Adjust a ValueObjectChild's offset when the child is a bitfield

If a bitfield doesn't fit into the child_byte_size'd window at
child_byte_offset, move the window forward until it fits.  The problem
here is that Value has no notion of bitfields and thus the Value's
DataExtractor is sized like the bitfields CompilerType; a sequence of
bitfields, however, can be larger than their underlying type.

This was not in the big-endian-derived DWARF 2 bitfield attributes
because their offsets were counted from the end of the window, so they
always fit.

rdar://problem/53132189

Differential Revision: https://reviews.llvm.org/D65492

llvm-svn: 368226

2 files changed, 11 insertions, 0 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/lang/c/bitfields/TestBitfields.py b/lldb/packages/Python/lldbsuite/test/lang/c/bitfields/TestBitfields.py
index c1a32f2ee09..d5580ac86cc 100644
--- a/lldb/packages/Python/lldbsuite/test/lang/c/bitfields/TestBitfields.py
+++ b/lldb/packages/Python/lldbsuite/test/lang/c/bitfields/TestBitfields.py
@@ -146,6 +146,9 @@ class BitfieldsTestCase(TestBase):
                 '(uint8_t:1) b17 = \'\\0\'',
                 ])
 
+        self.expect("v/x large_packed", VARIABLES_DISPLAYED_CORRECTLY,
+                    substrs=["a = 0x0000000cbbbbaaaa", "b = 0x0000000dffffeee"])
+
 
     @add_test_categories(['pyapi'])
     # BitFields exhibit crashes in record layout on Windows
diff --git a/lldb/packages/Python/lldbsuite/test/lang/c/bitfields/main.c b/lldb/packages/Python/lldbsuite/test/lang/c/bitfields/main.c
index c21cfc9a9fb..35faac3b6c3 100644
--- a/lldb/packages/Python/lldbsuite/test/lang/c/bitfields/main.c
+++ b/lldb/packages/Python/lldbsuite/test/lang/c/bitfields/main.c
@@ -90,6 +90,14 @@ int main (int argc, char const *argv[])
     packed.b = 10;
     packed.c = 0x7112233;
 
+    struct LargePackedBits {
+        unsigned long a: 36;
+        unsigned long b: 36;
+    } __attribute__((packed));
+
+    struct LargePackedBits large_packed =
+      (struct LargePackedBits){ 0xcbbbbaaaa, 0xdffffeeee };
+    
     return 0;               //// Set break point at this line.
 
 }