From 4b293ebbaa96e75ea5f819e82be284d59ce436ad Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Mon, 31 Mar 2014 17:18:53 +0000
Subject: [PATCH] MS ABI: mangleStringLiteral shouldn't rely on the host's
 endianness

No test case is needed, the one in-tree is sufficient.  The build-bot
never emailed me because something else had upset it.

llvm-svn: 205225
---
 clang/lib/AST/MicrosoftMangle.cpp | 54 ++++++++++++++++++++++---------
 1 file changed, 38 insertions(+), 16 deletions(-)

diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index 7095d2e19780..0fc7d5c8ecc6 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -2385,9 +2385,39 @@ void MicrosoftMangleContextImpl::mangleStringLiteral(const StringLiteral *SL,
     }
   };
 
+  auto GetLittleEndianByte = [&Mangler, &SL](unsigned Index) {
+    unsigned CharByteWidth = SL->getCharByteWidth();
+    uint32_t CodeUnit = SL->getCodeUnit(Index / CharByteWidth);
+    if (CharByteWidth == 1) {
+      return static_cast<char>(CodeUnit);
+    } else if (CharByteWidth == 2) {
+      if (Index % 2)
+        return static_cast<char>((CodeUnit >> 8) & 0xff);
+      else
+        return static_cast<char>(CodeUnit & 0xff);
+    } else {
+      llvm_unreachable("unsupported CharByteWidth");
+    }
+  };
+
+  auto GetBigEndianByte = [&Mangler, &SL](unsigned Index) {
+    unsigned CharByteWidth = SL->getCharByteWidth();
+    uint32_t CodeUnit = SL->getCodeUnit(Index / CharByteWidth);
+    if (CharByteWidth == 1) {
+      return static_cast<char>(CodeUnit);
+    } else if (CharByteWidth == 2) {
+      if (Index % 2)
+        return static_cast<char>(CodeUnit & 0xff);
+      else
+        return static_cast<char>((CodeUnit >> 8) & 0xff);
+    } else {
+      llvm_unreachable("unsupported CharByteWidth");
+    }
+  };
+
   // CRC all the bytes of the StringLiteral.
-  for (char Byte : SL->getBytes())
-    UpdateCRC(Byte);
+  for (unsigned I = 0, E = SL->getByteLength(); I != E; ++I)
+    UpdateCRC(GetLittleEndianByte(I));
 
   // The NUL terminator byte(s) were not present earlier,
   // we need to manually process those bytes into the CRC.
@@ -2462,25 +2492,17 @@ void MicrosoftMangleContextImpl::mangleStringLiteral(const StringLiteral *SL,
     }
   };
 
-  auto MangleChar = [&Mangler, &MangleByte, &SL](uint32_t CodeUnit) {
-    if (SL->getCharByteWidth() == 1) {
-      MangleByte(static_cast<char>(CodeUnit));
-    } else if (SL->getCharByteWidth() == 2) {
-      MangleByte(static_cast<char>((CodeUnit >> 16) & 0xff));
-      MangleByte(static_cast<char>(CodeUnit & 0xff));
-    } else {
-      llvm_unreachable("unsupported CharByteWidth");
-    }
-  };
-
   // Enforce our 32 character max.
   unsigned NumCharsToMangle = std::min(32U, SL->getLength());
-  for (unsigned i = 0; i < NumCharsToMangle; ++i)
-    MangleChar(SL->getCodeUnit(i));
+  for (unsigned I = 0, E = NumCharsToMangle * SL->getCharByteWidth(); I != E;
+       ++I)
+    MangleByte(GetBigEndianByte(I));
 
   // Encode the NUL terminator if there is room.
   if (NumCharsToMangle < 32)
-    MangleChar(0);
+    for (unsigned NullTerminator = 0; NullTerminator < SL->getCharByteWidth();
+         ++NullTerminator)
+      MangleByte(0);
 
   Mangler.getStream() << '@';
 }
-- 
2.34.1