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Experiment: annotate hot paths on LLVM #1384

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b6f26ef
Assume uniqueness of RC (= 0)
jiribenes Apr 21, 2026
a372bef
Annotate pure functions in RTS
jiribenes Apr 21, 2026
25f5301
Annotate 'nofree' on sharers
jiribenes Apr 21, 2026
5d86d02
Annotate 'nounwind' + 'invariant.load' on erasers
jiribenes Apr 21, 2026
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47 changes: 26 additions & 21 deletions libraries/llvm/rts.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,7 @@ declare double @tan(double)
declare void @print(i64)
declare void @exit(i64)
declare void @llvm.assume(i1)
declare i64 @llvm.expect.i64(i64, i64)


; Prompts
Expand Down Expand Up @@ -153,7 +154,7 @@ define private %Environment @objectEnvironment(%Object %object) alwaysinline {
ret %Environment %environment
}

define private void @shareObject(%Object %object) alwaysinline {
define private void @shareObject(%Object %object) alwaysinline nounwind nosync nofree {
%isNull = icmp eq %Object %object, null
br i1 %isNull, label %done, label %next

Expand All @@ -168,26 +169,27 @@ define private void @shareObject(%Object %object) alwaysinline {
ret void
}

define void @sharePositive(%Pos %val) alwaysinline {
define void @sharePositive(%Pos %val) alwaysinline nounwind nosync nofree {
%object = extractvalue %Pos %val, 1
tail call void @shareObject(%Object %object)
ret void
}

define void @shareNegative(%Neg %val) alwaysinline {
define void @shareNegative(%Neg %val) alwaysinline nounwind nosync nofree {
%object = extractvalue %Neg %val, 1
tail call void @shareObject(%Object %object)
ret void
}

define private void @eraseObject(%Object %object) alwaysinline {
define private void @eraseObject(%Object %object) alwaysinline nounwind nosync {
%isNull = icmp eq %Object %object, null
br i1 %isNull, label %done, label %next

next:
%objectReferenceCount = getelementptr %Header, ptr %object, i64 0, i32 0
%referenceCount = load %ReferenceCount, ptr %objectReferenceCount, !alias.scope !14, !noalias !24
switch %ReferenceCount %referenceCount, label %decr [%ReferenceCount 0, label %free]
%expectedRC = call i64 @llvm.expect.i64(i64 %referenceCount, i64 0) ; assume uniqueness
switch %ReferenceCount %expectedRC, label %decr [%ReferenceCount 0, label %free]

decr:
%referenceCount.1 = sub %ReferenceCount %referenceCount, 1
Expand All @@ -196,7 +198,7 @@ define private void @eraseObject(%Object %object) alwaysinline {

free:
%objectEraser = getelementptr %Header, ptr %object, i64 0, i32 1
%eraser = load %Eraser, ptr %objectEraser, !alias.scope !14, !noalias !24
%eraser = load %Eraser, ptr %objectEraser, !alias.scope !14, !noalias !24, !invariant.load !{}
%environment = call %Environment @objectEnvironment(%Object %object)
call void %eraser(%Environment %environment)
call void @free(%Object %object)
Expand All @@ -206,13 +208,13 @@ define private void @eraseObject(%Object %object) alwaysinline {
ret void
}

define void @erasePositive(%Pos %val) alwaysinline {
define void @erasePositive(%Pos %val) alwaysinline nounwind nosync {
%object = extractvalue %Pos %val, 1
tail call void @eraseObject(%Object %object)
ret void
}

define void @eraseNegative(%Neg %val) alwaysinline {
define void @eraseNegative(%Neg %val) alwaysinline nounwind nosync {
%object = extractvalue %Neg %val, 1
tail call void @eraseObject(%Object %object)
ret void
Expand Down Expand Up @@ -322,7 +324,7 @@ define private %StackPointer @stackDeallocate(%Stack %stack, i64 %n) {
ret %StackPointer %newStackPointer
}

define private i64 @nextPowerOfTwo(i64 %x) {
define private i64 @nextPowerOfTwo(i64 %x) nounwind nosync willreturn readnone {
%leadingZeros = call i64 @llvm.ctlz.i64(i64 %x, i1 false)
%numBits = sub i64 64, %leadingZeros
%result = shl i64 1, %numBits
Expand Down Expand Up @@ -449,7 +451,8 @@ define private {%Resumption, %Stack} @shift(%Stack %stack, %Prompt %prompt) {
define private void @erasePrompt(%Prompt %prompt) alwaysinline {
%referenceCount_pointer = getelementptr %PromptValue, %Prompt %prompt, i64 0, i32 0
%referenceCount = load %ReferenceCount, ptr %referenceCount_pointer, !alias.scope !13, !noalias !23
switch %ReferenceCount %referenceCount, label %decrement [%ReferenceCount 0, label %free]
%expectedRC = call i64 @llvm.expect.i64(i64 %referenceCount, i64 0) ; assume uniqueness
switch %ReferenceCount %expectedRC, label %decrement [%ReferenceCount 0, label %free]

decrement:
%newReferenceCount = sub %ReferenceCount %referenceCount, 1
Expand Down Expand Up @@ -532,7 +535,8 @@ define private %Resumption @uniqueStack(%Resumption %resumption) alwaysinline {
entry:
%referenceCount_pointer = getelementptr %StackValue, %Resumption %resumption, i64 0, i32 0
%referenceCount = load %ReferenceCount, ptr %referenceCount_pointer, !alias.scope !11, !noalias !21
switch %ReferenceCount %referenceCount, label %copy [%ReferenceCount 0, label %done]
%expectedRC = call i64 @llvm.expect.i64(i64 %referenceCount, i64 0) ; assume uniqueness
switch %ReferenceCount %expectedRC, label %copy [%ReferenceCount 0, label %done]

done:
ret %Resumption %resumption
Expand Down Expand Up @@ -584,7 +588,8 @@ define void @shareResumption(%Resumption %resumption) alwaysinline {
define void @eraseResumption(%Resumption %resumption) alwaysinline {
%referenceCount_pointer = getelementptr %StackValue, %Resumption %resumption, i64 0, i32 0
%referenceCount = load %ReferenceCount, ptr %referenceCount_pointer, !alias.scope !11, !noalias !21
switch %ReferenceCount %referenceCount, label %decr [%ReferenceCount 0, label %free]
%expectedRC = call i64 @llvm.expect.i64(i64 %referenceCount, i64 0) ; assume uniqueness
switch %ReferenceCount %expectedRC, label %decr [%ReferenceCount 0, label %free]

decr:
%referenceCount.1 = sub %ReferenceCount %referenceCount, 1
Expand Down Expand Up @@ -740,7 +745,7 @@ define ccc void @run_Pos(%Pos %boxed, %Pos %argument) {
}


define ccc %Pos @coerceNegPos(%Neg %neg) {
define ccc %Pos @coerceNegPos(%Neg %neg) nounwind nosync willreturn readnone {
%arrayPointer = extractvalue %Neg %neg, 0
%object = extractvalue %Neg %neg, 1
%tagValue = ptrtoint ptr %arrayPointer to i64
Expand All @@ -749,7 +754,7 @@ define ccc %Pos @coerceNegPos(%Neg %neg) {
ret %Pos %boxed2
}

define ccc %Neg @coercePosNeg(%Pos %pos) {
define ccc %Neg @coercePosNeg(%Pos %pos) nounwind nosync willreturn readnone {
%tagValue = extractvalue %Pos %pos, 0
%object = extractvalue %Pos %pos, 1
%arrayPointer = inttoptr i64 %tagValue to ptr
Expand All @@ -758,38 +763,38 @@ define ccc %Neg @coercePosNeg(%Pos %pos) {
ret %Neg %unboxed2
}

define ccc %Pos @coerceIntPos(%Int %input) {
define ccc %Pos @coerceIntPos(%Int %input) nounwind nosync willreturn readnone {
%boxed1 = insertvalue %Pos zeroinitializer, i64 %input, 0
%boxed2 = insertvalue %Pos %boxed1, %Object null, 1
ret %Pos %boxed2
}

define ccc %Int @coercePosInt(%Pos %input) {
define ccc %Int @coercePosInt(%Pos %input) nounwind nosync willreturn readnone {
%unboxed = extractvalue %Pos %input, 0
ret %Int %unboxed
}

define ccc %Pos @coerceBytePos(%Byte %input) {
define ccc %Pos @coerceBytePos(%Byte %input) nounwind nosync willreturn readnone {
%extended = sext i8 %input to i64
%boxed1 = insertvalue %Pos zeroinitializer, i64 %extended, 0
%boxed2 = insertvalue %Pos %boxed1, %Object null, 1
ret %Pos %boxed2
}

define ccc %Byte @coercePosByte(%Pos %input) {
define ccc %Byte @coercePosByte(%Pos %input) nounwind nosync willreturn readnone {
%unboxed = extractvalue %Pos %input, 0
%truncated = trunc i64 %unboxed to i8
ret i8 %truncated
}

define ccc %Pos @coerceDoublePos(%Double %input) {
define ccc %Pos @coerceDoublePos(%Double %input) nounwind nosync willreturn readnone {
%number = bitcast double %input to i64
%boxed1 = insertvalue %Pos zeroinitializer, i64 %number, 0
%boxed2 = insertvalue %Pos %boxed1, %Object null, 1
ret %Pos %boxed2
}

define ccc %Double @coercePosDouble(%Pos %input) {
define ccc %Double @coercePosDouble(%Pos %input) nounwind nosync willreturn readnone {
%unboxed = extractvalue %Pos %input, 0
%d = bitcast i64 %unboxed to double
ret %Double %d
Expand Down Expand Up @@ -817,4 +822,4 @@ define ccc %Double @coercePosDouble(%Pos %input) {
!22 = !{!1, !3, !4, !5} ; not stackPointer
!23 = !{!1, !2, !4, !5} ; not prompt
!24 = !{!1, !2, !3, !5} ; not object
!25 = !{!1, !2, !3, !4 } ; not vtable
!25 = !{!1, !2, !3, !4 } ; not vtable
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