llvm-project/llvm/test/CodeGen/AMDGPU/promote-alloca-padding-size-estimate.ll

; RUN: llc -mtriple=amdgcn-amd-amdhsa < %s | FileCheck -check-prefix=GCN %s

; This shows that the amount of LDS estimate is sensitive to the order
; of the LDS globals.

; Both of these functions use the same amount of LDS, but the total
; changes depending on the visit order of first use.

; The one with the suboptimal order resulting in extra padding exceeds
; the desired limit

; The padding estimate heuristic used by the promote alloca pass
; is mostly determined by the order of the globals,

; Raw usage = 1060 bytes
; Rounded usage:
; 292 + (4 pad) + 256 + (8 pad) + 512 = 1072
; 512 + (0 pad) + 256 + (0 pad) + 292 = 1060

; At default occupancy guess of 7, 2340 bytes available total.

; 1280 need to be left to promote alloca
; optimally packed, this requires


@lds0 = internal unnamed_addr addrspace(3) global [32 x <4 x i32>] undef, align 16
@lds2 = internal unnamed_addr addrspace(3) global [32 x i64] undef, align 8
@lds1 = internal unnamed_addr addrspace(3) global [73 x i32] undef, align 4


; GCN-LABEL: {{^}}promote_alloca_size_order_0:
; GCN: workgroup_group_segment_byte_size = 2340
define void @promote_alloca_size_order_0(i32 addrspace(1)* nocapture %out, i32 addrspace(1)* nocapture %in, i32 %idx) #0 {
entry:
  %stack = alloca [5 x i32], align 4
  %tmp0 = load i32, i32 addrspace(1)* %in, align 4
  %arrayidx1 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 %tmp0
  store i32 4, i32* %arrayidx1, align 4
  %arrayidx2 = getelementptr inbounds i32, i32 addrspace(1)* %in, i32 1
  %tmp1 = load i32, i32 addrspace(1)* %arrayidx2, align 4
  %arrayidx3 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 %tmp1
  store i32 5, i32* %arrayidx3, align 4
  %arrayidx10 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 0
  %tmp2 = load i32, i32* %arrayidx10, align 4
  store i32 %tmp2, i32 addrspace(1)* %out, align 4
  %arrayidx12 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 1
  %tmp3 = load i32, i32* %arrayidx12
  %arrayidx13 = getelementptr inbounds i32, i32 addrspace(1)* %out, i32 1
  store i32 %tmp3, i32 addrspace(1)* %arrayidx13

  %gep.lds1 = getelementptr inbounds [73 x i32], [73 x i32] addrspace(3)* @lds1, i32 0, i32 %idx
  store volatile i32 0, i32 addrspace(3)* %gep.lds1, align 4

  %gep.lds2 = getelementptr inbounds [32 x i64], [32 x i64] addrspace(3)* @lds2, i32 0, i32 %idx
  store volatile i64 0, i64 addrspace(3)* %gep.lds2, align 8

  %gep.lds0 = getelementptr inbounds [32 x <4 x i32>], [32 x <4 x i32>] addrspace(3)* @lds0, i32 0, i32 %idx
  store volatile <4 x i32> zeroinitializer, <4 x i32> addrspace(3)* %gep.lds0, align 16

  ret void
}

; GCN-LABEL: {{^}}promote_alloca_size_order_1:
; GCN: workgroup_group_segment_byte_size = 2352
define void @promote_alloca_size_order_1(i32 addrspace(1)* nocapture %out, i32 addrspace(1)* nocapture %in, i32 %idx) #0 {
entry:
  %stack = alloca [5 x i32], align 4
  %tmp0 = load i32, i32 addrspace(1)* %in, align 4
  %arrayidx1 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 %tmp0
  store i32 4, i32* %arrayidx1, align 4
  %arrayidx2 = getelementptr inbounds i32, i32 addrspace(1)* %in, i32 1
  %tmp1 = load i32, i32 addrspace(1)* %arrayidx2, align 4
  %arrayidx3 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 %tmp1
  store i32 5, i32* %arrayidx3, align 4
  %arrayidx10 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 0
  %tmp2 = load i32, i32* %arrayidx10, align 4
  store i32 %tmp2, i32 addrspace(1)* %out, align 4
  %arrayidx12 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 1
  %tmp3 = load i32, i32* %arrayidx12
  %arrayidx13 = getelementptr inbounds i32, i32 addrspace(1)* %out, i32 1
  store i32 %tmp3, i32 addrspace(1)* %arrayidx13

  %gep.lds0 = getelementptr inbounds [32 x <4 x i32>], [32 x <4 x i32>] addrspace(3)* @lds0, i32 0, i32 %idx
  store volatile <4 x i32> zeroinitializer, <4 x i32> addrspace(3)* %gep.lds0, align 16

  %gep.lds2 = getelementptr inbounds [32 x i64], [32 x i64] addrspace(3)* @lds2, i32 0, i32 %idx
  store volatile i64 0, i64 addrspace(3)* %gep.lds2, align 8

  %gep.lds1 = getelementptr inbounds [73 x i32], [73 x i32] addrspace(3)* @lds1, i32 0, i32 %idx
  store volatile i32 0, i32 addrspace(3)* %gep.lds1, align 4

  ret void
}

@lds3 = internal unnamed_addr addrspace(3) global [13 x i32] undef, align 4
@lds4 = internal unnamed_addr addrspace(3) global [63 x <4 x i32>] undef, align 16

; The guess from the alignment padding pushes this over the determined
; size limit, so it isn't promoted

; GCN-LABEL: {{^}}promote_alloca_align_pad_guess_over_limit:
; GCN: workgroup_group_segment_byte_size = 1060
define void @promote_alloca_align_pad_guess_over_limit(i32 addrspace(1)* nocapture %out, i32 addrspace(1)* nocapture %in, i32 %idx) #0 {
entry:
  %stack = alloca [5 x i32], align 4
  %tmp0 = load i32, i32 addrspace(1)* %in, align 4
  %arrayidx1 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 %tmp0
  store i32 4, i32* %arrayidx1, align 4
  %arrayidx2 = getelementptr inbounds i32, i32 addrspace(1)* %in, i32 1
  %tmp1 = load i32, i32 addrspace(1)* %arrayidx2, align 4
  %arrayidx3 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 %tmp1
  store i32 5, i32* %arrayidx3, align 4
  %arrayidx10 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 0
  %tmp2 = load i32, i32* %arrayidx10, align 4
  store i32 %tmp2, i32 addrspace(1)* %out, align 4
  %arrayidx12 = getelementptr inbounds [5 x i32], [5 x i32]* %stack, i32 0, i32 1
  %tmp3 = load i32, i32* %arrayidx12
  %arrayidx13 = getelementptr inbounds i32, i32 addrspace(1)* %out, i32 1
  store i32 %tmp3, i32 addrspace(1)* %arrayidx13

  %gep.lds3 = getelementptr inbounds [13 x i32], [13 x i32] addrspace(3)* @lds3, i32 0, i32 %idx
  store volatile i32 0, i32 addrspace(3)* %gep.lds3, align 4

  %gep.lds4 = getelementptr inbounds [63 x <4 x i32>], [63 x <4 x i32>] addrspace(3)* @lds4, i32 0, i32 %idx
  store volatile <4 x i32> zeroinitializer, <4 x i32> addrspace(3)* %gep.lds4, align 16

  ret void
}

attributes #0 = { nounwind "amdgpu-max-work-group-size"="64" }