JIT: Allow sharing call temps within statements by jakobbotsch · Pull Request #79574 · dotnet/runtime

jakobbotsch · 2022-12-12T23:02:21Z

fgMakeOutgoingArgCopy has a hashset of shared temps that it uses before creating a new temp. However, this hash set is reset only at new statements which can cause regressions when forward sub moves several calls into the same statement.

This adds support to allow the temps to be shared also within the same statement. To do this we must take care not to share temps that have overlapping lifetimes.

This fixes a regression seen in #79346.

fgMakeOutgoingArgCopy has a hashset of shared temps that it uses before creating a new temp. However, this hash set is reset only at new statements which can cause regressions when forward sub moves several calls into the same statement. This adds support to allow the temps to be shared also within the same statement. To do this we must take care not to share temps that have overlapping lifetimes.

ghost · 2022-12-12T23:02:36Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
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Issue Details

fgMakeOutgoingArgCopy has a hashset of shared temps that it uses before creating a new temp. However, this hash set is reset only at new statements which can cause regressions when forward sub moves several calls into the same statement.

This adds support to allow the temps to be shared also within the same statement. To do this we must take care not to share temps that have overlapping lifetimes.

This fixes a regression seen in #79346.

Author:	jakobbotsch
Assignees:	-
Labels:	`area-CodeGen-coreclr`
Milestone:	-

The macro expands to multiple loops so "break" does not do what would be expected.

jakobbotsch · 2022-12-13T11:51:02Z

- tmp = (unsigned)lclNum;
- found = true;
- JITDUMP("reusing outgoing struct arg\n");
- break;


FOREACH_HBV_BIT_SET expands into 4 nested loops, so this break is not doing what is expected here.
I have removed the macros and turned it into a callback based function instead to make it harder to make the same mistake in the future.
I first tried turning it into an iterator but it was quite complex and hard to follow when the loops are flattened, so I went with the callback approach instead.

jakobbotsch · 2022-12-15T16:42:12Z

Diffs. I spot checked a few of the regressions and they are all happening when the previous break; wouldn't actually break, so we would continue and select another local. Selecting a different local sometimes results in having to use a larger encoding if that local is allocated further away from the stack pointer.

@@ -166,11 +166,11 @@
; V156 tmp131 [V156,T79] ( 2, 1 ) int -> r14 V82._length(offs=0x08) P-INDEP "field V82._length (fldOffset=0x8)"
;* V157 tmp132 [V157 ] ( 0, 0 ) struct (16) zero-ref "Promoted implicit byref"
;* V158 tmp133 [V158 ] ( 0, 0 ) struct (16) zero-ref "Promoted implicit byref"
-; V159 tmp134 [V159 ] ( 12, 12 ) struct (16) [rbp+78H] do-not-enreg[XSF] must-init addr-exposed "by-value struct argument"+; V159 tmp134 [V159 ] ( 18, 18 ) struct (16) [rbp+78H] do-not-enreg[XSF] must-init addr-exposed "by-value struct argument"
; V160 tmp135 [V160 ] ( 18, 18 ) struct (16) [rbp+68H] do-not-enreg[XSF] must-init addr-exposed "by-value struct argument"
; V161 tmp136 [V161,T41] ( 2, 2 ) ref -> rcx single-def "argument with side effect"
; V162 tmp137 [V162,T42] ( 2, 2 ) ref -> rcx single-def "argument with side effect"
-; V163 tmp138 [V163 ] ( 12, 12 ) struct (16) [rbp+58H] do-not-enreg[XSF] must-init addr-exposed "by-value struct argument"+; V163 tmp138 [V163 ] ( 6, 6 ) struct (16) [rbp+58H] do-not-enreg[XSF] must-init addr-exposed "by-value struct argument"
; V164 tmp139 [V164,T43] ( 2, 2 ) ref -> rcx single-def "argument with side effect"
; V165 tmp140 [V165,T44] ( 2, 2 ) ref -> rcx single-def "argument with side effect"
; V166 GsCookie [V166 ] ( 1, 1 ) long -> [rbp+00H] do-not-enreg[X] addr-exposed "GSSecurityCookie"
@@ -517,13 +517,13 @@ G_M30337_IG26:
call [<unknown method>]
mov ecx, dword ptr [rbp+54H]
call [System.Diagnostics.Debug:Assert(bool)]
- mov bword ptr [rbp+58H], rbx- mov dword ptr [rbp+60H], r14d+ mov bword ptr [rbp+78H], rbx+ mov dword ptr [rbp+80H], r14d
mov rbx, bword ptr [rbp+18H]
mov bword ptr [rbp+68H], rbx
mov r14d, dword ptr [rbp+8CH]
mov dword ptr [rbp+70H], r14d
- lea rcx, [rbp+58H]+ lea rcx, [rbp+78H]
lea rdx, [rbp+68H]
call [System.Numerics.BigIntegerCalculator:Square(System.ReadOnlySpan`1[uint],System.Span`1[uint])]
mov r12, gword ptr [rbp+40H]
@@ -538,7 +538,7 @@ G_M30337_IG26:
xor r8d, r8d
cmp dword ptr [rcx], ecx
call [<unknown method>]
- ;; size=162 bbWeight=0.50 PerfScore 19.50+ ;; size=165 bbWeight=0.50 PerfScore 19.50
G_M30337_IG27:
mov ecx, dword ptr [rbp+50H]
call [System.Diagnostics.Debug:Assert(bool)]
@@ -549,15 +549,15 @@ G_M30337_IG27:
not ecx
shr ecx, 31
call [System.Diagnostics.Debug:Assert(bool)]
- mov bword ptr [rbp+58H], r12+ mov bword ptr [rbp+78H], r12
mov r12d, dword ptr [rbp+88H]
- mov dword ptr [rbp+60H], r12d- mov bword ptr [rbp+78H], rsi- mov dword ptr [rbp+80H], r15d+ mov dword ptr [rbp+80H], r12d+ mov bword ptr [rbp+58H], rsi+ mov dword ptr [rbp+60H], r15d
mov bword ptr [rbp+68H], rbx
mov dword ptr [rbp+70H], r14d
- lea rcx, [rbp+58H]- lea rdx, [rbp+78H]+ lea rcx, [rbp+78H]+ lea rdx, [rbp+58H]
lea r8, [rbp+68H]
call [<unknown method>]
cmp r13d, edi
@@ -573,10 +573,10 @@ G_M30337_IG27:
call [System.Diagnostics.Debug:Assert(bool)]
mov bword ptr [rbp+68H], rsi
mov dword ptr [rbp+70H], edi
- mov bword ptr [rbp+58H], rbx- mov dword ptr [rbp+60H], r14d+ mov bword ptr [rbp+78H], rbx+ mov dword ptr [rbp+80H], r14d
lea rcx, [rbp+68H]
- lea rdx, [rbp+58H]+ lea rdx, [rbp+78H]
call [System.Numerics.BigIntegerCalculator:AddSelf(System.Span`1[uint],System.ReadOnlySpan`1[uint])]
mov rsi, gword ptr [rbp+38H]
test rsi, rsi
@@ -590,7 +590,7 @@ G_M30337_IG27:
xor r8d, r8d
cmp dword ptr [rcx], ecx
call [<unknown method>]
- ;; size=217 bbWeight=0.50 PerfScore 26.62+ ;; size=220 bbWeight=0.50 PerfScore 26.62
G_M30337_IG28:
mov rcx, 0xD1FFAB1E
cmp qword ptr [rbp], rcx
@@ -621,11 +621,11 @@ G_M30337_IG32:
int3 ;; size=6 bbWeight=0 PerfScore 0.00
-; Total bytes of code 1505, prolog size 68, PerfScore 575.98, instruction count 372, allocated bytes for code 1509 (MethodHash=b62d897e) for method System.Numerics.BigIntegerCalculator:Square(System.ReadOnlySpan`1[uint],System.Span`1[uint])+; Total bytes of code 1511, prolog size 68, PerfScore 576.58, instruction count 372, allocated bytes for code 1515 (MethodHash=b62d897e) for method System.Numerics.BigIntegerCalculator:Square(System.ReadOnlySpan`1[uint],System.Span`1[uint])

Notice that we have more references to the "lower-numbered" local now, but it is allocated in the local frame right around the offset where we stop being able to use the smaller encoding for accesses.

jakobbotsch · 2022-12-15T16:45:29Z

/azp run runtime-coreclr jitstress, runtime-coreclr libraries-jitstress

jakobbotsch · 2022-12-15T16:45:40Z

/azp run Fuzzlyn

azure-pipelines · 2022-12-15T16:45:53Z

Azure Pipelines successfully started running 1 pipeline(s).

azure-pipelines · 2022-12-15T16:45:54Z

Azure Pipelines successfully started running 2 pipeline(s).

jakobbotsch · 2022-12-15T16:47:27Z

cc @dotnet/jit-contrib PTAL @EgorBo

jakobbotsch · 2022-12-16T10:18:23Z

Stress failure is known. The Fuzzlyn failures were #79543.

jakobbotsch · 2023-01-03T09:13:30Z

Ping @EgorBo

jakobbotsch · 2023-01-04T23:09:53Z

Going to rerun the CI on this to get fresh diffs.

jakobbotsch · 2023-01-05T09:30:31Z

Diffs are the same as above, mostly some minor TP and CQ improvements, with a few regressions due to what I mentioned above.

ghost added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Dec 12, 2022

ghost assigned jakobbotsch Dec 12, 2022

build-analysisBot mentioned this pull request Dec 13, 2022
Tracking issue for CI build timeouts #76454
Closed

jakobbotsch added 2 commits December 13, 2022 12:45

Fix bit set iteration
93f87c1
The macro expands to multiple loops so "break" does not do what would be expected.

Remove static
696c2b7

jakobbotsch commented Dec 13, 2022
View reviewed changes

jakobbotsch mentioned this pull request Dec 13, 2022
JIT: Add a pass of early liveness and use it for forward sub and last-use copy elision for implicit byrefs #79346
Merged
10 tasks

jakobbotsch marked this pull request as ready for review December 15, 2022 16:46

jakobbotsch requested a review from EgorBo December 15, 2022 16:47

build-analysisBot mentioned this pull request Dec 15, 2022
Precondition failure: File has not had execution verified #79439
Closed

jakobbotsch closed this Jan 4, 2023

jakobbotsch reopened this Jan 4, 2023

EgorBo approved these changes Jan 5, 2023
View reviewed changes

jakobbotsch merged commit da54237 into dotnet:mainJan 5, 2023

jakobbotsch deleted the shared-temps-within-statements branch January 5, 2023 10:06

ghost locked as resolved and limited conversation to collaborators Feb 4, 2023

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JIT: Allow sharing call temps within statements - #79574

JIT: Allow sharing call temps within statements#79574
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