AMDGPU/SI: Do not generate s_waitcnt after ds_permute/ds_bpermute

Changpeng Fang · Changpeng Fang · commit 234fcb81d3e4 · 2016-03-17T16:43:50.000Z
Symmary: ds_permute/ds_bpermute do not read memory so s_waitcnt is not needed. Reviewers arsenm, tstellarAMD Subscribers llvm-commits, arsenm Differential Revision: http://reviews.llvm.org/D18197 llvm-svn: 263720
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.td b/llvm/lib/Target/AMDGPU/SIInstrInfo.td
@@ -2519,7 +2519,7 @@ multiclass DS_1A1D_PERMUTE <bits<8> op, string opName, RegisterClass rc,
   dag ins = (ins VGPR_32:$addr, rc:$data0),
   string asm = opName#" $vdst, $addr, $data0"> {
 
-  let mayLoad = 0, mayStore = 0, isConvergent = 1 in {
+  let LGKM_CNT = 0, mayLoad = 0, mayStore = 0, isConvergent = 1 in {
     def "" : DS_Pseudo <opName, outs, ins,
      [(set (i32 rc:$vdst),
          (node (i32 VGPR_32:$addr), (i32 rc:$data0)))]>;
diff --git a/llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.bpermute.ll b/llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.bpermute.ll
@@ -10,4 +10,28 @@ define void @ds_bpermute(i32 addrspace(1)* %out, i32 %index, i32 %src) nounwind
   ret void
 }
 
+; FUNC-LABEL: {{^}}bpermute_no_waitcnt_test:
+; CHECK: s_cbranch_scc1
+; CHECK: ds_bpermute_b32 v{{[0-9]+}}, v{{[0-9]+}}, v{{[0-9]+}}
+; CHECK-NOT: s_waitcnt
+define void @bpermute_no_waitcnt_test(i32 addrspace(1)* %out, i32 %cond) {
+entry:
+
+  %tmp = icmp eq i32 %cond, 0
+  br i1 %tmp, label %if, label %else
+
+if:                                               ; preds = %entry
+
+  %bpermute = call i32 @llvm.amdgcn.ds.bpermute(i32 0, i32 0) #0
+  br label %endif
+
+else:                                             ; preds = %entry
+  br label %endif
+
+endif:
+  %val = phi i32 [ %bpermute, %if ], [0, %else]      ; preds = %else, %if
+  store i32 %val, i32 addrspace(1)* %out, align 4
+  ret void
+}
+
 attributes #0 = { nounwind readnone convergent }
diff --git a/llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.permute.ll b/llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.permute.ll
@@ -5,9 +5,33 @@ declare i32 @llvm.amdgcn.ds.permute(i32, i32) #0
 ; FUNC-LABEL: {{^}}ds_permute:
 ; CHECK: ds_permute_b32 v{{[0-9]+}}, v{{[0-9]+}}, v{{[0-9]+}}
 define void @ds_permute(i32 addrspace(1)* %out, i32 %index, i32 %src) nounwind {
-  %bpermute = call i32 @llvm.amdgcn.ds.permute(i32 %index, i32 %src) #0
-  store i32 %bpermute, i32 addrspace(1)* %out, align 4
+  %permute = call i32 @llvm.amdgcn.ds.permute(i32 %index, i32 %src) #0
+  store i32 %permute, i32 addrspace(1)* %out, align 4
   ret void
 }
 
+; FUNC-LABEL: {{^}}permute_no_waitcnt_test:
+; CHECK: s_cbranch_scc1
+; CHECK: ds_permute_b32 v{{[0-9]+}}, v{{[0-9]+}}, v{{[0-9]+}}
+; CHECK-NOT: s_waitcnt
+define void @permute_no_waitcnt_test(i32 addrspace(1)* %out, i32 %cond) {
+entry:
+
+  %tmp = icmp eq i32 %cond, 0
+  br i1 %tmp, label %if, label %else
+
+if:                                               ; preds = %entry
+  %permute = call i32 @llvm.amdgcn.ds.permute(i32 0, i32 0) #0
+  br label %endif
+
+else:                                             ; preds = %entry
+  br label %endif
+
+endif:
+  %val = phi i32 [ %permute, %if ], [0, %else]      ; preds = %else, %if
+  store i32 %val, i32 addrspace(1)* %out, align 4
+  ret void
+}
+
+
 attributes #0 = { nounwind readnone convergent }
