[JITLink][AArch32] Implement ELF relocation R_ARM_TARGET1

Prepare a configuration switch and default to R_ARM_ABS32

Author: weliveindetail

llvm/include/llvm/ExecutionEngine/JITLink/aarch32.h

@@ -135,6 +135,8 @@ enum class StubsFlavor {
 struct ArmConfig {
   bool J1J2BranchEncoding = false;
   StubsFlavor Stubs = StubsFlavor::Unsupported;
+  // In the long term, we might want a linker switch like --target1-rel
+  bool Target1Rel = false;
 };
 
 /// Obtain the sub-arch configuration for a given Arm CPU model.

llvm/lib/ExecutionEngine/JITLink/ELF_aarch32.cpp

@@ -31,7 +31,8 @@ namespace llvm {
 namespace jitlink {
 
 /// Translate from ELF relocation type to JITLink-internal edge kind.
-Expected<aarch32::EdgeKind_aarch32> getJITLinkEdgeKind(uint32_t ELFType) {
+Expected<aarch32::EdgeKind_aarch32>
+getJITLinkEdgeKind(uint32_t ELFType, const aarch32::ArmConfig &ArmCfg) {
   switch (ELFType) {
   case ELF::R_ARM_ABS32:
     return aarch32::Data_Pointer32;
@@ -47,6 +48,9 @@ Expected<aarch32::EdgeKind_aarch32> getJITLinkEdgeKind(uint32_t ELFType) {
     return aarch32::Arm_MovwAbsNC;
   case ELF::R_ARM_MOVT_ABS:
     return aarch32::Arm_MovtAbs;
+  case ELF::R_ARM_TARGET1:
+    return (ArmCfg.Target1Rel) ? aarch32::Data_Delta32
+                               : aarch32::Data_Pointer32;
   case ELF::R_ARM_THM_CALL:
     return aarch32::Thumb_Call;
   case ELF::R_ARM_THM_JUMP24:
@@ -171,7 +175,7 @@ class ELFLinkGraphBuilder_aarch32
           inconvertibleErrorCode());
 
     uint32_t Type = Rel.getType(false);
-    Expected<aarch32::EdgeKind_aarch32> Kind = getJITLinkEdgeKind(Type);
+    Expected<aarch32::EdgeKind_aarch32> Kind = getJITLinkEdgeKind(Type, ArmCfg);
     if (!Kind)
       return Kind.takeError();
 

llvm/test/ExecutionEngine/JITLink/AArch32/ELF_relocations_data.s

@@ -29,6 +29,13 @@ rel32:
 	.word target - .
 	.size rel32, .-rel32
 
+# CHECK-TYPE: {{[0-9a-f]+}} R_ARM_TARGET1 target
+# jitlink-check: *{4}(target1_abs32) = target
+	.global target1_abs32
+target1_abs32:
+	.word target(target1)
+	.size	target1_abs32, .-target1_abs32
+
 # CHECK-TYPE: {{[0-9a-f]+}} R_ARM_GOT_PREL target
 #
 # The GOT entry contains the absolute address of the external:

llvm/unittests/ExecutionEngine/JITLink/AArch32Tests.cpp

@@ -39,15 +39,17 @@ struct MutableWord {
 namespace llvm {
 namespace jitlink {
 
-Expected<aarch32::EdgeKind_aarch32> getJITLinkEdgeKind(uint32_t ELFType);
+Expected<aarch32::EdgeKind_aarch32>
+getJITLinkEdgeKind(uint32_t ELFType, const aarch32::ArmConfig &Cfg);
 Expected<uint32_t> getELFRelocationType(Edge::Kind Kind);
 
 } // namespace jitlink
 } // namespace llvm
 
 TEST(AArch32_ELF, EdgeKinds) {
   // Fails: Invalid ELF type -> JITLink kind
-  Expected<uint32_t> ErrKind = getJITLinkEdgeKind(ELF::R_ARM_NONE);
+  aarch32::ArmConfig Cfg;
+  Expected<uint32_t> ErrKind = getJITLinkEdgeKind(ELF::R_ARM_NONE, Cfg);
   EXPECT_TRUE(errorToBool(ErrKind.takeError()));
 
   // Fails: Invalid JITLink kind -> ELF type
@@ -59,7 +61,7 @@ TEST(AArch32_ELF, EdgeKinds) {
     EXPECT_FALSE(errorToBool(ELFType.takeError()))
         << "Failed to translate JITLink kind -> ELF type";
 
-    Expected<Edge::Kind> JITLinkKind = getJITLinkEdgeKind(*ELFType);
+    Expected<Edge::Kind> JITLinkKind = getJITLinkEdgeKind(*ELFType, Cfg);
     EXPECT_FALSE(errorToBool(JITLinkKind.takeError()))
         << "Failed to translate ELF type -> JITLink kind";