[Orc] Move delta-handling for trampoline sizes into the resolver block.

This is the first step towards adding a target-independent callback
handler API.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233049 91177308-0d34-0410-b5e6-96231b3b80d8

lib/ExecutionEngine/Orc/OrcTargetSupport.cpp

@@ -53,6 +53,7 @@ const char* OrcX86_64::ResolverBlockName = "orc_resolver_block";
 
 void OrcX86_64::insertResolverBlock(
     Module &M, JITCompileCallbackManagerBase<OrcX86_64> &JCBM) {
+  const unsigned X86_64_TrampolineLength = 6;
   auto CallbackPtr = executeCompileCallback<OrcX86_64>;
   uint64_t CallbackAddr =
       static_cast<uint64_t>(reinterpret_cast<uintptr_t>(CallbackPtr));
@@ -77,6 +78,7 @@ void OrcX86_64::insertResolverBlock(
   AsmStream << "  leaq    jit_callback_manager_addr(%rip), %rdi\n"
             << "  movq    (%rdi), %rdi\n"
             << "  movq    " << ReturnAddrOffset << "(%rsp), %rsi\n"
+            << "  subq    $" << X86_64_TrampolineLength << ", %rsi\n"
             << "  movabsq $" << CallbackAddr << ", %rax\n"
             << "  callq   *%rax\n"
             << "  movq    %rax, " << ReturnAddrOffset << "(%rsp)\n";