[AMDGPU] Fix GFX12 encoding of s_wait_event export_ready (#89622)

As well as flipping the sense of the bit, GFX12 moved it from bit 0 to
bit 1 in the encoded simm16 operand.

(cherry picked from commit e0a763c)

Author: jayfoad

llvm/lib/Target/AMDGPU/SOPInstructions.td

@@ -1786,7 +1786,7 @@ def : GCNPat<
 let SubtargetPredicate = isNotGFX12Plus in
   def : GCNPat <(int_amdgcn_s_wait_event_export_ready), (S_WAIT_EVENT (i16 0))>;
 let SubtargetPredicate = isGFX12Plus in
-  def : GCNPat <(int_amdgcn_s_wait_event_export_ready), (S_WAIT_EVENT (i16 1))>;
+  def : GCNPat <(int_amdgcn_s_wait_event_export_ready), (S_WAIT_EVENT (i16 2))>;
 
 // The first 10 bits of the mode register are the core FP mode on all
 // subtargets.

llvm/test/CodeGen/AMDGPU/llvm.amdgcn.s.wait.event.ll

@@ -5,14 +5,10 @@
 
 ; GCN-LABEL: {{^}}test_wait_event:
 ; GFX11: s_wait_event 0x0
-; GFX12: s_wait_event 0x1
+; GFX12: s_wait_event 0x2
 
-define amdgpu_ps void @test_wait_event() #0 {
+define amdgpu_ps void @test_wait_event() {
 entry:
-  call void @llvm.amdgcn.s.wait.event.export.ready() #0
+  call void @llvm.amdgcn.s.wait.event.export.ready()
   ret void
 }
-
-declare void @llvm.amdgcn.s.wait.event.export.ready() #0
-
-attributes #0 = { nounwind }