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clang-p2996/llvm/test/CodeGen/AMDGPU/resource-optimization-remarks.ll
Lucas Ramirez 6206f5444f [AMDGPU] Occupancy w.r.t. workgroup size range is also a range (#123748) 
Occupancy (i.e., the number of waves per EU) depends, in addition to
register usage, on per-workgroup LDS usage as well as on the range of
possible workgroup sizes. Mirroring the latter, occupancy should
therefore be expressed as a range since different group sizes generally
yield different achievable occupancies.

`getOccupancyWithLocalMemSize` currently returns a scalar occupancy
based on the maximum workgroup size and LDS usage. With respect to the
workgroup size range, this scalar can be the minimum, the maximum, or
neither of the two of the range of achievable occupancies. This commit
fixes the function by making it compute and return the range of
achievable occupancies w.r.t. workgroup size and LDS usage; it also
renames it to `getOccupancyWithWorkGroupSizes` since it is the range of
workgroup sizes that produces the range of achievable occupancies.

Computing the achievable occupancy range is surprisingly involved.
Minimum/maximum workgroup sizes do not necessarily yield maximum/minimum
occupancies i.e., sometimes workgroup sizes inside the range yield the
occupancy bounds. The implementation finds these sizes in constant time;
heavy documentation explains the rationale behind the sometimes
relatively obscure calculations.

As a justifying example, consider a target with 10 waves / EU, 4 EUs/CU,
64-wide waves. Also consider a function with no LDS usage and a flat
workgroup size range of [513,1024].

- A group of 513 items requires 9 waves per group. Only 4 groups made up
of 9 waves each can fit fully on a CU at any given time, for a total of
36 waves on the CU, or 9 per EU. However, filling as much as possible
the remaining 40-36=4 wave slots without decreasing the number of groups
reveals that a larger group of 640 items yields 40 waves on the CU, or
10 per EU.
- Similarly, a group of 1024 items requires 16 waves per group. Only 2
groups made up of 16 waves each can fit fully on a CU ay any given time,
for a total of 32 waves on the CU, or 8 per EU. However, removing as
many waves as possible from the groups without being able to fit another
equal-sized group on the CU reveals that a smaller group of 896 items
yields 28 waves on the CU, or 7 per EU.

Therefore the achievable occupancy range for this function is not [8,9]
as the group size bounds directly yield, but [7,10].

Naturally this change causes a lot of test churn as instruction
scheduling is driven by achievable occupancy estimates. In most unit
tests the flat workgroup size range is the default [1,1024] which,
ignoring potential LDS limitations, would previously produce a scalar
occupancy of 8 (derived from 1024) on a lot of targets, whereas we now
consider the maximum occupancy to be 10 in such cases. Most tests are
updated automatically and checked manually for sanity. I also manually
changed some non-automatically generated assertions when necessary.

Fixes #118220.
2025-01-23 16:07:57 +01:00

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; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 -pass-remarks-output=%t -pass-remarks-analysis=kernel-resource-usage -filetype=null %s 2>&1 | FileCheck -check-prefix=STDERR %s
; RUN: FileCheck -check-prefix=REMARK %s < %t
; STDERR: remark: foo.cl:27:0: Function Name: test_kernel
; STDERR-NEXT: remark: foo.cl:27:0: TotalSGPRs: 28
; STDERR-NEXT: remark: foo.cl:27:0: VGPRs: 9
; STDERR-NEXT: remark: foo.cl:27:0: AGPRs: 43
; STDERR-NEXT: remark: foo.cl:27:0: ScratchSize [bytes/lane]: 0
; STDERR-NEXT: remark: foo.cl:27:0: Dynamic Stack: False
; STDERR-NEXT: remark: foo.cl:27:0: Occupancy [waves/SIMD]: 5
; STDERR-NEXT: remark: foo.cl:27:0: SGPRs Spill: 0
; STDERR-NEXT: remark: foo.cl:27:0: VGPRs Spill: 0
; STDERR-NEXT: remark: foo.cl:27:0: LDS Size [bytes/block]: 512
; REMARK-LABEL: --- !Analysis
; REMARK: Pass: kernel-resource-usage
; REMARK-NEXT: Name: FunctionName
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: 'Function Name: '
; REMARK-NEXT: - FunctionName: test_kernel
; REMARK-NEXT: ...
; REMARK-NEXT: --- !Analysis
; REMARK-NEXT: Pass: kernel-resource-usage
; REMARK-NEXT: Name: NumSGPR
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: ' TotalSGPRs: '
; REMARK-NEXT: - NumSGPR: '28'
; REMARK-NEXT: ...
; REMARK-NEXT: --- !Analysis
; REMARK-NEXT: Pass: kernel-resource-usage
; REMARK-NEXT: Name: NumVGPR
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: ' VGPRs: '
; REMARK-NEXT: - NumVGPR: '9'
; REMARK-NEXT: ...
; REMARK-NEXT: --- !Analysis
; REMARK-NEXT: Pass: kernel-resource-usage
; REMARK-NEXT: Name: NumAGPR
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: ' AGPRs: '
; REMARK-NEXT: - NumAGPR: '43'
; REMARK-NEXT: ...
; REMARK-NEXT: --- !Analysis
; REMARK-NEXT: Pass: kernel-resource-usage
; REMARK-NEXT: Name: ScratchSize
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: ' ScratchSize [bytes/lane]: '
; REMARK-NEXT: - ScratchSize: '0'
; REMARK-NEXT: ..
; REMARK-NEXT: --- !Analysis
; REMARK-NEXT: Pass: kernel-resource-usage
; REMARK-NEXT: Name: DynamicStack
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: ' Dynamic Stack:
; REMARK-NEXT: - DynamicStack: 'False'
; REMARK-NEXT: ..
; REMARK-NEXT: --- !Analysis
; REMARK-NEXT: Pass: kernel-resource-usage
; REMARK-NEXT: Name: Occupancy
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: ' Occupancy [waves/SIMD]: '
; REMARK-NEXT: - Occupancy: '5'
; REMARK-NEXT: ...
; REMARK-NEXT: --- !Analysis
; REMARK-NEXT: Pass: kernel-resource-usage
; REMARK-NEXT: Name: SGPRSpill
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: ' SGPRs Spill: '
; REMARK-NEXT: - SGPRSpill: '0'
; REMARK-NEXT: ...
; REMARK-NEXT: --- !Analysis
; REMARK-NEXT: Pass: kernel-resource-usage
; REMARK-NEXT: Name: VGPRSpill
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: ' VGPRs Spill: '
; REMARK-NEXT: - VGPRSpill: '0'
; REMARK-NEXT: ...
; REMARK-NEXT: --- !Analysis
; REMARK-NEXT: Pass: kernel-resource-usage
; REMARK-NEXT: Name: BytesLDS
; REMARK-NEXT: DebugLoc: { File: foo.cl, Line: 27, Column: 0 }
; REMARK-NEXT: Function: test_kernel
; REMARK-NEXT: Args:
; REMARK-NEXT: - String: ' LDS Size [bytes/block]: '
; REMARK-NEXT: - BytesLDS: '512'
; REMARK-NEXT: ...
@lds = internal unnamed_addr addrspace(3) global [128 x i32] undef, align 4
define amdgpu_kernel void @test_kernel() !dbg !3 {
call void asm sideeffect "; clobber v8", "~{v8}"()
call void asm sideeffect "; clobber s23", "~{s23}"()
call void asm sideeffect "; clobber a42", "~{a42}"()
call void asm sideeffect "; use $0", "v"(ptr addrspace(3) @lds)
ret void
}
; STDERR-NOT: test_func
define void @test_func() !dbg !6 {
call void asm sideeffect "; clobber v17", "~{v17}"()
call void asm sideeffect "; clobber s11", "~{s11}"()
call void asm sideeffect "; clobber a9", "~{a9}"()
ret void
}
; STDERR: remark: foo.cl:8:0: Function Name: empty_kernel
; STDERR-NEXT: remark: foo.cl:8:0: TotalSGPRs: 4
; STDERR-NEXT: remark: foo.cl:8:0: VGPRs: 0
; STDERR-NEXT: remark: foo.cl:8:0: AGPRs: 0
; STDERR-NEXT: remark: foo.cl:8:0: ScratchSize [bytes/lane]: 0
; STDERR-NEXT: remark: foo.cl:8:0: Dynamic Stack: False
; STDERR-NEXT: remark: foo.cl:8:0: Occupancy [waves/SIMD]: 10
; STDERR-NEXT: remark: foo.cl:8:0: SGPRs Spill: 0
; STDERR-NEXT: remark: foo.cl:8:0: VGPRs Spill: 0
; STDERR-NEXT: remark: foo.cl:8:0: LDS Size [bytes/block]: 0
define amdgpu_kernel void @empty_kernel() !dbg !7 {
ret void
}
; STDERR-NOT: empty_func
define void @empty_func() !dbg !8 {
ret void
}
; STDERR: remark: foo.cl:64:0: Function Name: test_indirect_call
; STDERR-NEXT: remark: foo.cl:64:0: TotalSGPRs: test_indirect_call.numbered_sgpr+6
; STDERR-NEXT: remark: foo.cl:64:0: VGPRs: test_indirect_call.num_vgpr
; STDERR-NEXT: remark: foo.cl:64:0: AGPRs: test_indirect_call.num_agpr
; STDERR-NEXT: remark: foo.cl:64:0: ScratchSize [bytes/lane]: 0
; STDERR-NEXT: remark: foo.cl:64:0: Dynamic Stack: True
; STDERR-NEXT: remark: foo.cl:64:0: Occupancy [waves/SIMD]: occupancy(10, 4, 256, 8, 10, max(test_indirect_call.numbered_sgpr+(extrasgprs(test_indirect_call.uses_vcc, test_indirect_call.uses_flat_scratch, 1)), 1, 0), max(totalnumvgprs(test_indirect_call.num_agpr, test_indirect_call.num_vgpr), 1, 0))
; STDERR-NEXT: remark: foo.cl:64:0: SGPRs Spill: 0
; STDERR-NEXT: remark: foo.cl:64:0: VGPRs Spill: 0
; STDERR-NEXT: remark: foo.cl:64:0: LDS Size [bytes/block]: 0
@gv.fptr0 = external hidden unnamed_addr addrspace(4) constant ptr, align 4
define amdgpu_kernel void @test_indirect_call() !dbg !9 {
%fptr = load ptr, ptr addrspace(4) @gv.fptr0
call void %fptr()
ret void
}
; STDERR: remark: foo.cl:74:0: Function Name: test_indirect_w_static_stack
; STDERR-NEXT: remark: foo.cl:74:0: TotalSGPRs: test_indirect_w_static_stack.numbered_sgpr+6
; STDERR-NEXT: remark: foo.cl:74:0: VGPRs: test_indirect_w_static_stack.num_vgpr
; STDERR-NEXT: remark: foo.cl:74:0: AGPRs: test_indirect_w_static_stack.num_agpr
; STDERR-NEXT: remark: foo.cl:74:0: ScratchSize [bytes/lane]: 144
; STDERR-NEXT: remark: foo.cl:74:0: Dynamic Stack: True
; STDERR-NEXT: remark: foo.cl:74:0: Occupancy [waves/SIMD]: occupancy(10, 4, 256, 8, 10, max(test_indirect_w_static_stack.numbered_sgpr+(extrasgprs(test_indirect_w_static_stack.uses_vcc, test_indirect_w_static_stack.uses_flat_scratch, 1)), 1, 0), max(totalnumvgprs(test_indirect_w_static_stack.num_agpr, test_indirect_w_static_stack.num_vgpr), 1, 0))
; STDERR-NEXT: remark: foo.cl:74:0: SGPRs Spill: 0
; STDERR-NEXT: remark: foo.cl:74:0: VGPRs Spill: 0
; STDERR-NEXT: remark: foo.cl:74:0: LDS Size [bytes/block]: 0
declare void @llvm.memset.p5.i64(ptr addrspace(5) nocapture readonly, i8, i64, i1 immarg)
define amdgpu_kernel void @test_indirect_w_static_stack() !dbg !10 {
%alloca = alloca <10 x i64>, align 16, addrspace(5)
call void @llvm.memset.p5.i64(ptr addrspace(5) %alloca, i8 0, i64 40, i1 false)
%fptr = load ptr, ptr addrspace(4) @gv.fptr0
call void %fptr()
ret void
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2}
!llvm.module.flags = !{!11}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
!1 = !DIFile(filename: "foo.cl", directory: "/tmp")
!2 = !{i32 2, !"Debug Info Version", i32 3}
!3 = distinct !DISubprogram(name: "test_kernel", scope: !1, file: !1, type: !4, scopeLine: 27, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
!4 = !DISubroutineType(types: !5)
!5 = !{null}
!6 = distinct !DISubprogram(name: "test_func", scope: !1, file: !1, type: !4, scopeLine: 42, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
!7 = distinct !DISubprogram(name: "empty_kernel", scope: !1, file: !1, type: !4, scopeLine: 8, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
!8 = distinct !DISubprogram(name: "empty_func", scope: !1, file: !1, type: !4, scopeLine: 52, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
!9 = distinct !DISubprogram(name: "test_indirect_call", scope: !1, file: !1, type: !4, scopeLine: 64, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
!10 = distinct !DISubprogram(name: "test_indirect_w_static_stack", scope: !1, file: !1, type: !4, scopeLine: 74, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
!11 = !{i32 1, !"amdhsa_code_object_version", i32 500}
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