[Lldb-commits] [lldb] bb9d93f - [lldb] Replace the LEB128 decoding logic in LLDB's DataExtractor with calls to LLVM's LEB128 implementation

[Raphael Isemann via lldb-commits]

Author: Raphael Isemann
Date: 2020-06-10T16:35:09+02:00
New Revision: bb9d93f4d5934259fa2a55aabfda89e631e02037

URL: https://github.com/llvm/llvm-project/commit/bb9d93f4d5934259fa2a55aabfda89e631e02037
DIFF: https://github.com/llvm/llvm-project/commit/bb9d93f4d5934259fa2a55aabfda89e631e02037.diff

LOG: [lldb] Replace the LEB128 decoding logic in LLDB's DataExtractor with calls to LLVM's LEB128 implementation

Reviewers: labath, JDevlieghere

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D81453

Added: 
    

Modified: 
    lldb/source/Utility/DataExtractor.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Utility/DataExtractor.cpp b/lldb/source/Utility/DataExtractor.cpp
index 023190b2ae91..365ee58bb95b 100644
--- a/lldb/source/Utility/DataExtractor.cpp
+++ b/lldb/source/Utility/DataExtractor.cpp
@@ -24,6 +24,7 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/LEB128.h"
 #include "llvm/Support/MD5.h"
 #include "llvm/Support/MathExtras.h"
 
@@ -877,26 +878,10 @@ uint64_t DataExtractor::GetULEB128(offset_t *offset_ptr) const {
   if (src == nullptr)
     return 0;
 
-  const uint8_t *end = m_end;
-
-  if (src < end) {
-    uint64_t result = *src++;
-    if (result >= 0x80) {
-      result &= 0x7f;
-      int shift = 7;
-      while (src < end) {
-        uint8_t byte = *src++;
-        result |= static_cast<uint64_t>(byte & 0x7f) << shift;
-        if ((byte & 0x80) == 0)
-          break;
-        shift += 7;
-      }
-    }
-    *offset_ptr = src - m_start;
-    return result;
-  }
-
-  return 0;
+  unsigned byte_count = 0;
+  uint64_t result = llvm::decodeULEB128(src, &byte_count, m_end);
+  *offset_ptr += byte_count;
+  return result;
 }
 
 // Extracts an signed LEB128 number from this object's data starting at the
@@ -910,35 +895,10 @@ int64_t DataExtractor::GetSLEB128(offset_t *offset_ptr) const {
   if (src == nullptr)
     return 0;
 
-  const uint8_t *end = m_end;
-
-  if (src < end) {
-    int64_t result = 0;
-    int shift = 0;
-    int size = sizeof(int64_t) * 8;
-
-    uint8_t byte = 0;
-    int bytecount = 0;
-
-    while (src < end) {
-      bytecount++;
-      byte = *src++;
-      result |= static_cast<int64_t>(byte & 0x7f) << shift;
-      shift += 7;
-      if ((byte & 0x80) == 0)
-        break;
-    }
-
-    // Sign bit of byte is 2nd high order bit (0x40)
-    if (shift < size && (byte & 0x40)) {
-      // -(static_cast<int64_t>(1) << 63) errors on the negation with UBSan.
-      result |= -(static_cast<uint64_t>(1) << shift);
-    }
-
-    *offset_ptr += bytecount;
-    return result;
-  }
-  return 0;
+  unsigned byte_count = 0;
+  int64_t result = llvm::decodeSLEB128(src, &byte_count, m_end);
+  *offset_ptr += byte_count;
+  return result;
 }
 
 // Skips a ULEB128 number (signed or unsigned) from this object's data starting