Merging r277504:

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r277504 | nhaehnle | 2016-08-02 12:31:14 -0700 (Tue, 02 Aug 2016) | 21 lines

AMDGPU: Stay in WQM for non-intrinsic stores

Summary:
Two types of stores are possible in pixel shaders: stores to memory that are
explicitly requested at the API level, and stores that are an implementation
detail of register spilling or lowering of arrays.

For the first kind of store, we must ensure that helper pixels have no effect
and hence WQM must be disabled. The second kind of store must always be
executed, because the written value may be loaded again in a way that is
relevant for helper pixels as well -- and there are no externally visible
effects anyway.

This is a candidate for the 3.9 release branch.

Reviewers: arsenm, tstellarAMD, mareko

Subscribers: arsenm, kzhuravl, llvm-commits

Differential Revision: https://reviews.llvm.org/D22675

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llvm-svn: 288104

1 files changed, 41 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/AMDGPU/wqm.ll b/llvm/test/CodeGen/AMDGPU/wqm.ll
index b272190..809a7ba 100644
--- a/llvm/test/CodeGen/AMDGPU/wqm.ll
+++ b/llvm/test/CodeGen/AMDGPU/wqm.ll
@@ -374,6 +374,47 @@ break:
   ret <4 x float> %c.iv
 }
 
+; Only intrinsic stores need exact execution -- other stores do not have
+; externally visible effects and may require WQM for correctness.
+;
+; CHECK-LABEL: {{^}}test_alloca:
+; CHECK: s_mov_b64 [[LIVE:s\[[0-9]+:[0-9]+\]]], exec
+; CHECK: s_wqm_b64 exec, exec
+
+; CHECK: s_and_b64 exec, exec, [[LIVE]]
+; CHECK: buffer_store_dword {{v[0-9]+}}, off, {{s\[[0-9]+:[0-9]+\]}}, 0
+; CHECK: s_wqm_b64 exec, exec
+; CHECK: buffer_store_dword {{v[0-9]+}}, {{v[0-9]+}}, {{s\[[0-9]+:[0-9]+\]}}, {{s[0-9]+}} offen
+; CHECK: s_and_b64 exec, exec, [[LIVE]]
+; CHECK: buffer_store_dword {{v[0-9]+}}, {{v[0-9]+}}, {{s\[[0-9]+:[0-9]+\]}}, 0 idxen
+; CHECK: s_wqm_b64 exec, exec
+; CHECK: buffer_load_dword {{v[0-9]+}}, {{v[0-9]+}}, {{s\[[0-9]+:[0-9]+\]}}, {{s[0-9]+}} offen
+
+; CHECK: image_sample
+; CHECK: s_and_b64 exec, exec, [[LIVE]]
+; CHECK: buffer_store_dwordx4
+define amdgpu_ps void @test_alloca(float %data, i32 %a, i32 %idx) nounwind {
+entry:
+  %array = alloca [32 x i32], align 4
+
+  call void @llvm.amdgcn.buffer.store.f32(float %data, <4 x i32> undef, i32 0, i32 0, i1 0, i1 0)
+
+  %s.gep = getelementptr [32 x i32], [32 x i32]* %array, i32 0, i32 0
+  store volatile i32 %a, i32* %s.gep, align 4
+
+  call void @llvm.amdgcn.buffer.store.f32(float %data, <4 x i32> undef, i32 1, i32 0, i1 0, i1 0)
+
+  %c.gep = getelementptr [32 x i32], [32 x i32]* %array, i32 0, i32 %idx
+  %c = load i32, i32* %c.gep, align 4
+
+  %t = call <4 x float> @llvm.SI.image.sample.i32(i32 %c, <8 x i32> undef, <4 x i32> undef, i32 15, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0)
+
+  call void @llvm.amdgcn.buffer.store.v4f32(<4 x float> %t, <4 x i32> undef, i32 0, i32 0, i1 0, i1 0)
+
+  ret void
+}
+
+
 declare void @llvm.amdgcn.image.store.v4i32(<4 x float>, <4 x i32>, <8 x i32>, i32, i1, i1, i1, i1) #1
 declare void @llvm.amdgcn.buffer.store.f32(float, <4 x i32>, i32, i32, i1, i1) #1
 declare void @llvm.amdgcn.buffer.store.v4f32(<4 x float>, <4 x i32>, i32, i32, i1, i1) #1