[PATCH] D22389: AMDGPU: Fix not expanding control flow after some kill blocks

[Matt Arsenault via llvm-commits]

arsenm created this revision.
arsenm added a reviewer: tstellarAMD.
arsenm added a subscriber: llvm-commits.
Herald added subscribers: kzhuravl, arsenm.

    Also stop trying to insert skip blocks at end_cf. This
    was inserting them at the end of the block which doesn't make
    sense. The skip should be inserted at the beginning of the block
    right after the end cf. Just remove this for now since no tests
    seem to stress this and I think this can be handled more generally
    later.
    
    Fixes bug 28550


https://reviews.llvm.org/D22389

Files:
  lib/Target/AMDGPU/SILowerControlFlow.cpp
  test/CodeGen/AMDGPU/skip-if-dead.ll

Index: test/CodeGen/AMDGPU/skip-if-dead.ll
===================================================================
--- test/CodeGen/AMDGPU/skip-if-dead.ll
+++ test/CodeGen/AMDGPU/skip-if-dead.ll
@@ -336,6 +336,55 @@
   ret void
 }
 
+; CHECK-LABEL: {{^}}if_after_kill_block:
+; CHECK: ; BB#0:
+; CHECK: s_and_saveexec_b64
+; CHECK: s_xor_b64
+; CHECK-NEXT: mask branch [[BB4:BB[0-9]+_[0-9]+]]
+
+; CHECK: v_cmpx_le_f32_e32 vcc, 0,
+; CHECK: [[BB4]]:
+; CHECK: s_or_b64 exec, exec
+; CHECK: image_sample_c
+
+; CHECK: v_cmp_neq_f32_e32 vcc, 0,
+; CHECK: s_and_b64 exec, exec,
+; CHECK: s_and_saveexec_b64 s{{\[[0-9]+:[0-9]+\]}}, vcc
+; CHECK: s_xor_b64 s{{\[[0-9]+:[0-9]+\]}}, exec
+; CHECK: mask branch [[END:BB[0-9]+_[0-9]+]]
+; CHECK-NOT: branch
+
+; CHECK: ; BB#3: ; %bb8
+; CHECK: buffer_store_dword
+
+; CHECK: [[END]]:
+; CHECK: s_or_b64 exec, exec
+; CHECK: s_endpgm
+define amdgpu_ps void @if_after_kill_block(float %arg, float %arg1, <4 x i32> %arg2) #0 {
+bb:
+  %tmp = fcmp ult float %arg1, 0.000000e+00
+  br i1 %tmp, label %bb3, label %bb4
+
+bb3:                                              ; preds = %bb
+  call void @llvm.AMDGPU.kill(float %arg)
+  br label %bb4
+
+bb4:                                              ; preds = %bb3, %bb
+  %tmp5 = call <4 x float> @llvm.SI.image.sample.c.v4i32(<4 x i32> %arg2, <8 x i32> undef, <4 x i32> undef, i32 15, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0)
+  %tmp6 = extractelement <4 x float> %tmp5, i32 0
+  %tmp7 = fcmp une float %tmp6, 0.000000e+00
+  br i1 %tmp7, label %bb8, label %bb9
+
+bb8:                                              ; preds = %bb9, %bb4
+  store volatile i32 9, i32 addrspace(1)* undef
+  ret void
+
+bb9:                                              ; preds = %bb4
+  ret void
+}
+
 declare void @llvm.AMDGPU.kill(float) #0
+declare <4 x float> @llvm.SI.image.sample.c.v4i32(<4 x i32>, <8 x i32>, <4 x i32>, i32, i32, i32, i32, i32, i32, i32, i32) #1
 
 attributes #0 = { nounwind }
+attributes #1 = { nounwind readnone }
\ No newline at end of file
Index: lib/Target/AMDGPU/SILowerControlFlow.cpp
===================================================================
--- lib/Target/AMDGPU/SILowerControlFlow.cpp
+++ lib/Target/AMDGPU/SILowerControlFlow.cpp
@@ -748,22 +748,17 @@
         case AMDGPU::SI_END_CF:
           if (--Depth == 0 && HaveKill) {
             HaveKill = false;
-
-            if (skipIfDead(MI, *NextBB)) {
-              NextBB = std::next(BI);
-              BE = MF.end();
-              Next = MBB.end();
-            }
+            // TODO: Insert skip if exec is 0?
           }
+
           EndCf(MI);
           break;
 
         case AMDGPU::SI_KILL_TERMINATOR:
           if (Depth == 0) {
             if (skipIfDead(MI, *NextBB)) {
               NextBB = std::next(BI);
               BE = MF.end();
-              Next = MBB.end();
             }
           } else
             HaveKill = true;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D22389.64065.patch
Type: text/x-patch
Size: 2922 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20160714/699a7be7/attachment.bin>