Implement .rel relocation for R_ARM_ABS32 in MCJIT.

Patch by Amara Emerson.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165128 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 26 insertions, 2 deletions

diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
index 597c5cb131..efefacf632 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -264,14 +264,19 @@ void RuntimeDyldELF::resolveARMRelocation(uint8_t *LocalAddress,
   default:
     llvm_unreachable("Not implemented relocation type!");
 
-  // Just write 32bit value to relocation address
+  // Write a 32bit value to relocation address, taking into account the 
+  // implicit addend encoded in the target.
   case ELF::R_ARM_ABS32 :
-    *TargetPtr = Value;
+    *TargetPtr += Value;
     break;
 
   // Write first 16 bit of 32 bit value to the mov instruction.
   // Last 4 bit should be shifted.
   case ELF::R_ARM_MOVW_ABS_NC :
+    // We are not expecting any other addend in the relocation address.
+    // Using 0x000F0FFF because MOVW has its 16 bit immediate split into 2 
+    // non-contiguous fields.
+    assert((*TargetPtr & 0x000F0FFF) == 0);
     Value = Value & 0xFFFF;
     *TargetPtr |= Value & 0xFFF;
     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
@@ -280,6 +285,9 @@ void RuntimeDyldELF::resolveARMRelocation(uint8_t *LocalAddress,
   // Write last 16 bit of 32 bit value to the mov instruction.
   // Last 4 bit should be shifted.
   case ELF::R_ARM_MOVT_ABS :
+    // We are not expecting any other addend in the relocation address.
+    // Use 0x000F0FFF for the same reason as R_ARM_MOVW_ABS_NC.
+    assert((*TargetPtr & 0x000F0FFF) == 0);
     Value = (Value >> 16) & 0xFFFF;
     *TargetPtr |= Value & 0xFFF;
     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
diff --git a/test/ExecutionEngine/MCJIT/test-ptr-reloc.ll b/test/ExecutionEngine/MCJIT/test-ptr-reloc.ll
new file mode 100644
index 0000000000..93b6a6deff
--- /dev/null
+++ b/test/ExecutionEngine/MCJIT/test-ptr-reloc.ll
@@ -0,0 +1,16 @@
+; RUN: %lli -mtriple=%mcjit_triple -use-mcjit -O0 %s
+
+@.str = private unnamed_addr constant [6 x i8] c"data1\00", align 1
+@ptr = global i8* getelementptr inbounds ([6 x i8]* @.str, i32 0, i32 0), align 4
+@.str1 = private unnamed_addr constant [6 x i8] c"data2\00", align 1
+@ptr2 = global i8* getelementptr inbounds ([6 x i8]* @.str1, i32 0, i32 0), align 4
+
+define i32 @main(i32 %argc, i8** nocapture %argv) nounwind readonly {
+entry:
+  %0 = load i8** @ptr, align 4
+  %1 = load i8** @ptr2, align 4
+  %cmp = icmp eq i8* %0, %1
+  %. = zext i1 %cmp to i32
+  ret i32 %.
+}
+