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clang-p2996/llvm/test/CodeGen/AMDGPU/stack-realign.ll
Venkata Ramanaiah Nalamothu 04fff547e2 [AMDGPU] Move call clobbered return address registers s[30:31] to callee saved range 
Currently the return address ABI registers s[30:31], which fall in the call
clobbered register range, are added as a live-in on the function entry to
preserve its value when we have calls so that it gets saved and restored
around the calls.

But the DWARF unwind information (CFI) needs to track where the return address
resides in a frame and the above approach makes it difficult to track the
return address when the CFI information is emitted during the frame lowering,
due to the involvment of understanding the control flow.

This patch moves the return address ABI registers s[30:31] into callee saved
registers range and stops adding live-in for return address registers, so that
the CFI machinery will know where the return address resides when CSR
save/restore happen during the frame lowering.

And doing the above poses an issue that now the return instruction uses undefined
register `sgpr30_sgpr31`. This is resolved by hiding the return address register
use by the return instruction through the `SI_RETURN` pseudo instruction, which
doesn't take any input operands, until the `SI_RETURN` pseudo gets lowered to the
`S_SETPC_B64_return` during the `expandPostRAPseudo()`.

As an added benefit, this patch simplifies overall return instruction handling.

Note: The AMDGPU CFI changes are there only in the downstream code and another
version of this patch will be posted for review for the downstream code.

Reviewed By: arsenm, ronlieb

Differential Revision: https://reviews.llvm.org/D114652
2022-03-09 12:18:02 +05:30

337 lines
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; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=fiji -verify-machineinstrs < %s | FileCheck -check-prefix=GCN %s
; Check that we properly realign the stack. While 4-byte access is all
; that is ever needed, some transformations rely on the known bits from the alignment of the pointer (e.g.
; 128 byte object
; 4 byte emergency stack slot
; = 144 bytes with padding between them
; GCN-LABEL: {{^}}needs_align16_default_stack_align:
; GCN-DAG: v_lshlrev_b32_e32 [[SCALED_IDX:v[0-9]+]], 4, v0
; GCN-DAG: v_lshrrev_b32_e64 [[FRAMEDIFF:v[0-9]+]], 6, s32
; GCN: v_add_u32_e32 [[FI:v[0-9]+]], vcc, [[FRAMEDIFF]], [[SCALED_IDX]]
; GCN-NOT: s32
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: v_or_b32_e32 v{{[0-9]+}}, 12
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN-NOT: s32
; GCN: ; ScratchSize: 144
define void @needs_align16_default_stack_align(i32 %idx) #0 {
%alloca.align16 = alloca [8 x <4 x i32>], align 16, addrspace(5)
%gep0 = getelementptr inbounds [8 x <4 x i32>], [8 x <4 x i32>] addrspace(5)* %alloca.align16, i32 0, i32 %idx
store volatile <4 x i32> <i32 1, i32 2, i32 3, i32 4>, <4 x i32> addrspace(5)* %gep0, align 16
ret void
}
; GCN-LABEL: {{^}}needs_align16_stack_align4:
; GCN: s_add_i32 [[SCRATCH_REG:s[0-9]+]], s32, 0x3c0{{$}}
; GCN: s_and_b32 s33, [[SCRATCH_REG]], 0xfffffc00
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: v_or_b32_e32 v{{[0-9]+}}, 12
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: s_addk_i32 s32, 0x2800{{$}}
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: s_addk_i32 s32, 0xd800
; GCN: ; ScratchSize: 160
define void @needs_align16_stack_align4(i32 %idx) #2 {
%alloca.align16 = alloca [8 x <4 x i32>], align 16, addrspace(5)
%gep0 = getelementptr inbounds [8 x <4 x i32>], [8 x <4 x i32>] addrspace(5)* %alloca.align16, i32 0, i32 %idx
store volatile <4 x i32> <i32 1, i32 2, i32 3, i32 4>, <4 x i32> addrspace(5)* %gep0, align 16
ret void
}
; GCN-LABEL: {{^}}needs_align32:
; GCN: s_add_i32 [[SCRATCH_REG:s[0-9]+]], s32, 0x7c0{{$}}
; GCN: s_and_b32 s33, [[SCRATCH_REG]], 0xfffff800
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: v_or_b32_e32 v{{[0-9]+}}, 12
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: s_addk_i32 s32, 0x3000{{$}}
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: s_addk_i32 s32, 0xd000
; GCN: ; ScratchSize: 192
define void @needs_align32(i32 %idx) #0 {
%alloca.align16 = alloca [8 x <4 x i32>], align 32, addrspace(5)
%gep0 = getelementptr inbounds [8 x <4 x i32>], [8 x <4 x i32>] addrspace(5)* %alloca.align16, i32 0, i32 %idx
store volatile <4 x i32> <i32 1, i32 2, i32 3, i32 4>, <4 x i32> addrspace(5)* %gep0, align 32
ret void
}
; GCN-LABEL: {{^}}force_realign4:
; GCN: s_add_i32 [[SCRATCH_REG:s[0-9]+]], s32, 0xc0{{$}}
; GCN: s_and_b32 s33, [[SCRATCH_REG]], 0xffffff00
; GCN: s_addk_i32 s32, 0xd00{{$}}
; GCN: buffer_store_dword v{{[0-9]+}}, v{{[0-9]+}}, s[0:3], 0 offen
; GCN: s_addk_i32 s32, 0xf300
; GCN: ; ScratchSize: 52
define void @force_realign4(i32 %idx) #1 {
%alloca.align16 = alloca [8 x i32], align 4, addrspace(5)
%gep0 = getelementptr inbounds [8 x i32], [8 x i32] addrspace(5)* %alloca.align16, i32 0, i32 %idx
store volatile i32 3, i32 addrspace(5)* %gep0, align 4
ret void
}
; GCN-LABEL: {{^}}kernel_call_align16_from_8:
; GCN: s_movk_i32 s32, 0x400{{$}}
; GCN-NOT: s32
; GCN: s_swappc_b64
define amdgpu_kernel void @kernel_call_align16_from_8() #0 {
%alloca = alloca i32, align 4, addrspace(5)
store volatile i32 2, i32 addrspace(5)* %alloca
call void @needs_align16_default_stack_align(i32 1)
ret void
}
; The call sequence should keep the stack on call aligned to 4
; GCN-LABEL: {{^}}kernel_call_align16_from_5:
; GCN: s_movk_i32 s32, 0x400
; GCN: s_swappc_b64
define amdgpu_kernel void @kernel_call_align16_from_5() {
%alloca0 = alloca i8, align 1, addrspace(5)
store volatile i8 2, i8 addrspace(5)* %alloca0
call void @needs_align16_default_stack_align(i32 1)
ret void
}
; GCN-LABEL: {{^}}kernel_call_align4_from_5:
; GCN: s_movk_i32 s32, 0x400
; GCN: s_swappc_b64
define amdgpu_kernel void @kernel_call_align4_from_5() {
%alloca0 = alloca i8, align 1, addrspace(5)
store volatile i8 2, i8 addrspace(5)* %alloca0
call void @needs_align16_stack_align4(i32 1)
ret void
}
; GCN-LABEL: {{^}}default_realign_align128:
; GCN: s_mov_b32 [[FP_COPY:s[0-9]+]], s33
; GCN-NEXT: s_add_i32 s33, s32, 0x1fc0
; GCN-NEXT: s_and_b32 s33, s33, 0xffffe000
; GCN-NEXT: s_addk_i32 s32, 0x4000
; GCN-NOT: s33
; GCN: buffer_store_dword v0, off, s[0:3], s33{{$}}
; GCN: s_addk_i32 s32, 0xc000
; GCN: s_mov_b32 s33, [[FP_COPY]]
define void @default_realign_align128(i32 %idx) #0 {
%alloca.align = alloca i32, align 128, addrspace(5)
store volatile i32 9, i32 addrspace(5)* %alloca.align, align 128
ret void
}
; GCN-LABEL: {{^}}disable_realign_align128:
; GCN-NOT: s32
; GCN: buffer_store_dword v0, off, s[0:3], s32{{$}}
; GCN-NOT: s32
define void @disable_realign_align128(i32 %idx) #3 {
%alloca.align = alloca i32, align 128, addrspace(5)
store volatile i32 9, i32 addrspace(5)* %alloca.align, align 128
ret void
}
declare void @extern_func(<32 x i32>, i32) #0
define void @func_call_align1024_bp_gets_vgpr_spill(<32 x i32> %a, i32 %b) #0 {
; The test forces the stack to be realigned to a new boundary
; since there is a local object with an alignment of 1024.
; Should use BP to access the incoming stack arguments.
; The BP value is saved/restored with a VGPR spill.
; GCN-LABEL: func_call_align1024_bp_gets_vgpr_spill:
; GCN: buffer_store_dword [[VGPR_REG:v[0-9]+]], off, s[0:3], s32 offset:1028 ; 4-byte Folded Spill
; GCN-NEXT: s_mov_b64 exec, s[16:17]
; GCN-NEXT: v_writelane_b32 [[VGPR_REG]], s33, 2
; GCN-DAG: s_add_i32 [[SCRATCH_REG:s[0-9]+]], s32, 0xffc0
; GCN: s_and_b32 s33, [[SCRATCH_REG]], 0xffff0000
; GCN: v_mov_b32_e32 v32, 0
; GCN-DAG: v_writelane_b32 [[VGPR_REG]], s34, 3
; GCN: s_mov_b32 s34, s32
; GCN: buffer_store_dword v32, off, s[0:3], s33 offset:1024
; GCN-NEXT: s_waitcnt vmcnt(0)
; GCN-NEXT: buffer_load_dword v{{[0-9]+}}, off, s[0:3], s34
; GCN-DAG: s_add_i32 s32, s32, 0x30000
; GCN: buffer_store_dword v{{[0-9]+}}, off, s[0:3], s32
; GCN: s_swappc_b64 s[30:31],
; GCN: v_readlane_b32 s31, [[VGPR_REG]], 1
; GCN: v_readlane_b32 s30, [[VGPR_REG]], 0
; GCN: s_add_i32 s32, s32, 0xfffd0000
; GCN-NEXT: v_readlane_b32 s33, [[VGPR_REG]], 2
; GCN-NEXT: v_readlane_b32 s34, [[VGPR_REG]], 3
; GCN-NEXT: s_or_saveexec_b64 s[4:5], -1
; GCN-NEXT: buffer_load_dword [[VGPR_REG]], off, s[0:3], s32 offset:1028 ; 4-byte Folded Reload
; GCN-NEXT: s_mov_b64 exec, s[4:5]
; GCN: s_setpc_b64 s[30:31]
%temp = alloca i32, align 1024, addrspace(5)
store volatile i32 0, i32 addrspace(5)* %temp, align 1024
call void @extern_func(<32 x i32> %a, i32 %b)
ret void
}
%struct.Data = type { [9 x i32] }
define i32 @needs_align1024_stack_args_used_inside_loop(%struct.Data addrspace(5)* nocapture readonly byval(%struct.Data) align 8 %arg) local_unnamed_addr #4 {
; The local object allocation needed an alignment of 1024.
; Since the function argument is accessed in a loop with an
; index variable, the base pointer first get loaded into a VGPR
; and that value should be further referenced to load the incoming values.
; The BP value will get saved/restored in an SGPR at the prolgoue/epilogue.
; GCN-LABEL: needs_align1024_stack_args_used_inside_loop:
; GCN: s_mov_b32 [[FP_COPY:s[0-9]+]], s33
; GCN-NEXT: s_mov_b32 [[BP_COPY:s[0-9]+]], s34
; GCN-NEXT: s_add_i32 s33, s32, 0xffc0
; GCN-NEXT: s_mov_b32 s34, s32
; GCN-NEXT: s_and_b32 s33, s33, 0xffff0000
; GCN-NEXT: v_lshrrev_b32_e64 [[VGPR_REG:v[0-9]+]], 6, s34
; GCN-NEXT: v_mov_b32_e32 v{{[0-9]+}}, 0
; GCN: s_add_i32 s32, s32, 0x30000
; GCN: buffer_store_dword v{{[0-9]+}}, off, s[0:3], s33 offset:1024
; GCN: buffer_load_dword v{{[0-9]+}}, [[VGPR_REG]], s[0:3], 0 offen
; GCN: v_add_u32_e32 [[VGPR_REG]], vcc, 4, [[VGPR_REG]]
; GCN: s_add_i32 s32, s32, 0xfffd0000
; GCN-NEXT: s_mov_b32 s33, [[FP_COPY]]
; GCN-NEXT: s_mov_b32 s34, [[BP_COPY]]
; GCN-NEXT: s_setpc_b64 s[30:31]
begin:
%local_var = alloca i32, align 1024, addrspace(5)
store volatile i32 0, i32 addrspace(5)* %local_var, align 1024
br label %loop_body
loop_end: ; preds = %loop_body
%idx_next = add nuw nsw i32 %lp_idx, 1
%lp_exit_cond = icmp eq i32 %idx_next, 9
br i1 %lp_exit_cond, label %exit, label %loop_body
loop_body: ; preds = %loop_end, %begin
%lp_idx = phi i32 [ 0, %begin ], [ %idx_next, %loop_end ]
%ptr = getelementptr inbounds %struct.Data, %struct.Data addrspace(5)* %arg, i32 0, i32 0, i32 %lp_idx
%val = load i32, i32 addrspace(5)* %ptr, align 8
%lp_cond = icmp eq i32 %val, %lp_idx
br i1 %lp_cond, label %loop_end, label %exit
exit: ; preds = %loop_end, %loop_body
%out = phi i32 [ 0, %loop_body ], [ 1, %loop_end ]
ret i32 %out
}
define void @no_free_scratch_sgpr_for_bp_copy(<32 x i32> %a, i32 %b) #0 {
; GCN-LABEL: no_free_scratch_sgpr_for_bp_copy:
; GCN: ; %bb.0:
; GCN: v_writelane_b32 [[VGPR_REG:v[0-9]+]], s34, 0
; GCN-NEXT: s_mov_b32 s34, s32
; GCN-NEXT: buffer_load_dword v{{[0-9]+}}, off, s[0:3], s34
; GCN: v_readlane_b32 s34, [[VGPR_REG:v[0-9]+]], 0
; GCN: buffer_store_dword v{{[0-9]+}}, off, s[0:3], s33 offset:128
; GCN-NEXT: s_waitcnt vmcnt(0)
; GCN-NEXT: ;;#ASMSTART
; GCN-NEXT: ;;#ASMEND
; GCN: s_setpc_b64 s[30:31]
%local_val = alloca i32, align 128, addrspace(5)
store volatile i32 %b, i32 addrspace(5)* %local_val, align 128
; Use all clobberable registers, so BP has to spill to a VGPR.
call void asm sideeffect "",
"~{s0},~{s1},~{s2},~{s3},~{s4},~{s5},~{s6},~{s7},~{s8},~{s9}
,~{s10},~{s11},~{s12},~{s13},~{s14},~{s15},~{s16},~{s17},~{s18},~{s19}
,~{s20},~{s21},~{s22},~{s23},~{s24},~{s25},~{s26},~{s27},~{s28},~{s29}
,~{vcc_hi}"() #0
ret void
}
define void @no_free_regs_spill_bp_to_memory(<32 x i32> %a, i32 %b) #5 {
; If there are no free SGPRs or VGPRs available we must spill the BP to memory.
; GCN-LABEL: no_free_regs_spill_bp_to_mem
; GCN: s_or_saveexec_b64 s[4:5], -1
; GCN: v_mov_b32_e32 v0, s33
; GCN: buffer_store_dword v0, off, s[0:3], s32
; GCN: v_mov_b32_e32 v0, s34
; GCN-DAG: buffer_store_dword v0, off, s[0:3], s32
%local_val = alloca i32, align 128, addrspace(5)
store volatile i32 %b, i32 addrspace(5)* %local_val, align 128
call void asm sideeffect "; clobber nonpreserved SGPRs and 64 CSRs",
"~{s4},~{s5},~{s6},~{s7},~{s8},~{s9}
,~{s10},~{s11},~{s12},~{s13},~{s14},~{s15},~{s16},~{s17},~{s18},~{s19}
,~{s20},~{s21},~{s22},~{s23},~{s24},~{s25},~{s26},~{s27},~{s28},~{s29}
,~{s40},~{s41},~{s42},~{s43},~{s44},~{s45},~{s46},~{s47},~{s48},~{s49}
,~{s50},~{s51},~{s52},~{s53},~{s54},~{s55},~{s56},~{s57},~{s58},~{s59}
,~{s60},~{s61},~{s62},~{s63},~{s64},~{s65},~{s66},~{s67},~{s68},~{s69}
,~{s70},~{s71},~{s72},~{s73},~{s74},~{s75},~{s76},~{s77},~{s78},~{s79}
,~{s80},~{s81},~{s82},~{s83},~{s84},~{s85},~{s86},~{s87},~{s88},~{s89}
,~{s90},~{s91},~{s92},~{s93},~{s94},~{s95},~{s96},~{s97},~{s98},~{s99}
,~{s100},~{s101},~{s102},~{s39},~{vcc}"() #0
call void asm sideeffect "; clobber all VGPRs",
"~{v0},~{v1},~{v2},~{v3},~{v4},~{v5},~{v6},~{v7},~{v8},~{v9}
,~{v10},~{v11},~{v12},~{v13},~{v14},~{v15},~{v16},~{v17},~{v18},~{v19}
,~{v20},~{v21},~{v22},~{v23},~{v24},~{v25},~{v26},~{v27},~{v28},~{v29}
,~{v30},~{v31},~{v32},~{v33},~{v34},~{v35},~{v36},~{v37},~{v38}" () #0
ret void
}
define void @spill_bp_to_memory_scratch_reg_needed_mubuf_offset(<32 x i32> %a, i32 %b, [4096 x i8] addrspace(5)* byval([4096 x i8]) align 4 %arg) #5 {
; If the size of the offset exceeds the MUBUF offset field we need another
; scratch VGPR to hold the offset.
; GCN-LABEL: spill_bp_to_memory_scratch_reg_needed_mubuf_offset
; GCN: s_or_saveexec_b64 s[4:5], -1
; GCN-NEXT: s_add_i32 s6, s32, 0x42100
; GCN-NEXT: buffer_store_dword v39, off, s[0:3], s6 ; 4-byte Folded Spill
; GCN-NEXT: s_mov_b64 exec, s[4:5]
; GCN-NEXT: v_mov_b32_e32 v0, s33
; GCN-NOT: v_mov_b32_e32 v0, 0x1088
; GCN-NEXT: s_add_i32 s6, s32, 0x42200
; GCN-NEXT: buffer_store_dword v0, off, s[0:3], s6 ; 4-byte Folded Spill
; GCN-NEXT: v_mov_b32_e32 v0, s34
; GCN-NOT: v_mov_b32_e32 v0, 0x108c
; GCN-NEXT: s_add_i32 s6, s32, 0x42300
; GCN-NEXT: s_mov_b32 s34, s32
; GCN-NEXT: buffer_store_dword v0, off, s[0:3], s6 ; 4-byte Folded Spill
%local_val = alloca i32, align 128, addrspace(5)
store volatile i32 %b, i32 addrspace(5)* %local_val, align 128
call void asm sideeffect "; clobber nonpreserved SGPRs and 64 CSRs",
"~{s4},~{s5},~{s6},~{s7},~{s8},~{s9}
,~{s10},~{s11},~{s12},~{s13},~{s14},~{s15},~{s16},~{s17},~{s18},~{s19}
,~{s20},~{s21},~{s22},~{s23},~{s24},~{s25},~{s26},~{s27},~{s28},~{s29}
,~{s40},~{s41},~{s42},~{s43},~{s44},~{s45},~{s46},~{s47},~{s48},~{s49}
,~{s50},~{s51},~{s52},~{s53},~{s54},~{s55},~{s56},~{s57},~{s58},~{s59}
,~{s60},~{s61},~{s62},~{s63},~{s64},~{s65},~{s66},~{s67},~{s68},~{s69}
,~{s70},~{s71},~{s72},~{s73},~{s74},~{s75},~{s76},~{s77},~{s78},~{s79}
,~{s80},~{s81},~{s82},~{s83},~{s84},~{s85},~{s86},~{s87},~{s88},~{s89}
,~{s90},~{s91},~{s92},~{s93},~{s94},~{s95},~{s96},~{s97},~{s98},~{s99}
,~{s100},~{s101},~{s102},~{s39},~{vcc}"() #0
call void asm sideeffect "; clobber all VGPRs",
"~{v0},~{v1},~{v2},~{v3},~{v4},~{v5},~{v6},~{v7},~{v8},~{v9}
,~{v10},~{v11},~{v12},~{v13},~{v14},~{v15},~{v16},~{v17},~{v18},~{v19}
,~{v20},~{v21},~{v22},~{v23},~{v24},~{v25},~{v26},~{v27},~{v28},~{v29}
,~{v30},~{v31},~{v32},~{v33},~{v34},~{v35},~{v36},~{v37},~{v38}"() #0
ret void
}
attributes #0 = { noinline nounwind }
attributes #1 = { noinline nounwind "stackrealign" }
attributes #2 = { noinline nounwind alignstack=4 }
attributes #3 = { noinline nounwind "no-realign-stack" }
attributes #4 = { noinline nounwind "frame-pointer"="all"}
attributes #5 = { noinline nounwind "amdgpu-waves-per-eu"="6,6" }
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