MicroMIPS specific little endian fixup data byte ordering.
Differential Revision: http://llvm-reviews.chandlerc.com/D3245
llvm-svn: 205528
diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
index 541f8b6..0f99ecc 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
@@ -112,6 +112,22 @@
MCELFObjectTargetWriter::getOSABI(OSType), IsLittle, Is64Bit);
}
+// Little-endian fixup data byte ordering:
+// mips32r2: a | b | x | x
+// microMIPS: x | x | a | b
+
+static bool needsMMLEByteOrder(unsigned Kind) {
+ return Kind >= Mips::fixup_MICROMIPS_26_S1 &&
+ Kind < Mips::LastTargetFixupKind;
+}
+
+// Calculate index for microMIPS specific little endian byte order
+static unsigned calculateMMLEIndex(unsigned i) {
+ assert(i <= 3 && "Index out of range!");
+
+ return (1 - i / 2) * 2 + i % 2;
+}
+
/// ApplyFixup - Apply the \p Value for given \p Fixup into the provided
/// data fragment, at the offset specified by the fixup and following the
/// fixup kind as appropriate.
@@ -149,8 +165,12 @@
// Grab current value, if any, from bits.
uint64_t CurVal = 0;
+ bool microMipsLEByteOrder = needsMMLEByteOrder((unsigned) Kind);
+
for (unsigned i = 0; i != NumBytes; ++i) {
- unsigned Idx = IsLittle ? i : (FullSize - 1 - i);
+ unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i)
+ : i)
+ : (FullSize - 1 - i);
CurVal |= (uint64_t)((uint8_t)Data[Offset + Idx]) << (i*8);
}
@@ -160,7 +180,9 @@
// Write out the fixed up bytes back to the code/data bits.
for (unsigned i = 0; i != NumBytes; ++i) {
- unsigned Idx = IsLittle ? i : (FullSize - 1 - i);
+ unsigned Idx = IsLittle ? (microMipsLEByteOrder ? calculateMMLEIndex(i)
+ : i)
+ : (FullSize - 1 - i);
Data[Offset + Idx] = (uint8_t)((CurVal >> (i*8)) & 0xff);
}
}