JIT: Support last-use copy omission for commas #87548
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Allow last-use copy omission to kick in when the argument is a comma (typically created by physical promotion). Also handle this pattern in arg evaluation: avoid creating a new local for the COMMA(..., LCL_ADDR) created for this pattern. As part of this rename the "needs temp" terminology to "needs early evaluation" since these cases do not actually need or create a temp. There were other cases already where we did not create a temp (specifically handling of GT_MKREFANY), so the terminology was already a bit misleading. Fix dotnet#87471
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch Issue DetailsAllow last-use copy omission to kick in when the argument is a comma (typically created by physical promotion). Also handle this pattern in arg evaluation: avoid creating a new local for the COMMA(..., LCL_ADDR) created for this pattern. As part of this rename the "needs temp" terminology to "needs early evaluation" since these cases do not actually need or create a temp. There were other cases already where we did not create a temp (specifically handling of GT_MKREFANY), so the terminology was already a bit misleading. Fix #87471
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Example codegen diff: G_M55686_IG10:
- mov dword ptr [rsp+94H], r12d
- vmovdqu ymm0, ymmword ptr [rsp+88H]
- vmovdqu ymmword ptr [rsp+48H], ymm0
- mov dword ptr [rsp+74H], edx
- vmovdqu ymm0, ymmword ptr [rsp+68H]
- vmovdqu ymmword ptr [rsp+28H], ymm0
+ mov dword ptr [rsp+54H], r12d
+ mov dword ptr [rsp+34H], edx
mov rcx, gword ptr [rbx+08H]
lea rdx, [rsp+48H]
lea r8, [rsp+28H]
call [rbx+18H]System.Comparison`1[System.Collections.BigStruct]:Invoke(System.Collections.BigStruct,System.Collections.BigStruct):int:this
jitdump before: fgMorphTree BB13, STMT00013 (before)
[000129] DACXG------ ▌ STORE_LCL_VAR int V06 tmp1
[000037] -ACXG------ └──▌ CALL int System.Comparison`1[System.Collections.BigStruct]:Invoke(System.Collections.BigStruct,System.Collections.BigStruct):int:this
[000006] ----------- this ├──▌ LCL_VAR ref V01 arg1 (last use)
[000207] -A--------- arg1 ├──▌ COMMA struct
[000206] UA--------- │ ├──▌ STORE_LCL_FLD int V07 tmp2 [+12]
[000205] ----------- │ │ └──▌ LCL_VAR int V17 tmp12
[000107] ----------- │ └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V07 tmp2 (last use)
[000210] -A--------- arg2 └──▌ COMMA struct
[000209] UA--------- ├──▌ STORE_LCL_FLD int V08 tmp3 [+12]
[000208] ----------- │ └──▌ LCL_VAR int V18 tmp13
[000109] ----------- └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V08 tmp3 (last use)
Initializing arg info for 37.CALL:
Args for call [000037] CALL after AddFinalArgsAndDetermineABIInfo:
CallArg[[000006].LCL_VAR ref (By value), 1 reg: rcx, byteAlignment=8, wellKnown[ThisPointer]]
CallArg[[000207].COMMA struct (By ref), 1 reg: rdx, byteAlignment=8, isStruct]
CallArg[[000210].COMMA struct (By ref), 1 reg: r8, byteAlignment=8, isStruct]
Morphing args for 37.CALL:
making an outgoing copy for struct arg
lvaGrabTemp returning 23 (V23 tmp18) called for by-value struct argument.
MorphCopyBlock:
PrepareDst for [000226] have found a local var V23.
GenTreeNode creates assertion:
[000226] DA--------- ▌ STORE_LCL_VAR struct<System.Collections.BigStruct, 32> V23 tmp18
In BB13 New Local Copy Assertion: V23 == V07, index = #01
block assignment to morph:
[000226] DA--------- ▌ STORE_LCL_VAR struct<System.Collections.BigStruct, 32> V23 tmp18
[000107] -----+----- └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V07 tmp2 (last use)
with no promoted structs this requires a CopyBlock.
MorphCopyBlock (after):
[000207] -A---+----- ▌ COMMA void
[000206] UA---+----- ├──▌ STORE_LCL_FLD int V07 tmp2 [+12]
[000205] -----+----- │ └──▌ LCL_VAR int V17 tmp12
[000226] DA---+----- └──▌ STORE_LCL_VAR struct<System.Collections.BigStruct, 32> V23 tmp18
[000107] -----+----- └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V07 tmp2 (last use)
making an outgoing copy for struct arg
lvaGrabTemp returning 24 (V24 tmp19) called for by-value struct argument.
MorphCopyBlock:
PrepareDst for [000227] have found a local var V24.
GenTreeNode creates assertion:
[000227] DA--------- ▌ STORE_LCL_VAR struct<System.Collections.BigStruct, 32> V24 tmp19
In BB13 New Local Copy Assertion: V24 == V08, index = #02
block assignment to morph:
[000227] DA--------- ▌ STORE_LCL_VAR struct<System.Collections.BigStruct, 32> V24 tmp19
[000109] -----+----- └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V08 tmp3 (last use)
with no promoted structs this requires a CopyBlock.
MorphCopyBlock (after):
[000210] -A---+----- ▌ COMMA void
[000209] UA---+----- ├──▌ STORE_LCL_FLD int V08 tmp3 [+12]
[000208] -----+----- │ └──▌ LCL_VAR int V18 tmp13
[000227] DA---+----- └──▌ STORE_LCL_VAR struct<System.Collections.BigStruct, 32> V24 tmp19
[000109] -----+----- └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V08 tmp3 (last use)
Sorting the arguments:
Argument with 'side effect'...
[000006] -----+----- ▌ LCL_VAR ref V01 arg1 (last use)
lvaGrabTemp returning 25 (V25 tmp20) called for argument with side effect.
Evaluate to a temp:
[000228] DA--------- ▌ STORE_LCL_VAR ref V25 tmp20
[000006] -----+----- └──▌ LCL_VAR ref V01 arg1 (last use)
Local V23 should not be enregistered because: it is address exposed
Local V24 should not be enregistered because: it is address exposed
Register placement order: rcx rdx r8
Args for [000037].CALL after fgMorphArgs:
CallArg[[000229].LCL_VAR ref (By value), 1 reg: rcx, byteAlignment=8, isLate, tmpNum=V25, isTmp, processed, wellKnown[ThisPointer]]
CallArg[[000230].LCL_ADDR struct (By ref), 1 reg: rdx, byteAlignment=8, isLate, tmpNum=V23, isTmp, processed, isStruct]
CallArg[[000231].LCL_ADDR struct (By ref), 1 reg: r8, byteAlignment=8, isLate, tmpNum=V24, isTmp, processed, isStruct]
OutgoingArgsStackSize is 32
fgMorphTree BB13, STMT00013 (after)
[000129] DACXG+----- ▌ STORE_LCL_VAR int V06 tmp1
[000037] -ACXG+----- └──▌ CALL int System.Comparison`1[System.Collections.BigStruct]:Invoke(System.Collections.BigStruct,System.Collections.BigStruct):int:this
[000228] DA--------- this setup ├──▌ STORE_LCL_VAR ref V25 tmp20
[000006] -----+----- │ └──▌ LCL_VAR ref V01 arg1 (last use)
[000207] -A---+----- arg1 setup ├──▌ COMMA void
[000206] UA---+----- │ ├──▌ STORE_LCL_FLD int V07 tmp2 [+12]
[000205] -----+----- │ │ └──▌ LCL_VAR int V17 tmp12
[000226] DA---+----- │ └──▌ STORE_LCL_VAR struct<System.Collections.BigStruct, 32>(AX) V23 tmp18
[000107] -----+----- │ └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V07 tmp2 (last use)
[000210] -A---+----- arg2 setup ├──▌ COMMA void
[000209] UA---+----- │ ├──▌ STORE_LCL_FLD int V08 tmp3 [+12]
[000208] -----+----- │ │ └──▌ LCL_VAR int V18 tmp13
[000227] DA---+----- │ └──▌ STORE_LCL_VAR struct<System.Collections.BigStruct, 32>(AX) V24 tmp19
[000109] -----+----- │ └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V08 tmp3 (last use)
[000229] ----------- this in rcx ├──▌ LCL_VAR ref V25 tmp20
[000230] ----------- arg1 in rdx ├──▌ LCL_ADDR long V23 tmp18 [+0]
[000231] ----------- arg2 in r8 └──▌ LCL_ADDR long V24 tmp19 [+0]After: fgMorphTree BB13, STMT00013 (before)
[000129] DACXG------ ▌ STORE_LCL_VAR int V06 tmp1
[000037] -ACXG------ └──▌ CALL int System.Comparison`1[System.Collections.BigStruct]:Invoke(System.Collections.BigStruct,System.Collections.BigStruct):int:this
[000006] ----------- this ├──▌ LCL_VAR ref V01 arg1 (last use)
[000207] -A--------- arg1 ├──▌ COMMA struct
[000206] UA--------- │ ├──▌ STORE_LCL_FLD int V07 tmp2 [+12]
[000205] ----------- │ │ └──▌ LCL_VAR int V17 tmp12
[000107] ----------- │ └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V07 tmp2 (last use)
[000210] -A--------- arg2 └──▌ COMMA struct
[000209] UA--------- ├──▌ STORE_LCL_FLD int V08 tmp3 [+12]
[000208] ----------- │ └──▌ LCL_VAR int V18 tmp13
[000109] ----------- └──▌ LCL_VAR struct<System.Collections.BigStruct, 32> V08 tmp3 (last use)
Initializing arg info for 37.CALL:
Args for call [000037] CALL after AddFinalArgsAndDetermineABIInfo:
CallArg[[000006].LCL_VAR ref (By value), 1 reg: rcx, byteAlignment=8, wellKnown[ThisPointer]]
CallArg[[000207].COMMA struct (By ref), 1 reg: rdx, byteAlignment=8, isStruct]
CallArg[[000210].COMMA struct (By ref), 1 reg: r8, byteAlignment=8, isStruct]
Morphing args for 37.CALL:
Local V07 should not be enregistered because: it is address exposed
did not need to make outgoing copy for last use of V07
Local V08 should not be enregistered because: it is address exposed
did not need to make outgoing copy for last use of V08
Sorting the arguments:
Argument with 'side effect'...
[000006] -----+----- ▌ LCL_VAR ref V01 arg1 (last use)
lvaGrabTemp returning 23 (V23 tmp18) called for argument with side effect.
Evaluate to a temp:
[000226] DA--------- ▌ STORE_LCL_VAR ref V23 tmp18
[000006] -----+----- └──▌ LCL_VAR ref V01 arg1 (last use)
Register placement order: rcx rdx r8
Args for [000037].CALL after fgMorphArgs:
CallArg[[000227].LCL_VAR ref (By value), 1 reg: rcx, byteAlignment=8, isLate, evaluateEarly, isTmp, tmpNum=V23, processed, wellKnown[ThisPointer]]
CallArg[[000107].LCL_ADDR struct (By ref), 1 reg: rdx, byteAlignment=8, isLate, evaluateEarly, processed, isStruct]
CallArg[[000109].LCL_ADDR struct (By ref), 1 reg: r8, byteAlignment=8, isLate, evaluateEarly, processed, isStruct]
OutgoingArgsStackSize is 32
fgMorphTree BB13, STMT00013 (after)
[000129] DACXG+----- ▌ STORE_LCL_VAR int V06 tmp1
[000037] -ACXG+----- └──▌ CALL int System.Comparison`1[System.Collections.BigStruct]:Invoke(System.Collections.BigStruct,System.Collections.BigStruct):int:this
[000226] DA--------- this setup ├──▌ STORE_LCL_VAR ref V23 tmp18
[000006] -----+----- │ └──▌ LCL_VAR ref V01 arg1 (last use)
[000206] UA---+----- arg1 setup ├──▌ STORE_LCL_FLD int (AX) V07 tmp2 [+12]
[000205] -----+----- │ └──▌ LCL_VAR int V17 tmp12
[000209] UA---+----- arg2 setup ├──▌ STORE_LCL_FLD int (AX) V08 tmp3 [+12]
[000208] -----+----- │ └──▌ LCL_VAR int V18 tmp13
[000227] ----------- this in rcx ├──▌ LCL_VAR ref V23 tmp18
[000107] -----+----- arg1 in rdx ├──▌ LCL_ADDR long V07 tmp2 [+0]
[000109] -----+----- arg2 in r8 └──▌ LCL_ADDR long V08 tmp3 [+0] |
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This was referenced Jun 15, 2023
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/azp run runtime-coreclr jitstress, runtime-coreclr libraries-jitstress, Fuzzlyn |
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Azure Pipelines successfully started running 3 pipeline(s). |
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Subsumed by #87869 |
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Allow last-use copy omission to kick in when the argument is a comma (typically created by physical promotion).
Also handle this pattern in arg evaluation: avoid creating a new local for the COMMA(..., LCL_ADDR) created for this pattern. As part of this rename the "needs temp" terminology to "needs early evaluation" since these cases do not actually need or create a temp. There were other cases already where we did not create a temp (specifically handling of GT_MKREFANY), so the terminology was already a bit misleading.
Fix #87471