("a_null_int_ptr").GetValue(),
+            "0x0",
+        )

lldb/test/API/python_api/value/main.c

@@ -44,13 +44,16 @@ int main (int argc, char const *argv[])
     int i;
     MyInt a = 12345;
     struct MyStruct s = { 11, 22 };
-    struct MyBiggerStruct f = { 33, 44, 55 }; 
+    struct MyBiggerStruct f = { 33, 44, 55 };
     int *my_int_ptr = &g_my_int;
     printf("my_int_ptr points to location %p\n", my_int_ptr);
+    int *fixed_int_ptr = (int*)(void*)0xAA;
+    int *another_fixed_int_ptr = (int*)(void*)0xAA;
+    int *a_null_int_ptr = NULL;
     const char **str_ptr = days_of_week;
     for (i = 0; i < 7; ++i)
         printf("%s\n", str_ptr[i]); // Break at this line
                                     // and do str_ptr_val.GetChildAtIndex(5, lldb.eNoDynamicValues, True).
-    
+
     return 0;
 }