Reland "Lower `@llvm.global_dtors` using `__cxa_atexit` on MachO"

For MachO, lower `@llvm.global_dtors` into `@llvm_global_ctors` with
`__cxa_atexit` calls to avoid emitting the deprecated `__mod_term_func`.

Reuse the existing `WebAssemblyLowerGlobalDtors.cpp` to accomplish this.

Enable fallback to the old behavior via Clang driver flag
(`-fregister-global-dtors-with-atexit`) or llc / code generation flag
(`-lower-global-dtors-via-cxa-atexit`).  This escape hatch will be
removed in the future.

Differential Revision: https://reviews.llvm.org/D121736

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index 85014b6..cd3b06b 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -25,6 +25,7 @@
 #include "llvm/CodeGen/RegAllocRegistry.h"
 #include "llvm/CodeGen/TargetPassConfig.h"
 #include "llvm/IR/Function.h"
+#include "llvm/InitializePasses.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/TargetRegistry.h"
 #include "llvm/Target/TargetOptions.h"
@@ -56,7 +57,7 @@ extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeWebAssemblyTarget() {
   auto &PR = *PassRegistry::getPassRegistry();
   initializeWebAssemblyAddMissingPrototypesPass(PR);
   initializeWebAssemblyLowerEmscriptenEHSjLjPass(PR);
-  initializeLowerGlobalDtorsPass(PR);
+  initializeLowerGlobalDtorsLegacyPassPass(PR);
   initializeFixFunctionBitcastsPass(PR);
   initializeOptimizeReturnedPass(PR);
   initializeWebAssemblyArgumentMovePass(PR);
@@ -412,7 +413,7 @@ void WebAssemblyPassConfig::addIRPasses() {
   addPass(createWebAssemblyAddMissingPrototypes());
 
   // Lower .llvm.global_dtors into .llvm_global_ctors with __cxa_atexit calls.
-  addPass(createWebAssemblyLowerGlobalDtors());
+  addPass(createLowerGlobalDtorsLegacyPass());
 
   // Fix function bitcasts, as WebAssembly requires caller and callee signatures
   // to match.