[C-API] LLVMOrcCreateObjectLinkingLayerWithInProcessMemoryManager (#169862)

Allow C programs to use JITLink with trivial new C-API wrapper. Modeled
on `LLVMOrcCreateRTDyldObjectLinkingLayerWithSectionMemoryManager`
except that it has to deal with failure of
`jitlink::InProcessMemoryManager::Create()`. Function name suggested by
@lhames in #106203.

I suppose failure of underlying platform-specific things like
`sysconf(_SC_PAGESIZE)` shouldn't really happen. An alternative error
reporting style might be to follow
`LLVMOrcCreateDynamicLibrarySearchGeneratorForProcess` and return
`LLVMErrorRef` with an output parameter for the `LLVMOrcObjectLayerRef`,
but then it wouldn't be a drop-in replacement for
`LLVMOrcCreateRTDyldObjectLinkingLayerWithSectionMemoryManager`.
Thoughts?

This is wanted by PostgreSQL (branch using this API:
https://github.com/macdice/postgres/tree/llvm-22-proposed-c-api). (We're
also using `LLVMCreatePerfJITEventListener`,
`LLVMCreatePerfJITEventListener`,
`LLVMOrcRTDyldObjectLinkingLayerRegisterJITEventListener`, so it looks
like we'll need to research `PerfSupportPlugin`,
`DebuggerSupportPlugin`, `ObjectLinkingLayer::addPlugin()`...)

Author: macdice

llvm/include/llvm-c/OrcEE.h

@@ -43,6 +43,14 @@ typedef void (*LLVMMemoryManagerNotifyTerminatingCallback)(void *CtxCtx);
  * @{
  */
 
+/**
+ * Create a ObjectLinkingLayer instance using the standard JITLink
+ * InProcessMemoryManager for memory management.
+ */
+LLVM_C_ABI LLVMErrorRef
+LLVMOrcCreateObjectLinkingLayerWithInProcessMemoryManager(
+    LLVMOrcObjectLayerRef *Result, LLVMOrcExecutionSessionRef ES);
+
 /**
  * Create a RTDyldObjectLinkingLayer instance using the standard
  * SectionMemoryManager for memory management.

llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp

@@ -11,9 +11,11 @@
 #include "llvm-c/OrcEE.h"
 #include "llvm-c/TargetMachine.h"
 
+#include "llvm/ExecutionEngine/JITLink/JITLinkMemoryManager.h"
 #include "llvm/ExecutionEngine/Orc/AbsoluteSymbols.h"
 #include "llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h"
 #include "llvm/ExecutionEngine/Orc/LLJIT.h"
+#include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
 #include "llvm/ExecutionEngine/Orc/ObjectTransformLayer.h"
 #include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
@@ -1017,6 +1019,17 @@ LLVMOrcLLJITGetObjTransformLayer(LLVMOrcLLJITRef J) {
   return wrap(&unwrap(J)->getObjTransformLayer());
 }
 
+LLVMErrorRef LLVMOrcCreateObjectLinkingLayerWithInProcessMemoryManager(
+    LLVMOrcObjectLayerRef *Result, LLVMOrcExecutionSessionRef ES) {
+  assert(Result && "Result must not be null");
+  assert(ES && "ES must not be null");
+  auto MM = jitlink::InProcessMemoryManager::Create();
+  if (!MM)
+    return wrap(MM.takeError());
+  *Result = wrap(new ObjectLinkingLayer(*unwrap(ES), std::move(*MM)));
+  return LLVMErrorSuccess;
+}
+
 LLVMOrcObjectLayerRef
 LLVMOrcCreateRTDyldObjectLinkingLayerWithSectionMemoryManager(
     LLVMOrcExecutionSessionRef ES) {