VLDR fixups need special handling under Thumb. While the encoding is the same,

the order of the bytes in the data stream is flipped around.

llvm-svn: 121215

3 files changed, 23 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/ARMAsmBackend.cpp
index 96a5548134b..7c4823d8ba4 100644
--- a/llvm/lib/Target/ARM/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmBackend.cpp
@@ -115,6 +115,7 @@ static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
     Binary = ((Binary & 0x7ff) << 16) | (Binary >> 11);
     return Binary;
   }
+  case ARM::fixup_t2_pcrel_10:
   case ARM::fixup_arm_pcrel_10: {
     // Offset by 8 just as above.
     Value = Value - 8;
@@ -127,6 +128,16 @@ static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
     Value >>= 2;
     assert ((Value < 256) && "Out of range pc-relative fixup value!");
     Value |= isAdd << 23;
+    
+    // Same addressing mode as fixup_arm_pcrel_10, but with the bytes reordered.
+    if (Kind == ARM::fixup_t2_pcrel_10) {
+      uint64_t swapped = (Value & 0x00FF0000) >> 16;
+      swapped |= (Value & 0xFF000000) >> 16;
+      swapped |= (Value & 0x000000FF) << 16;
+      swapped |= (Value & 0x0000FF00) << 16;
+      return swapped;
+    }
+    
     return Value;
   }
   }
@@ -218,6 +229,7 @@ static unsigned getFixupKindNumBytes(unsigned Kind) {
   case ARM::fixup_arm_adr_pcrel_12:
   case ARM::fixup_arm_branch:
     return 3;
+  case ARM::fixup_t2_pcrel_10:
   case ARM::fixup_arm_thumb_bl:
     return 4;
   }
diff --git a/llvm/lib/Target/ARM/ARMFixupKinds.h b/llvm/lib/Target/ARM/ARMFixupKinds.h
index c905611906f..0136e0c004f 100644
--- a/llvm/lib/Target/ARM/ARMFixupKinds.h
+++ b/llvm/lib/Target/ARM/ARMFixupKinds.h
@@ -19,9 +19,12 @@ enum Fixups {
   // addresses
   fixup_arm_ldst_pcrel_12 = FirstTargetFixupKind,
   // fixup_arm_pcrel_10 - 10-bit PC relative relocation for symbol addresses
-  // used in VFP and Thumb2 instructions where the lower 2 bits are not encoded
+  // used in VFP instructions where the lower 2 bits are not encoded
   // (so it's encoded as an 8-bit immediate).
   fixup_arm_pcrel_10,
+  // fixup_t2_pcrel_10 - Equivalent to fixup_arm_pcrel_10, accounting for
+  // the byteswapped encoding of Thumb2 instructions.
+  fixup_t2_pcrel_10,
   // fixup_arm_adr_pcrel_12 - 12-bit PC relative relocation for the ADR
   // instruction.
   fixup_arm_adr_pcrel_12,
diff --git a/llvm/lib/Target/ARM/ARMMCCodeEmitter.cpp b/llvm/lib/Target/ARM/ARMMCCodeEmitter.cpp
index 229e00e65d4..ba1f6d30ca2 100644
--- a/llvm/lib/Target/ARM/ARMMCCodeEmitter.cpp
+++ b/llvm/lib/Target/ARM/ARMMCCodeEmitter.cpp
@@ -48,6 +48,7 @@ public:
       // name                       off   bits  flags
       { "fixup_arm_ldst_pcrel_12",  1,    24,   MCFixupKindInfo::FKF_IsPCRel },
       { "fixup_arm_pcrel_10",       1,    24,   MCFixupKindInfo::FKF_IsPCRel },
+      { "fixup_t2_pcrel_10",        0,    32,   MCFixupKindInfo::FKF_IsPCRel },
       { "fixup_arm_adr_pcrel_12",   1,    24,   MCFixupKindInfo::FKF_IsPCRel },
       { "fixup_arm_branch",         1,    24,   MCFixupKindInfo::FKF_IsPCRel },
       { "fixup_arm_thumb_bl",       0,    32,   MCFixupKindInfo::FKF_IsPCRel },
@@ -737,7 +738,12 @@ getAddrMode5OpValue(const MCInst &MI, unsigned OpIdx,
 
     assert(MO.isExpr() && "Unexpected machine operand type!");
     const MCExpr *Expr = MO.getExpr();
-    MCFixupKind Kind = MCFixupKind(ARM::fixup_arm_pcrel_10);
+    MCFixupKind Kind;
+    const ARMSubtarget &Subtarget = TM.getSubtarget<ARMSubtarget>();
+    if (Subtarget.isThumb2())
+      Kind = MCFixupKind(ARM::fixup_t2_pcrel_10);
+    else
+      Kind = MCFixupKind(ARM::fixup_arm_pcrel_10);
     Fixups.push_back(MCFixup::Create(0, Expr, Kind));
 
     ++MCNumCPRelocations;