39bf765bb6
For most targets, the register class comes from the type so this makes no difference. For AMDGPU, the selected register class depends on the divergence of the value. For a constant phi input, this will always be false. The heuristic for whether to treat the value as a scalar or vector constant based on the uses would then incorrectly think this is a scalar use, when really the phi is a copy from S to V. This avoids an intermediate s_mov_b32 plus a copy in some cases. These would often, but not always, fold out in mi passes. This only adjusts the constant input case. It may make sense to do this for the non-constant case as well.
282 lines
12 KiB
LLVM
282 lines
12 KiB
LLVM
; RUN: llc -O0 -mtriple=amdgcn--amdhsa -amdgpu-spill-sgpr-to-vgpr=0 -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefix=VMEM -check-prefix=GCN %s
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; RUN: llc -O0 -mtriple=amdgcn--amdhsa -amdgpu-spill-sgpr-to-vgpr=1 -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefix=VGPR -check-prefix=GCN %s
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; Verify registers used for tracking exec mask changes when all
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; registers are spilled at the end of the block. The SGPR spill
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; placement relative to the exec modifications are important.
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; FIXME: This checks with SGPR to VGPR spilling disabled, but this may
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; not work correctly in cases where no workitems take a branch.
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; GCN-LABEL: {{^}}divergent_if_endif:
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; GCN: {{^}}; %bb.0:
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; GCN: s_mov_b32 m0, -1
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; GCN: ds_read_b32 [[LOAD0:v[0-9]+]]
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; Spill load
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; GCN: buffer_store_dword [[LOAD0]], off, s[0:3], 0 offset:[[LOAD0_OFFSET:[0-9]+]] ; 4-byte Folded Spill
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; GCN: v_cmp_eq_u32_e64 [[CMP0:s\[[0-9]+:[0-9]\]]], v{{[0-9]+}}, v{{[0-9]+}}
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; Spill saved exec
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; GCN: s_mov_b64 s[[[SAVEEXEC_LO:[0-9]+]]:[[SAVEEXEC_HI:[0-9]+]]], exec
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; VGPR: v_writelane_b32 [[SPILL_VGPR:v[0-9]+]], s[[SAVEEXEC_LO]], [[SAVEEXEC_LO_LANE:[0-9]+]]
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; VGPR: v_writelane_b32 [[SPILL_VGPR]], s[[SAVEEXEC_HI]], [[SAVEEXEC_HI_LANE:[0-9]+]]
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; VMEM: v_writelane_b32 v[[V_SAVEEXEC:[0-9]+]], s[[SAVEEXEC_LO]], 0
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; VMEM: v_writelane_b32 v[[V_SAVEEXEC]], s[[SAVEEXEC_HI]], 1
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; VMEM: buffer_store_dword v[[V_SAVEEXEC]], off, s[0:3], 0 ; 4-byte Folded Spill
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; GCN: s_and_b64 s[[[ANDEXEC_LO:[0-9]+]]:[[ANDEXEC_HI:[0-9]+]]], s[[[SAVEEXEC_LO]]:[[SAVEEXEC_HI]]], [[CMP0]]
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; GCN: s_mov_b64 exec, s[[[ANDEXEC_LO]]:[[ANDEXEC_HI]]]
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; GCN: s_cbranch_execz [[ENDIF:.LBB[0-9]+_[0-9]+]]
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; GCN: ; %bb.{{[0-9]+}}: ; %if
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; GCN: buffer_load_dword [[RELOAD_LOAD0:v[0-9]+]], off, s[0:3], 0 offset:[[LOAD0_OFFSET]] ; 4-byte Folded Reload
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; GCN: s_mov_b32 m0, -1
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; GCN: ds_read_b32 [[LOAD1:v[0-9]+]]
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; GCN: s_waitcnt vmcnt(0) lgkmcnt(0)
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; Spill val register
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; GCN: v_add_i32_e32 [[VAL:v[0-9]+]], vcc, [[RELOAD_LOAD0]], [[LOAD1]]
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; GCN: buffer_store_dword [[VAL]], off, s[0:3], 0 offset:[[VAL_OFFSET:[0-9]+]] ; 4-byte Folded Spill
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; VMEM: [[ENDIF]]:
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; Reload and restore exec mask
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; VGPR: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_LO:[0-9]+]], [[SPILL_VGPR]], [[SAVEEXEC_LO_LANE]]
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; VGPR: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_HI:[0-9]+]], [[SPILL_VGPR]], [[SAVEEXEC_HI_LANE]]
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; VMEM: buffer_load_dword v[[V_RELOAD_SAVEEXEC:[0-9]+]], off, s[0:3], 0 ; 4-byte Folded Reload
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; VMEM: s_waitcnt vmcnt(0)
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; VMEM: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_LO:[0-9]+]], v[[V_RELOAD_SAVEEXEC]], 0
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; VMEM: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_HI:[0-9]+]], v[[V_RELOAD_SAVEEXEC]], 1
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; GCN: s_or_b64 exec, exec, s[[[S_RELOAD_SAVEEXEC_LO]]:[[S_RELOAD_SAVEEXEC_HI]]]
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; Restore val
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; GCN: buffer_load_dword [[RELOAD_VAL:v[0-9]+]], off, s[0:3], 0 offset:[[VAL_OFFSET]] ; 4-byte Folded Reload
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; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RELOAD_VAL]]
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; VGPR: .amdhsa_private_segment_fixed_size 16
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define amdgpu_kernel void @divergent_if_endif(ptr addrspace(1) %out) #0 {
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entry:
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%tid = call i32 @llvm.amdgcn.workitem.id.x()
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%load0 = load volatile i32, ptr addrspace(3) undef
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%cmp0 = icmp eq i32 %tid, 0
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br i1 %cmp0, label %if, label %endif
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if:
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%load1 = load volatile i32, ptr addrspace(3) undef
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%val = add i32 %load0, %load1
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br label %endif
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endif:
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%tmp4 = phi i32 [ %val, %if ], [ 0, %entry ]
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store i32 %tmp4, ptr addrspace(1) %out
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ret void
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}
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; GCN-LABEL: {{^}}divergent_loop:
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; GCN: {{^}}; %bb.0:
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; GCN-DAG: s_mov_b32 m0, -1
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; GCN-DAG: v_mov_b32_e32 [[PTR0:v[0-9]+]], 0{{$}}
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; GCN: ds_read_b32 [[LOAD0:v[0-9]+]], [[PTR0]]
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; GCN: v_cmp_eq_u32_e64 [[CMP0:s\[[0-9]+:[0-9]+\]]], v{{[0-9]+}}, s{{[0-9]+}}
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; Spill load
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; GCN: buffer_store_dword [[LOAD0]], off, s[0:3], 0 offset:[[LOAD0_OFFSET:[0-9]+]] ; 4-byte Folded Spill
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; GCN: s_mov_b64 s[[[SAVEEXEC_LO:[0-9]+]]:[[SAVEEXEC_HI:[0-9]+]]], exec
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; Spill saved exec
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; VGPR: v_writelane_b32 [[SPILL_VGPR:v[0-9]+]], s[[SAVEEXEC_LO]], [[SAVEEXEC_LO_LANE:[0-9]+]]
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; VGPR: v_writelane_b32 [[SPILL_VGPR]], s[[SAVEEXEC_HI]], [[SAVEEXEC_HI_LANE:[0-9]+]]
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; VMEM: v_writelane_b32 v[[V_SAVEEXEC:[0-9]+]], s[[SAVEEXEC_LO]], 0
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; VMEM: v_writelane_b32 v[[V_SAVEEXEC]], s[[SAVEEXEC_HI]], 1
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; VMEM: buffer_store_dword v[[V_SAVEEXEC]], off, s[0:3], 0 ; 4-byte Folded Spill
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; GCN: s_and_b64 s[[[ANDEXEC_LO:[0-9]+]]:[[ANDEXEC_HI:[0-9]+]]], s[[[SAVEEXEC_LO:[0-9]+]]:[[SAVEEXEC_HI:[0-9]+]]], [[CMP0]]
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; GCN: s_mov_b64 exec, s[[[ANDEXEC_LO]]:[[ANDEXEC_HI]]]
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; GCN-NEXT: s_cbranch_execz [[END:.LBB[0-9]+_[0-9]+]]
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; GCN: [[LOOP:.LBB[0-9]+_[0-9]+]]:
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; GCN: buffer_load_dword v[[VAL_LOOP_RELOAD:[0-9]+]], off, s[0:3], 0 offset:[[LOAD0_OFFSET]] ; 4-byte Folded Reload
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; GCN: v_sub_i32_e32 v[[VAL_LOOP_RELOAD]], vcc, v[[VAL_LOOP_RELOAD]], v{{[0-9]+}}
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; GCN: s_cmp_lg_u32
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; VMEM: buffer_store_dword
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; VMEM: buffer_store_dword
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; VMEM: buffer_store_dword
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; GCN: buffer_store_dword v[[VAL_LOOP_RELOAD]], off, s[0:3], 0 offset:{{[0-9]+}} ; 4-byte Folded Spill
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; GCN-NEXT: s_cbranch_scc1 [[LOOP]]
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; GCN: buffer_store_dword v[[VAL_LOOP_RELOAD]], off, s[0:3], 0 offset:[[VAL_SUB_OFFSET:[0-9]+]] ; 4-byte Folded Spill
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; GCN: [[END]]:
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; VGPR: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_LO:[0-9]+]], [[SPILL_VGPR]], [[SAVEEXEC_LO_LANE]]
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; VGPR: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_HI:[0-9]+]], [[SPILL_VGPR]], [[SAVEEXEC_HI_LANE]]
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; VMEM: buffer_load_dword v[[V_RELOAD_SAVEEXEC:[0-9]+]], off, s[0:3], 0 ; 4-byte Folded Reload
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; VMEM: s_waitcnt vmcnt(0)
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; VMEM: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_LO:[0-9]+]], v[[V_RELOAD_SAVEEXEC]], 0
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; VMEM: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_HI:[0-9]+]], v[[V_RELOAD_SAVEEXEC]], 1
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; GCN: s_or_b64 exec, exec, s[[[S_RELOAD_SAVEEXEC_LO]]:[[S_RELOAD_SAVEEXEC_HI]]]
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; GCN: buffer_load_dword v[[VAL_END:[0-9]+]], off, s[0:3], 0 offset:[[VAL_SUB_OFFSET]] ; 4-byte Folded Reload
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; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, v[[VAL_END]]
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; VGPR: .amdhsa_private_segment_fixed_size 20
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define amdgpu_kernel void @divergent_loop(ptr addrspace(1) %out) #0 {
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entry:
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%tid = call i32 @llvm.amdgcn.workitem.id.x()
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%load0 = load volatile i32, ptr addrspace(3) null
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%cmp0 = icmp eq i32 %tid, 0
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br i1 %cmp0, label %loop, label %end
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loop:
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%i = phi i32 [ %i.inc, %loop ], [ 0, %entry ]
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%val = phi i32 [ %val.sub, %loop ], [ %load0, %entry ]
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%load1 = load volatile i32, ptr addrspace(3) undef
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%i.inc = add i32 %i, 1
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%val.sub = sub i32 %val, %load1
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%cmp1 = icmp ne i32 %i, 256
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br i1 %cmp1, label %loop, label %end
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end:
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%tmp4 = phi i32 [ %val.sub, %loop ], [ 0, %entry ]
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store i32 %tmp4, ptr addrspace(1) %out
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ret void
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}
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; GCN-LABEL: {{^}}divergent_if_else_endif:
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; GCN: {{^}}; %bb.0:
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; GCN-DAG: s_mov_b32 m0, -1
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; GCN-DAG: v_mov_b32_e32 [[PTR0:v[0-9]+]], 0{{$}}
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; GCN: ds_read_b32 [[LOAD0:v[0-9]+]], [[PTR0]]
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; Spill load
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; GCN: buffer_store_dword [[LOAD0]], off, s[0:3], 0 offset:[[LOAD0_OFFSET:[0-9]+]] ; 4-byte Folded Spill
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; GCN: s_mov_b32 [[ZERO:s[0-9]+]], 0
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; GCN: v_cmp_ne_u32_e64 [[CMP0:s\[[0-9]+:[0-9]\]]], v{{[0-9]+}}, [[ZERO]]
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; GCN: s_mov_b64 s[[[SAVEEXEC_LO:[0-9]+]]:[[SAVEEXEC_HI:[0-9]+]]], exec
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; GCN: s_and_b64 s[[[ANDEXEC_LO:[0-9]+]]:[[ANDEXEC_HI:[0-9]+]]], s[[[SAVEEXEC_LO:[0-9]+]]:[[SAVEEXEC_HI:[0-9]+]]], [[CMP0]]
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; GCN: s_xor_b64 s[[[SAVEEXEC_LO]]:[[SAVEEXEC_HI]]], s[[[ANDEXEC_LO]]:[[ANDEXEC_HI]]], s[[[SAVEEXEC_LO]]:[[SAVEEXEC_HI]]]
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; Spill saved exec
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; VGPR: v_writelane_b32 [[SPILL_VGPR:v[0-9]+]], s[[SAVEEXEC_LO]], [[SAVEEXEC_LO_LANE:[0-9]+]]
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; VGPR: v_writelane_b32 [[SPILL_VGPR]], s[[SAVEEXEC_HI]], [[SAVEEXEC_HI_LANE:[0-9]+]]
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; VGPR: buffer_store_dword [[SPILL_VGPR]], off, s[0:3], 0 ; 4-byte Folded Spill
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; VMEM: v_writelane_b32 v[[V_SAVEEXEC:[0-9]+]], s[[SAVEEXEC_LO]], 0
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; VMEM: v_writelane_b32 v[[V_SAVEEXEC]], s[[SAVEEXEC_HI]], 1
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; VMEM: buffer_store_dword v[[V_SAVEEXEC]], off, s[0:3], 0 ; 4-byte Folded Spill
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; GCN: s_mov_b64 exec, [[CMP0]]
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; FIXME: It makes no sense to put this skip here
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; GCN: s_cbranch_execz [[FLOW:.LBB[0-9]+_[0-9]+]]
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; GCN-NEXT: s_branch [[ELSE:.LBB[0-9]+_[0-9]+]]
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; GCN: [[FLOW]]: ; %Flow
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; VGPR: buffer_load_dword [[SPILL_VGPR:v[0-9]+]], off, s[0:3], 0 ; 4-byte Folded Reload
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; VGPR: v_readlane_b32 s[[FLOW_S_RELOAD_SAVEEXEC_LO:[0-9]+]], [[SPILL_VGPR]], [[SAVEEXEC_LO_LANE]]
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; VGPR: v_readlane_b32 s[[FLOW_S_RELOAD_SAVEEXEC_HI:[0-9]+]], [[SPILL_VGPR]], [[SAVEEXEC_HI_LANE]]
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; VMEM: buffer_load_dword v[[FLOW_V_RELOAD_SAVEEXEC:[0-9]+]], off, s[0:3], 0
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; VMEM: s_waitcnt vmcnt(0)
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; VMEM: v_readlane_b32 s[[FLOW_S_RELOAD_SAVEEXEC_LO:[0-9]+]], v[[FLOW_V_RELOAD_SAVEEXEC]], 0
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; VMEM: v_readlane_b32 s[[FLOW_S_RELOAD_SAVEEXEC_HI:[0-9]+]], v[[FLOW_V_RELOAD_SAVEEXEC]], 1
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; GCN: s_or_saveexec_b64 s[[[FLOW_S_RELOAD_SAVEEXEC_LO_SAVEEXEC:[0-9]+]]:[[FLOW_S_RELOAD_SAVEEXEC_HI_SAVEEXEC:[0-9]+]]], s[[[FLOW_S_RELOAD_SAVEEXEC_LO]]:[[FLOW_S_RELOAD_SAVEEXEC_HI]]]
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; GCN: buffer_load_dword [[FLOW_VAL:v[0-9]+]], off, s[0:3], 0 offset:[[FLOW_VAL_OFFSET:[0-9]+]] ; 4-byte Folded Reload
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; Regular spill value restored after exec modification
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; Followed by spill
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; GCN: buffer_store_dword [[FLOW_VAL]], off, s[0:3], 0 offset:[[RESULT_OFFSET:[0-9]+]] ; 4-byte Folded Spill
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; GCN: s_and_b64 s[[[FLOW_AND_EXEC_LO:[0-9]+]]:[[FLOW_AND_EXEC_HI:[0-9]+]]], exec, s[[[FLOW_S_RELOAD_SAVEEXEC_LO_SAVEEXEC]]:[[FLOW_S_RELOAD_SAVEEXEC_HI_SAVEEXEC]]]
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; Spill saved exec
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; VGPR: v_writelane_b32 [[SPILL_VGPR]], s[[FLOW_AND_EXEC_LO]], [[FLOW_SAVEEXEC_LO_LANE:[0-9]+]]
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; VGPR: v_writelane_b32 [[SPILL_VGPR]], s[[FLOW_AND_EXEC_HI]], [[FLOW_SAVEEXEC_HI_LANE:[0-9]+]]
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; VMEM: v_writelane_b32 v[[FLOW_V_SAVEEXEC:[0-9]+]], s[[FLOW_AND_EXEC_LO]], 0
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; VMEM: v_writelane_b32 v[[FLOW_V_SAVEEXEC]], s[[FLOW_AND_EXEC_HI]], 1
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; VMEM: buffer_store_dword v[[FLOW_V_SAVEEXEC]], off, s[0:3], 0 offset:[[FLOW_SAVEEXEC_OFFSET:[0-9]+]] ; 4-byte Folded Spill
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; GCN: s_xor_b64 exec, exec, s[[[FLOW_AND_EXEC_LO]]:[[FLOW_AND_EXEC_HI]]]
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; GCN-NEXT: s_cbranch_execz [[ENDIF:.LBB[0-9]+_[0-9]+]]
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; GCN: ; %bb.{{[0-9]+}}: ; %if
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; GCN: buffer_load_dword v[[LOAD0_RELOAD:[0-9]+]], off, s[0:3], 0 offset:[[LOAD0_OFFSET]] ; 4-byte Folded Reload
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; GCN: ds_read_b32
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; GCN: v_add_i32_e32 v[[LOAD0_RELOAD]], vcc, v[[LOAD0_RELOAD]], [[ADD:v[0-9]+]]
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; GCN: buffer_store_dword v[[LOAD0_RELOAD]], off, s[0:3], 0 offset:[[RESULT_OFFSET]] ; 4-byte Folded Spill
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; GCN-NEXT: s_branch [[ENDIF:.LBB[0-9]+_[0-9]+]]
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; GCN: [[ELSE]]: ; %else
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; GCN: buffer_load_dword v[[LOAD0_RELOAD:[0-9]+]], off, s[0:3], 0 offset:[[LOAD0_OFFSET]] ; 4-byte Folded Reload
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; GCN: v_sub_i32_e32 v[[LOAD0_RELOAD]], vcc, v[[LOAD0_RELOAD]], v{{[0-9]+}}
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; GCN: buffer_store_dword v[[LOAD0_RELOAD]], off, s[0:3], 0 offset:[[FLOW_RESULT_OFFSET:[0-9]+]] ; 4-byte Folded Spill
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; GCN-NEXT: s_branch [[FLOW]]
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; GCN: [[ENDIF]]:
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; VGPR: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_LO:[0-9]+]], [[SPILL_VGPR]], [[FLOW_SAVEEXEC_LO_LANE]]
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; VGPR: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_HI:[0-9]+]], [[SPILL_VGPR]], [[FLOW_SAVEEXEC_HI_LANE]]
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; VMEM: buffer_load_dword v[[V_RELOAD_SAVEEXEC:[0-9]+]], off, s[0:3], 0 offset:[[FLOW_SAVEEXEC_OFFSET]] ; 4-byte Folded Reload
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; VMEM: s_waitcnt vmcnt(0)
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; VMEM: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_LO:[0-9]+]], v[[V_RELOAD_SAVEEXEC]], 0
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; VMEM: v_readlane_b32 s[[S_RELOAD_SAVEEXEC_HI:[0-9]+]], v[[V_RELOAD_SAVEEXEC]], 1
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; GCN: s_or_b64 exec, exec, s[[[S_RELOAD_SAVEEXEC_LO]]:[[S_RELOAD_SAVEEXEC_HI]]]
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; GCN: buffer_load_dword v[[RESULT:[0-9]+]], off, s[0:3], 0 offset:[[RESULT_OFFSET]] ; 4-byte Folded Reload
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; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, v[[RESULT]]
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define amdgpu_kernel void @divergent_if_else_endif(ptr addrspace(1) %out) #0 {
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entry:
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%tid = call i32 @llvm.amdgcn.workitem.id.x()
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%load0 = load volatile i32, ptr addrspace(3) null
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%cmp0 = icmp eq i32 %tid, 0
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br i1 %cmp0, label %if, label %else
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if:
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%load1 = load volatile i32, ptr addrspace(3) undef
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%val0 = add i32 %load0, %load1
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br label %endif
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else:
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%load2 = load volatile i32, ptr addrspace(3) undef
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%val1 = sub i32 %load0, %load2
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br label %endif
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endif:
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%result = phi i32 [ %val0, %if ], [ %val1, %else ]
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store i32 %result, ptr addrspace(1) %out
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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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attributes #0 = { nounwind }
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attributes #1 = { nounwind readnone }
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!llvm.module.flags = !{!0}
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!0 = !{i32 1, !"amdhsa_code_object_version", i32 400}
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