RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-11-22 18:54:02 +01:00
Code Issues Projects Releases Wiki Activity
5cf4e36ce1
llvm-mirror/test/CodeGen/AMDGPU/spill-m0.ll
Sebastian Neubauer f4093e4216 [AMDGPU] Save VGPR of whole wave when spilling 
Spilling SGPRs to scratch uses a temporary VGPR. LLVM currently cannot
determine if a VGPR is used in other lanes or not, so we need to save
all lanes of the VGPR. We even need to save the VGPR if it is marked as
dead.

The generated code depends on two things:
- Can we scavenge an SGPR to save EXEC?
- And can we scavenge a VGPR?

If we can scavenge an SGPR, we
- save EXEC into the SGPR
- set the needed lane mask
- save the temporary VGPR
- write the spilled SGPR into VGPR lanes
- save the VGPR again to the target stack slot
- restore the VGPR
- restore EXEC

If we were not able to scavenge an SGPR, we do the same operations, but
everytime the temporary VGPR is written to memory, we
- write VGPR to memory
- flip exec (s_not exec, exec)
- write VGPR again (previously inactive lanes)

Surprisingly often, we are able to scavenge an SGPR, even though we are
at the brink of running out of SGPRs.
Scavenging a VGPR does not have a great effect (saves three instructions
if no SGPR was scavenged), but we need to know if the VGPR we use is
live before or not, otherwise the machine verifier complains.

Differential Revision: https://reviews.llvm.org/D96336
2021-04-12 11:01:38 +02:00

194 lines
7.0 KiB
LLVM
Raw Blame History

; RUN: llc -O0 -amdgpu-spill-sgpr-to-vgpr=1 -march=amdgcn -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefix=TOVGPR -check-prefix=GCN %s
; RUN: llc -O0 -amdgpu-spill-sgpr-to-vgpr=1 -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefix=TOVGPR -check-prefix=GCN %s
; RUN: llc -O0 -amdgpu-spill-sgpr-to-vgpr=0 -march=amdgcn -mcpu=tahiti -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefix=TOVMEM -check-prefix=GCN %s
; RUN: llc -O0 -amdgpu-spill-sgpr-to-vgpr=0 -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefix=TOVMEM -check-prefix=GCN %s
; XXX - Why does it like to use vcc?
; GCN-LABEL: {{^}}spill_m0:
; GCN: #ASMSTART
; GCN-NEXT: s_mov_b32 m0, 0
; GCN-NEXT: #ASMEND
; GCN-DAG: s_mov_b32 [[M0_COPY:s[0-9]+]], m0
; TOVGPR: v_writelane_b32 [[SPILL_VREG:v[0-9]+]], [[M0_COPY]], [[M0_LANE:[0-9]+]]
; TOVMEM: s_mov_b64 [[COPY_EXEC:s\[[0-9]+:[0-9]+\]]], exec
; TOVMEM: s_mov_b64 exec, 1
; TOVMEM: v_writelane_b32 [[SPILL_VREG:v[0-9]+]], [[M0_COPY]], 0
; TOVMEM: buffer_store_dword [[SPILL_VREG]], off, s{{\[[0-9]+:[0-9]+\]}}, 0 offset:4 ; 4-byte Folded Spill
; TOVMEM: s_mov_b64 exec, [[COPY_EXEC]]
; GCN: s_cbranch_scc1 [[ENDIF:BB[0-9]+_[0-9]+]]
; GCN: [[ENDIF]]:
; TOVGPR: v_readlane_b32 [[M0_RESTORE:s[0-9]+]], [[SPILL_VREG]], [[M0_LANE]]
; TOVGPR: s_mov_b32 m0, [[M0_RESTORE]]
; TOVMEM: buffer_load_dword [[RELOAD_VREG:v[0-9]+]], off, s{{\[[0-9]+:[0-9]+\]}}, 0 offset:4 ; 4-byte Folded Reload
; TOVMEM: s_waitcnt vmcnt(0)
; TOVMEM: v_readlane_b32 [[M0_RESTORE:s[0-9]+]], [[RELOAD_VREG]], 0
; TOVMEM: s_mov_b32 m0, [[M0_RESTORE]]
; GCN: s_add_i32 s{{[0-9]+}}, m0, 1
define amdgpu_kernel void @spill_m0(i32 %cond, i32 addrspace(1)* %out) #0 {
entry:
%m0 = call i32 asm sideeffect "s_mov_b32 m0, 0", "={m0}"() #0
%cmp0 = icmp eq i32 %cond, 0
br i1 %cmp0, label %if, label %endif
if:
call void asm sideeffect "v_nop", ""() #0
br label %endif
endif:
%foo = call i32 asm sideeffect "s_add_i32 $0, $1, 1", "=s,{m0}"(i32 %m0) #0
store i32 %foo, i32 addrspace(1)* %out
ret void
}
@lds = internal addrspace(3) global [64 x float] undef
; m0 is killed, so it isn't necessary during the entry block spill to preserve it
; GCN-LABEL: {{^}}spill_kill_m0_lds:
; GCN-NOT: v_readlane_b32 m0
; GCN-NOT: s_buffer_store_dword m0
; GCN-NOT: s_buffer_load_dword m0
define amdgpu_ps void @spill_kill_m0_lds(<16 x i8> addrspace(4)* inreg %arg, <16 x i8> addrspace(4)* inreg %arg1, <32 x i8> addrspace(4)* inreg %arg2, i32 inreg %m0) #0 {
main_body:
%tmp = call float @llvm.amdgcn.interp.mov(i32 2, i32 0, i32 0, i32 %m0)
%cmp = fcmp ueq float 0.000000e+00, %tmp
br i1 %cmp, label %if, label %else
if: ; preds = %main_body
%lds_ptr = getelementptr [64 x float], [64 x float] addrspace(3)* @lds, i32 0, i32 0
%lds_data_ = load float, float addrspace(3)* %lds_ptr
%lds_data = call float @llvm.amdgcn.wqm.f32(float %lds_data_)
br label %endif
else: ; preds = %main_body
%interp = call float @llvm.amdgcn.interp.mov(i32 2, i32 0, i32 0, i32 %m0)
br label %endif
endif: ; preds = %else, %if
%export = phi float [ %lds_data, %if ], [ %interp, %else ]
%tmp4 = call <2 x half> @llvm.amdgcn.cvt.pkrtz(float %export, float %export)
call void @llvm.amdgcn.exp.compr.v2f16(i32 0, i32 15, <2 x half> %tmp4, <2 x half> %tmp4, i1 true, i1 true) #0
ret void
}
; Force save and restore of m0 during SMEM spill
; GCN-LABEL: {{^}}m0_unavailable_spill:
; GCN: s_load_dword [[REG0:s[0-9]+]], s[0:1], {{0x[0-9]+}}
; GCN: ; def m0, 1
; GCN: s_mov_b32 m0, [[REG0]]
; GCN: v_interp_mov_f32
; GCN: ; clobber m0
; TOSMEM: s_mov_b32 s2, m0
; TOSMEM: s_add_u32 m0, s3, 0x100
; TOSMEM-NEXT: s_buffer_store_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s{{\[[0-9]+:[0-9]+\]}}, m0 ; 8-byte Folded Spill
; TOSMEM: s_mov_b32 m0, s2
; TOSMEM: s_mov_b64 exec,
; TOSMEM: s_cbranch_execz
; TOSMEM: s_branch
; TOSMEM: BB{{[0-9]+_[0-9]+}}:
; TOSMEM: s_add_u32 m0, s3, 0x100
; TOSMEM-NEXT: s_buffer_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s{{\[[0-9]+:[0-9]+\]}}, m0 ; 8-byte Folded Reload
; GCN-NOT: v_readlane_b32 m0
; GCN-NOT: s_buffer_store_dword m0
; GCN-NOT: s_buffer_load_dword m0
define amdgpu_kernel void @m0_unavailable_spill(i32 %m0.arg) #0 {
main_body:
%m0 = call i32 asm sideeffect "; def $0, 1", "={m0}"() #0
%tmp = call float @llvm.amdgcn.interp.mov(i32 2, i32 0, i32 0, i32 %m0.arg)
call void asm sideeffect "; clobber $0", "~{m0}"() #0
%cmp = fcmp ueq float 0.000000e+00, %tmp
br i1 %cmp, label %if, label %else
if: ; preds = %main_body
store volatile i32 8, i32 addrspace(1)* undef
br label %endif
else: ; preds = %main_body
store volatile i32 11, i32 addrspace(1)* undef
br label %endif
endif:
ret void
}
; GCN-LABEL: {{^}}restore_m0_lds:
; FIXME: RegScavenger::isRegUsed() always returns true if m0 is reserved, so we have to save and restore it
; FIXME-TOSMEM-NOT: m0
; TOSMEM: s_add_u32 m0, s3, {{0x[0-9]+}}
; TOSMEM: s_buffer_store_dword s1, s[88:91], m0 ; 4-byte Folded Spill
; FIXME-TOSMEM-NOT: m0
; TOSMEM: s_load_dwordx2 [[REG:s\[[0-9]+:[0-9]+\]]]
; TOSMEM: s_add_u32 m0, s3, {{0x[0-9]+}}
; TOSMEM: s_waitcnt lgkmcnt(0)
; TOSMEM: s_buffer_store_dwordx2 [[REG]], s[88:91], m0 ; 8-byte Folded Spill
; FIXME-TOSMEM-NOT: m0
; TOSMEM: s_cmp_eq_u32
; TOSMEM: s_cbranch_scc1
; TOSMEM: s_mov_b32 m0, -1
; TOSMEM: s_mov_b32 s2, m0
; TOSMEM: s_add_u32 m0, s3, 0x200
; TOSMEM: s_buffer_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s[88:91], m0 ; 8-byte Folded Reload
; TOSMEM: s_mov_b32 m0, s2
; TOSMEM: s_waitcnt lgkmcnt(0)
; TOSMEM: ds_write_b64
; FIXME-TOSMEM-NOT: m0
; TOSMEM: s_add_u32 m0, s3, 0x100
; TOSMEM: s_buffer_load_dword s2, s[88:91], m0 ; 4-byte Folded Reload
; FIXME-TOSMEM-NOT: m0
; TOSMEM: s_mov_b32 [[REG1:s[0-9]+]], m0
; TOSMEM: s_add_u32 m0, s3, 0x100
; TOSMEM: s_buffer_load_dwordx2 s{{\[[0-9]+:[0-9]+\]}}, s[88:91], m0 ; 8-byte Folded Reload
; TOSMEM: s_mov_b32 m0, [[REG1]]
; TOSMEM: s_mov_b32 m0, -1
; TOSMEM: s_waitcnt lgkmcnt(0)
; TOSMEM-NOT: m0
; TOSMEM: s_mov_b32 m0, s2
; TOSMEM: ; use m0
; TOSMEM: s_dcache_wb
; TOSMEM: s_endpgm
define amdgpu_kernel void @restore_m0_lds(i32 %arg) {
%m0 = call i32 asm sideeffect "s_mov_b32 m0, 0", "={m0}"() #0
%sval = load volatile i64, i64 addrspace(4)* undef
%cmp = icmp eq i32 %arg, 0
br i1 %cmp, label %ret, label %bb
bb:
store volatile i64 %sval, i64 addrspace(3)* undef
call void asm sideeffect "; use $0", "{m0}"(i32 %m0) #0
br label %ret
ret:
ret void
}
declare float @llvm.amdgcn.interp.mov(i32, i32, i32, i32) #1
declare void @llvm.amdgcn.exp.f32(i32, i32, float, float, float, float, i1, i1) #0
declare void @llvm.amdgcn.exp.compr.v2f16(i32, i32, <2 x half>, <2 x half>, i1, i1) #0
declare <2 x half> @llvm.amdgcn.cvt.pkrtz(float, float) #1
declare float @llvm.amdgcn.wqm.f32(float) #1
attributes #0 = { nounwind }
attributes #1 = { nounwind readnone }
Reference in New Issue View Git Blame Copy Permalink