[lldb] add SBSection.alignment to python bindings

This commit adds SBSection.GetAlignment(), and SBSection.alignment as a python property to lldb.

Reviewed By: clayborg, JDevlieghere, labath

Differential Revision: https://reviews.llvm.org/D128069

Author: dmlary

lldb/bindings/interface/SBSection.i

@@ -105,6 +105,9 @@ public:
     uint32_t
     GetTargetByteSize ();
 
+    uint32_t
+    GetAlignment ();
+
     bool
     GetDescription (lldb::SBStream &description);
 
@@ -138,6 +141,7 @@ public:
         data = property(GetSectionData, None, doc='''A read only property that returns an lldb object that represents the bytes for this section (lldb.SBData) for this section.''')
         type = property(GetSectionType, None, doc='''A read only property that returns an lldb enumeration value (see enumerations that start with "lldb.eSectionType") that represents the type of this section (code, data, etc.).''')
         target_byte_size = property(GetTargetByteSize, None, doc='''A read only property that returns the size of a target byte represented by this section as a number of host bytes.''')
+        alignment = property(GetAlignment, None, doc='''A read only property that returns the alignment of this section as a number of host bytes.''')
     %}
 #endif
 

lldb/include/lldb/API/SBSection.h

@@ -76,6 +76,12 @@ class LLDB_API SBSection {
   ///     The number of host (8-bit) bytes needed to hold a target byte
   uint32_t GetTargetByteSize();
 
+  /// Return the alignment of the section in bytes
+  ///
+  /// \return
+  ///     The alignment of the section in bytes
+  uint32_t GetAlignment();
+
   bool operator==(const lldb::SBSection &rhs);
 
   bool operator!=(const lldb::SBSection &rhs);

lldb/source/API/SBSection.cpp

@@ -242,6 +242,15 @@ uint32_t SBSection::GetTargetByteSize() {
   return 0;
 }
 
+uint32_t SBSection::GetAlignment() {
+  LLDB_INSTRUMENT_VA(this);
+
+  SectionSP section_sp(GetSP());
+  if (section_sp.get())
+    return (1 << section_sp->GetLog2Align());
+  return 0;
+}
+
 bool SBSection::operator==(const SBSection &rhs) {
   LLDB_INSTRUMENT_VA(this, rhs);
 

lldb/test/API/python_api/section/TestSectionAPI.py

@@ -37,3 +37,14 @@ def test_get_target_byte_size(self):
 
         self.assertIsNotNone(data_section)
         self.assertEqual(data_section.target_byte_size, 1)
+
+    def test_get_alignment(self):
+        exe = self.getBuildArtifact("aligned.out")
+        self.yaml2obj("aligned.yaml", exe)
+        target = self.dbg.CreateTarget(exe)
+        self.assertTrue(target, VALID_TARGET)
+
+        # exe contains a single section aligned to 0x1000
+        section = target.modules[0].sections[0]
+        self.assertEqual(section.GetAlignment(), 0x1000)
+        self.assertEqual(section.alignment, 0x1000)

lldb/test/API/python_api/section/aligned.yaml

@@ -0,0 +1,14 @@
+--- !ELF
+FileHeader:      
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+  Entry:           0x0000000000400000
+Sections:        
+  - Name:            .text1
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x0000000000400000
+    AddressAlign:    0x0000000000001000
+    Size:            0xb0