[Lldb-commits] [PATCH] D81453: [lldb] Replace the LEB128 decoding logic in LLDB's DataExtractor with calls to LLVM's LEB128 implementation

[Raphael Isemann via Phabricator via lldb-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGbb9d93f4d593: [lldb] Replace the LEB128 decoding logic in 
LLDB's DataExtractor with calls to… (authored by teemperor).
Herald added a project: LLDB.
Herald added a subscriber: lldb-commits.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D81453/new/

https://reviews.llvm.org/D81453

Files:
  lldb/source/Utility/DataExtractor.cpp


Index: lldb/source/Utility/DataExtractor.cpp
===================================================================
--- lldb/source/Utility/DataExtractor.cpp
+++ 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 @@
   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 @@
   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



Index: lldb/source/Utility/DataExtractor.cpp
===================================================================
--- lldb/source/Utility/DataExtractor.cpp
+++ 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 @@
   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 @@
   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

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