This patch handles unaligned loads and stores in Mips JIT. Mips backend

implements unaligned loads and stores with assembler macro-instructions
ulw, usw, ulh, ulhu, ush, and this patch emits corresponding instructions
instead of these macros. Since each unaligned load/store is expanded
into two corresponding loads/stores where offset for second load/store is
modified by +3 (for words) or +1 (for halfwords).

Patch by Petar Jovanovic and Sasa Stankovic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144081 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 2 deletions

diff --git a/lib/Target/Mips/MipsJITInfo.cpp b/lib/Target/Mips/MipsJITInfo.cpp
index e3f6a75..a0ee722 100644
--- a/lib/Target/Mips/MipsJITInfo.cpp
+++ b/lib/Target/Mips/MipsJITInfo.cpp
@@ -218,10 +218,16 @@ void MipsJITInfo::relocate(void *Function, MachineRelocation *MR,
       *((unsigned*) RelocPos) |= (unsigned) ResultPtr;
       break;
 
-    case Mips::reloc_mips_lo:
-      ResultPtr = ResultPtr & 0xffff;
+    case Mips::reloc_mips_lo: {
+      // Addend is needed for unaligned load/store instructions, where offset
+      // for the second load/store in the expanded instruction sequence must
+      // be modified by +1 or +3. Otherwise, Addend is 0.
+      int Addend = *((unsigned*) RelocPos) & 0xffff;
+      ResultPtr = (ResultPtr + Addend) & 0xffff;
+      *((unsigned*) RelocPos) &= 0xffff0000;
       *((unsigned*) RelocPos) |= (unsigned) ResultPtr;
       break;
+    }
 
     default:
       llvm_unreachable("ERROR: Unknown Mips relocation.");