[llvm] [AMDGPU] Mark WAIT_ASYNCMARK as zero-size instruction (PR #195107)

[Zhewen Yu via llvm-commits]

https://github.com/Yu-Zhewen created https://github.com/llvm/llvm-project/pull/195107

`WAIT_ASYNCMARK` emits no bytes but was inheriting `Size = 4` from `SOPP_Pseudo`.

Without the fix, #194362 causes: `Size mismatch for: WAIT_ASYNCMARK 1 Expected exact size: 4 Actual size: 0`

>From f527cdc7bcef239423f6485fadb0bd33e8edb030 Mon Sep 17 00:00:00 2001
From: Yu-Zhewen <zhewenyu at amd.com>
Date: Thu, 30 Apr 2026 15:15:29 +0000
Subject: [PATCH] zero size

Signed-off-by: Yu-Zhewen <zhewenyu at amd.com>
---
 llvm/lib/Target/AMDGPU/SOPInstructions.td | 1 +
 1 file changed, 1 insertion(+)

diff --git a/llvm/lib/Target/AMDGPU/SOPInstructions.td b/llvm/lib/Target/AMDGPU/SOPInstructions.td
index eb7ad8bcb04ce..e0bdcf61440f3 100644
--- a/llvm/lib/Target/AMDGPU/SOPInstructions.td
+++ b/llvm/lib/Target/AMDGPU/SOPInstructions.td
@@ -1736,6 +1736,7 @@ def ASYNCMARK : SPseudoInstSI<(outs), (ins),
 def WAIT_ASYNCMARK : SOPP_Pseudo <"", (ins s16imm:$simm16), "$simm16",
     [(int_amdgcn_wait_asyncmark timm:$simm16)]> {
     let maybeAtomic = 0;
+    let Size = 0;
     let isMeta = 1;
 }
 }