[llvm] [WebAssembly] Implement lowering calls through funcref to call_ref when available (PR #162227)

[Derek Schuff via llvm-commits]

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@@ -0,0 +1,51 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
+; RUN: llc < %s -mattr=+reference-types,-gc | FileCheck --check-prefixes=CHECK,NOGC %s
+; RUN: llc < %s -mattr=+reference-types,+gc | FileCheck --check-prefixes=CHECK,GC %s
+
+; Test that calls through funcref lower to call_ref when GC is available
+
+target triple = "wasm32-unknown-unknown"
+
+%funcref = type ptr addrspace(20);
+
+define void @call_ref_void(%funcref %callee) {
+; CHECK-LABEL: call_ref_void:
+; CHECK:         .functype call_ref_void (funcref) -> ()
+; CHECK-NEXT:  # %bb.0:
+; NOGC-NEXT:     i32.const 0
+; CHECK-NEXT:    local.get 0
+; NOGC-NEXT:     table.set __funcref_call_table
+; NOGC-NEXT:     i32.const 0
+; NOGC-NEXT:     call_indirect __funcref_call_table, () -> ()
+; NOGC-NEXT:     i32.const 0
+; NOGC-NEXT:     ref.null_func
+; NOGC-NEXT:     table.set __funcref_call_table
+; GC-NEXT:       ref.cast () -> ()
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dschuff wrote:

@tlively I assume there is never an advantage to the NOGC version of this compared to the GC version? even if call_indirect is a bit faster than cast+call_ref, it still seems nicer than this dance with the tables.

https://github.com/llvm/llvm-project/pull/162227