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llvm-mirror/test/CodeGen/AMDGPU/llvm.amdgcn.s.barrier.ll
Jay Foad 7c4d297102 [AMDGPU] Mark s_barrier as having side effects but not accessing memory. 
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
2019-09-06 10:07:28 +00:00

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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -march=amdgcn -verify-machineinstrs < %s | FileCheck --check-prefixes=GCN,GFX8,VARIANT0 %s
; RUN: llc -march=amdgcn -mattr=+auto-waitcnt-before-barrier -verify-machineinstrs < %s | FileCheck --check-prefixes=GCN,GFX8,VARIANT1 %s
; RUN: llc -march=amdgcn -mcpu=gfx900 -verify-machineinstrs < %s | FileCheck --check-prefixes=GCN,GFX9,VARIANT2 %s
; RUN: llc -march=amdgcn -mcpu=gfx900 -mattr=+auto-waitcnt-before-barrier -verify-machineinstrs < %s | FileCheck --check-prefixes=GCN,GFX9,VARIANT3 %s
define amdgpu_kernel void @test_barrier(i32 addrspace(1)* %out, i32 %size) #0 {
; VARIANT0-LABEL: test_barrier:
; VARIANT0: ; %bb.0: ; %entry
; VARIANT0-NEXT: s_load_dwordx2 s[4:5], s[0:1], 0x9
; VARIANT0-NEXT: s_load_dword s2, s[0:1], 0xb
; VARIANT0-NEXT: v_not_b32_e32 v3, v0
; VARIANT0-NEXT: s_mov_b32 s7, 0xf000
; VARIANT0-NEXT: s_mov_b32 s6, 0
; VARIANT0-NEXT: v_lshlrev_b32_e32 v1, 2, v0
; VARIANT0-NEXT: v_mov_b32_e32 v2, 0
; VARIANT0-NEXT: s_waitcnt lgkmcnt(0)
; VARIANT0-NEXT: buffer_store_dword v0, v[1:2], s[4:7], 0 addr64
; VARIANT0-NEXT: s_waitcnt vmcnt(0) expcnt(0)
; VARIANT0-NEXT: s_barrier
; VARIANT0-NEXT: v_add_i32_e32 v3, vcc, s2, v3
; VARIANT0-NEXT: v_ashrrev_i32_e32 v4, 31, v3
; VARIANT0-NEXT: v_lshl_b64 v[3:4], v[3:4], 2
; VARIANT0-NEXT: buffer_load_dword v0, v[3:4], s[4:7], 0 addr64
; VARIANT0-NEXT: s_waitcnt vmcnt(0)
; VARIANT0-NEXT: buffer_store_dword v0, v[1:2], s[4:7], 0 addr64
; VARIANT0-NEXT: s_endpgm
;
; VARIANT1-LABEL: test_barrier:
; VARIANT1: ; %bb.0: ; %entry
; VARIANT1-NEXT: s_load_dwordx2 s[4:5], s[0:1], 0x9
; VARIANT1-NEXT: s_load_dword s2, s[0:1], 0xb
; VARIANT1-NEXT: v_not_b32_e32 v3, v0
; VARIANT1-NEXT: s_mov_b32 s7, 0xf000
; VARIANT1-NEXT: s_mov_b32 s6, 0
; VARIANT1-NEXT: v_lshlrev_b32_e32 v1, 2, v0
; VARIANT1-NEXT: v_mov_b32_e32 v2, 0
; VARIANT1-NEXT: s_waitcnt lgkmcnt(0)
; VARIANT1-NEXT: buffer_store_dword v0, v[1:2], s[4:7], 0 addr64
; VARIANT1-NEXT: s_barrier
; VARIANT1-NEXT: v_add_i32_e32 v3, vcc, s2, v3
; VARIANT1-NEXT: v_ashrrev_i32_e32 v4, 31, v3
; VARIANT1-NEXT: v_lshl_b64 v[3:4], v[3:4], 2
; VARIANT1-NEXT: s_waitcnt expcnt(0)
; VARIANT1-NEXT: buffer_load_dword v0, v[3:4], s[4:7], 0 addr64
; VARIANT1-NEXT: s_waitcnt vmcnt(0)
; VARIANT1-NEXT: buffer_store_dword v0, v[1:2], s[4:7], 0 addr64
; VARIANT1-NEXT: s_endpgm
;
; VARIANT2-LABEL: test_barrier:
; VARIANT2: ; %bb.0: ; %entry
; VARIANT2-NEXT: s_load_dwordx2 s[2:3], s[0:1], 0x24
; VARIANT2-NEXT: s_load_dword s0, s[0:1], 0x2c
; VARIANT2-NEXT: v_lshlrev_b32_e32 v3, 2, v0
; VARIANT2-NEXT: s_waitcnt lgkmcnt(0)
; VARIANT2-NEXT: v_mov_b32_e32 v4, s3
; VARIANT2-NEXT: v_xad_u32 v1, v0, -1, s0
; VARIANT2-NEXT: v_ashrrev_i32_e32 v2, 31, v1
; VARIANT2-NEXT: v_add_co_u32_e32 v3, vcc, s2, v3
; VARIANT2-NEXT: v_lshlrev_b64 v[1:2], 2, v[1:2]
; VARIANT2-NEXT: v_addc_co_u32_e32 v4, vcc, 0, v4, vcc
; VARIANT2-NEXT: global_store_dword v[3:4], v0, off
; VARIANT2-NEXT: v_mov_b32_e32 v5, s3
; VARIANT2-NEXT: v_add_co_u32_e32 v0, vcc, s2, v1
; VARIANT2-NEXT: v_addc_co_u32_e32 v1, vcc, v5, v2, vcc
; VARIANT2-NEXT: s_waitcnt vmcnt(0)
; VARIANT2-NEXT: s_barrier
; VARIANT2-NEXT: global_load_dword v0, v[0:1], off
; VARIANT2-NEXT: s_waitcnt vmcnt(0)
; VARIANT2-NEXT: global_store_dword v[3:4], v0, off
; VARIANT2-NEXT: s_endpgm
;
; VARIANT3-LABEL: test_barrier:
; VARIANT3: ; %bb.0: ; %entry
; VARIANT3-NEXT: s_load_dwordx2 s[2:3], s[0:1], 0x24
; VARIANT3-NEXT: s_load_dword s0, s[0:1], 0x2c
; VARIANT3-NEXT: v_lshlrev_b32_e32 v3, 2, v0
; VARIANT3-NEXT: s_waitcnt lgkmcnt(0)
; VARIANT3-NEXT: v_mov_b32_e32 v4, s3
; VARIANT3-NEXT: v_xad_u32 v1, v0, -1, s0
; VARIANT3-NEXT: v_ashrrev_i32_e32 v2, 31, v1
; VARIANT3-NEXT: v_add_co_u32_e32 v3, vcc, s2, v3
; VARIANT3-NEXT: v_lshlrev_b64 v[1:2], 2, v[1:2]
; VARIANT3-NEXT: v_addc_co_u32_e32 v4, vcc, 0, v4, vcc
; VARIANT3-NEXT: global_store_dword v[3:4], v0, off
; VARIANT3-NEXT: v_mov_b32_e32 v5, s3
; VARIANT3-NEXT: v_add_co_u32_e32 v0, vcc, s2, v1
; VARIANT3-NEXT: v_addc_co_u32_e32 v1, vcc, v5, v2, vcc
; VARIANT3-NEXT: s_barrier
; VARIANT3-NEXT: global_load_dword v0, v[0:1], off
; VARIANT3-NEXT: s_waitcnt vmcnt(0)
; VARIANT3-NEXT: global_store_dword v[3:4], v0, off
; VARIANT3-NEXT: s_endpgm
entry:
%tmp = call i32 @llvm.amdgcn.workitem.id.x()
%tmp1 = getelementptr i32, i32 addrspace(1)* %out, i32 %tmp
store i32 %tmp, i32 addrspace(1)* %tmp1
call void @llvm.amdgcn.s.barrier()
%tmp3 = sub i32 %size, 1
%tmp4 = sub i32 %tmp3, %tmp
%tmp5 = getelementptr i32, i32 addrspace(1)* %out, i32 %tmp4
%tmp6 = load i32, i32 addrspace(1)* %tmp5
store i32 %tmp6, i32 addrspace(1)* %tmp1
ret void
}
declare void @llvm.amdgcn.s.barrier() #1
declare i32 @llvm.amdgcn.workitem.id.x() #2
attributes #0 = { nounwind }
attributes #1 = { convergent nounwind }
attributes #2 = { nounwind readnone }
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