[JITLink] Add support for R_X86_64_PC16 relocation type. (#109630)

This patch adds support for R_X86_64_PC16 relocation type and
x86_64::Delta16 edge kind. This patch also adds missing test cases for
R_X86_64_PC32, R_X86_64_PC64 relocation types.

Author: higuoxing

llvm/include/llvm/ExecutionEngine/JITLink/x86_64.h

@@ -95,6 +95,19 @@ enum EdgeKind_x86_64 : Edge::Kind {
   ///
   Delta32,
 
+  /// A 16-bit delta.
+  ///
+  /// Delta from the fixup to the target.
+  ///
+  /// Fixup expression:
+  ///   Fixup <- Target - Fixup + Addend : int16
+  ///
+  /// Errors:
+  ///   - The result of the fixup expression must fit into an int16, otherwise
+  ///     an out-of-range error will be returned.
+  ///
+  Delta16,
+
   /// An 8-bit delta.
   ///
   /// Delta from the fixup to the target.
@@ -486,6 +499,15 @@ inline Error applyFixup(LinkGraph &G, Block &B, const Edge &E,
     break;
   }
 
+  case Delta16: {
+    int64_t Value = E.getTarget().getAddress() - FixupAddress + E.getAddend();
+    if (LLVM_LIKELY(isInt<16>(Value)))
+      *(little16_t *)FixupPtr = Value;
+    else
+      return makeTargetOutOfRangeError(G, B, E);
+    break;
+  }
+
   case Delta8: {
     int64_t Value = E.getTarget().getAddress() - FixupAddress + E.getAddend();
     if (LLVM_LIKELY(isInt<8>(Value)))

llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp

@@ -156,6 +156,9 @@ class ELFLinkGraphBuilder_x86_64 : public ELFLinkGraphBuilder<object::ELF64LE> {
     case ELF::R_X86_64_PC8:
       Kind = x86_64::Delta8;
       break;
+    case ELF::R_X86_64_PC16:
+      Kind = x86_64::Delta16;
+      break;
     case ELF::R_X86_64_PC32:
     case ELF::R_X86_64_GOTPC32:
       Kind = x86_64::Delta32;

llvm/lib/ExecutionEngine/JITLink/x86_64.cpp

@@ -34,6 +34,8 @@ const char *getEdgeKindName(Edge::Kind K) {
     return "Delta64";
   case Delta32:
     return "Delta32";
+  case Delta16:
+    return "Delta16";
   case Delta8:
     return "Delta8";
   case NegDelta64:

llvm/test/ExecutionEngine/JITLink/x86-64/ELF_R_X86_64_PC8.s renamed to llvm/test/ExecutionEngine/JITLink/x86-64/ELF_R_X86_64_PC.s

@@ -2,7 +2,7 @@
 # RUN:     -filetype=obj -o %t.o %s
 # RUN: llvm-jitlink -noexec %t.o
 #
-# Check R_X86_64_PC8 handling.
+# Check R_X86_64_PC* handling.
 
 	.text
 	.globl	main
@@ -14,3 +14,6 @@ main:
 
 	.rodata
 	.byte	main-. # Generate R_X86_64_PC8 relocation.
+	.short	main-. # Generate R_X86_64_PC16 relocation.
+	.long	main-. # Generate R_X86_64_PC32 relocation.
+	.quad	main-. # Generate R_X86_64_PC64 relocation.