[WebAssembly] Use RefTypeMem2Local instead of Mem2Reg (#83196)

When reference-types feature is enabled, forcing mem2reg unconditionally
even in `-O0` has some problems described in #81575. This uses
RefTypeMem2Local pass added in #81965 instead. This also removes
`IsForced` parameter added in

https://github.com/llvm/llvm-project/commit/890146b19206827bc48ee1ae1dc1534ff2ff18d7
given that we don't need it anymore.

This may still hurt debug info related to reference type variables a
little during the backend transformation given that they are not stored
in memory anymore, but reference type variables are presumably rare and
it would be still a lot less damage than forcing mem2reg on the whole
program. Also this fixes the EH problem described in #81575.

Fixes #81575.

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index 4d4cae1..70685b2 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -478,8 +478,9 @@ void WebAssemblyPassConfig::addISelPrepare() {
       WasmTM->getSubtargetImpl(std::string(WasmTM->getTargetCPU()),
                                std::string(WasmTM->getTargetFeatureString()));
   if (Subtarget->hasReferenceTypes()) {
-    // We need to remove allocas for reference types
-    addPass(createPromoteMemoryToRegisterPass(true));
+    // We need to move reference type allocas to WASM_ADDRESS_SPACE_VAR so that
+    // loads and stores are promoted to local.gets/local.sets.
+    addPass(createWebAssemblyRefTypeMem2Local());
   }
   // Lower atomics and TLS if necessary
   addPass(new CoalesceFeaturesAndStripAtomics(&getWebAssemblyTargetMachine()));