Incremental big endian patch by Jack Carter.

These changes allow us to compile big endian from the command line for 32 bit
Mips targets. This patch will result in code and data actually being produced
in the correct endianess.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153153 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 27 insertions, 10 deletions

diff --git a/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp b/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
index d69570bdf0..7f5c3775b0 100644
--- a/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
+++ b/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
@@ -92,25 +92,42 @@ public:
     if (!Value)
       return; // Doesn't change encoding.
 
+    // Where do we start in the object
     unsigned Offset = Fixup.getOffset();
-    // FIXME: The below code will not work across endian models
-    // How many bytes/bits are we fixing up?
-    unsigned NumBytes = ((getFixupKindInfo(Kind).TargetSize-1)/8)+1;
-    uint64_t Mask = ((uint64_t)1 << getFixupKindInfo(Kind).TargetSize) - 1;
+    // Number of bytes we need to fixup
+    unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8;
+    // Used to point to big endian bytes
+    unsigned FullSize;
+
+    switch (Kind) {
+    case Mips::fixup_Mips_16:
+      FullSize = 2;
+      break;
+    case Mips::fixup_Mips_64:
+      FullSize = 8;
+      break;
+    default:
+      FullSize = 4;
+      break;
+    }
 
     // Grab current value, if any, from bits.
     uint64_t CurVal = 0;
-    for (unsigned i = 0; i != NumBytes; ++i)
-      CurVal |= ((uint8_t)Data[Offset + i]) << (i * 8);
 
+    for (unsigned i = 0; i != NumBytes; ++i) {
+      unsigned Idx = IsLittle ? i : (FullSize - 1 - i);
+      CurVal |= (uint64_t)((uint8_t)Data[Offset + Idx]) << (i*8);
+    }
+
+    uint64_t Mask = ((uint64_t)(-1) >> (64 - getFixupKindInfo(Kind).TargetSize));
     CurVal = (CurVal & ~Mask) | ((CurVal + Value) & Mask);
 
-    // Write out the bytes back to the code/data bits.
-    // First the unaffected bits and then the fixup.
+    // Write out the fixed up bytes back to the code/data bits.
     for (unsigned i = 0; i != NumBytes; ++i) {
-      Data[Offset + i] = uint8_t((CurVal >> (i * 8)) & 0xff);
+      unsigned Idx = IsLittle ? i : (FullSize - 1 - i);
+      Data[Offset + Idx] = (uint8_t)((CurVal >> (i*8)) & 0xff);
     }
-}
+  }
 
   unsigned getNumFixupKinds() const { return Mips::NumTargetFixupKinds; }