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7c4d297102
Summary: This fixes poor scheduling in a function containing a barrier and a few load instructions. Without this fix, ScheduleDAGInstrs::buildSchedGraph adds an artificial edge in the dependency graph from the barrier instruction to the exit node representing live-out latency, with a latency of about 500 cycles. Because of this it thinks the critical path through the graph also has a latency of about 500 cycles. And because of that it does not think that any of the load instructions are on the critical path, so it schedules them with no regard for their (80 cycle) latency, which gives poor results. Reviewers: arsenm, dstuttard, tpr, nhaehnle Subscribers: kzhuravl, jvesely, wdng, yaxunl, t-tye, hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D67218 llvm-svn: 371192
81 lines
3.5 KiB
LLVM
81 lines
3.5 KiB
LLVM
; RUN: llc -march=amdgcn -mcpu=verde -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=GCN %s
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; RUN: llc -march=amdgcn -mcpu=bonaire -verify-machineinstrs < %s | FileCheck -check-prefix=CI -check-prefix=GCN %s
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@local_memory.local_mem = internal unnamed_addr addrspace(3) global [128 x i32] undef, align 4
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; GCN-LABEL: {{^}}local_memory:
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; GCN-NOT: s_wqm_b64
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; GCN: ds_write_b32
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; GCN: s_barrier
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; GCN: ds_read_b32 {{v[0-9]+}},
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define amdgpu_kernel void @local_memory(i32 addrspace(1)* %out) #0 {
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entry:
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%y.i = call i32 @llvm.amdgcn.workitem.id.x() #1
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%arrayidx = getelementptr inbounds [128 x i32], [128 x i32] addrspace(3)* @local_memory.local_mem, i32 0, i32 %y.i
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store i32 %y.i, i32 addrspace(3)* %arrayidx, align 4
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%add = add nsw i32 %y.i, 1
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%cmp = icmp eq i32 %add, 16
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%.add = select i1 %cmp, i32 0, i32 %add
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call void @llvm.amdgcn.s.barrier()
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%arrayidx1 = getelementptr inbounds [128 x i32], [128 x i32] addrspace(3)* @local_memory.local_mem, i32 0, i32 %.add
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%tmp = load i32, i32 addrspace(3)* %arrayidx1, align 4
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%arrayidx2 = getelementptr inbounds i32, i32 addrspace(1)* %out, i32 %y.i
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store i32 %tmp, i32 addrspace(1)* %arrayidx2, align 4
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ret void
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}
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@local_memory_two_objects.local_mem0 = internal unnamed_addr addrspace(3) global [4 x i32] undef, align 4
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@local_memory_two_objects.local_mem1 = internal unnamed_addr addrspace(3) global [4 x i32] undef, align 4
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; Check that the LDS size emitted correctly
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; EG: .long 166120
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; EG-NEXT: .long 8
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; GCN: .long 47180
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; GCN-NEXT: .long 32900
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; GCN-LABEL: {{^}}local_memory_two_objects:
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; GCN: v_lshlrev_b32_e32 [[ADDRW:v[0-9]+]], 2, v0
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; CI-DAG: v_sub_i32_e32 [[SUB:v[0-9]+]], vcc, 0, [[ADDRW]]
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; CI-DAG: ds_write2_b32 [[ADDRW]], {{v[0-9]+}}, {{v[0-9]+}} offset1:4
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; SI-DAG: ds_write2_b32 [[ADDRW]], {{v[0-9]+}}, {{v[0-9]+}} offset1:4
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; SI-DAG: v_sub_i32_e32 [[SUB0:v[0-9]+]], vcc, 28, [[ADDRW]]
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; SI-DAG: v_sub_i32_e32 [[SUB1:v[0-9]+]], vcc, 12, [[ADDRW]]
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; GCN: s_barrier
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; SI-DAG: ds_read_b32 v{{[0-9]+}}, [[SUB0]]
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; SI-DAG: ds_read_b32 v{{[0-9]+}}, [[SUB1]]
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; CI: ds_read2_b32 {{v\[[0-9]+:[0-9]+\]}}, [[SUB]] offset0:3 offset1:7
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define amdgpu_kernel void @local_memory_two_objects(i32 addrspace(1)* %out) #0 {
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entry:
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%x.i = call i32 @llvm.amdgcn.workitem.id.x()
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%arrayidx = getelementptr inbounds [4 x i32], [4 x i32] addrspace(3)* @local_memory_two_objects.local_mem0, i32 0, i32 %x.i
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store i32 %x.i, i32 addrspace(3)* %arrayidx, align 4
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%mul = shl nsw i32 %x.i, 1
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%arrayidx1 = getelementptr inbounds [4 x i32], [4 x i32] addrspace(3)* @local_memory_two_objects.local_mem1, i32 0, i32 %x.i
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store i32 %mul, i32 addrspace(3)* %arrayidx1, align 4
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%sub = sub nsw i32 3, %x.i
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call void @llvm.amdgcn.s.barrier()
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%arrayidx2 = getelementptr inbounds [4 x i32], [4 x i32] addrspace(3)* @local_memory_two_objects.local_mem0, i32 0, i32 %sub
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%tmp = load i32, i32 addrspace(3)* %arrayidx2, align 4
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%arrayidx3 = getelementptr inbounds i32, i32 addrspace(1)* %out, i32 %x.i
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store i32 %tmp, i32 addrspace(1)* %arrayidx3, align 4
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%arrayidx4 = getelementptr inbounds [4 x i32], [4 x i32] addrspace(3)* @local_memory_two_objects.local_mem1, i32 0, i32 %sub
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%tmp1 = load i32, i32 addrspace(3)* %arrayidx4, align 4
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%add = add nsw i32 %x.i, 4
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%arrayidx5 = getelementptr inbounds i32, i32 addrspace(1)* %out, i32 %add
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store i32 %tmp1, i32 addrspace(1)* %arrayidx5, align 4
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ret void
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}
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declare i32 @llvm.amdgcn.workitem.id.x() #1
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declare void @llvm.amdgcn.s.barrier() #2
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attributes #0 = { nounwind }
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attributes #1 = { nounwind readnone }
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attributes #2 = { convergent nounwind }
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