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Fix dead store alias issue #2753

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Fix dead store alias issue #2753

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7bc42fa
Fix dead store alias issue
wsmoses Mar 19, 2026
25fb25a
fix
wsmoses Mar 19, 2026
13b0fbc
fix
wsmoses Mar 19, 2026
40a0955
fix
wsmoses Mar 19, 2026
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18 changes: 3 additions & 15 deletions enzyme/Enzyme/DiffeGradientUtils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1032,31 +1032,19 @@ void DiffeGradientUtils::addToInvertedPtrDiffe(Instruction *orig,

SmallVector<Metadata *, 1> scopeMD = {
getDerivativeAliasScope(origptr, idx)};
if (auto origValI = dyn_cast_or_null<Instruction>(origVal))
if (auto MD = origValI->getMetadata(LLVMContext::MD_alias_scope)) {
auto MDN = cast<MDNode>(MD);
for (auto &o : MDN->operands())
scopeMD.push_back(o);
}
auto scope = MDNode::get(LI->getContext(), scopeMD);
LI->setMetadata(LLVMContext::MD_alias_scope, scope);
st->setMetadata(LLVMContext::MD_alias_scope, scope);

SmallVector<Metadata *, 1> MDs;
for (ssize_t j = -1; j < getWidth(); j++) {
for (ssize_t j = -1; j < (ssize_t)getWidth(); j++) {
if (j != (ssize_t)idx)
MDs.push_back(getDerivativeAliasScope(origptr, j));
}
if (auto origValI = dyn_cast_or_null<Instruction>(origVal))
if (auto MD = origValI->getMetadata(LLVMContext::MD_noalias)) {
auto MDN = cast<MDNode>(MD);
for (auto &o : MDN->operands())
MDs.push_back(o);
}
idx++;
auto noscope = MDNode::get(ptr->getContext(), MDs);
auto noscope = MDNode::get(LI->getContext(), MDs);
LI->setMetadata(LLVMContext::MD_noalias, noscope);
st->setMetadata(LLVMContext::MD_noalias, noscope);
idx++;

if (origVal && isa<Instruction>(origVal) && start == 0 &&
size == (DL.getTypeSizeInBits(origVal->getType()) + 7) / 8) {
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41 changes: 41 additions & 0 deletions enzyme/test/Enzyme/ReverseMode/alias-sret-correctness.ll
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@@ -0,0 +1,41 @@
; RUN: if [ %llvmver -ge 12 ]; then %opt < %s %newLoadEnzyme -enzyme-preopt=false -passes="enzyme,function(mem2reg,gvn,dse,simplifycfg)" -S | FileCheck %s; fi

define { double, double } @subcall(double %x) {
entry:
%m1 = fmul double %x, 2.0
%m2 = fmul double %x, 3.0
%res1 = insertvalue { double, double } undef, double %m1, 0
%res2 = insertvalue { double, double } %res1, double %m2, 1
ret { double, double } %res2
}

define double @caller(double %x, double* %p) {
entry:
%call = call { double, double } @subcall(double %x)
%val1 = extractvalue { double, double } %call, 0
%val2 = extractvalue { double, double } %call, 1

; Load carrying alias.scope
%l = load double, double* %p, align 8, !alias.scope !1

%res = fadd double %val1, %val2
%res2 = fadd double %res, %l
ret double %res2
}

!1 = !{!2}
!2 = distinct !{!2, !3, !"domain"}
!3 = distinct !{!3, !"domain"}

define void @test_diff(double %x, double* %p, double* %dp) {
call void (...) @__enzyme_autodiff(i8* bitcast (double (double, double*)* @caller to i8*), double %x, double* %p, double* %dp)
ret void
}

declare void @__enzyme_autodiff(...)

; CHECK: define internal { double } @diffecaller
; CHECK: %[[gep:.+]] = getelementptr inbounds { double, double }, { double, double }* %"call'de", i32 0, i32 1
; CHECK: %[[load:.+]] = load double, double* %[[gep]], align 8
; CHECK: %[[add:.+]] = fadd fast double %[[load]], %{{.+}}
; CHECK-NEXT: store double %[[add]], double* %[[gep]], align 8{{$}}
53 changes: 53 additions & 0 deletions enzyme/test/Enzyme/ReverseMode/alias-sret-ptr.ll
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@@ -0,0 +1,53 @@
; RUN: %opt < %s %newLoadEnzyme -enzyme-preopt=false -passes="enzyme,function(mem2reg,gvn,dse)" -S | FileCheck %s

; Subcall takes a pointer output to mimic Array return in memory
define void @subcall(double* %out, double %x) {
entry:
%m1 = fmul double %x, 2.0
%m2 = fmul double %x, 3.0
store double %m1, double* %out, align 8
%gep = getelementptr inbounds double, double* %out, i64 1
store double %m2, double* %gep, align 8
ret void
}

define double @caller(double %x, double* %p) {
entry:
%call_out = alloca double, i64 2, align 8
call void @subcall(double* %call_out, double %x)

%val1 = load double, double* %call_out, align 8
%gep = getelementptr inbounds double, double* %call_out, i64 1
%val2 = load double, double* %gep, align 8

; Load carrying alias.scope
%l = load double, double* %p, align 8, !alias.scope !1

%res = fadd double %val1, %val2
%res2 = fadd double %res, %l
ret double %res2
}

!1 = !{!2}
!2 = distinct !{!2, !3, !"domain"}
!3 = distinct !{!3, !"domain"}

define void @test_diff(double %x, double* %p, double* %dp) {
call void (...) @__enzyme_autodiff(i8* bitcast (double (double, double*)* @caller to i8*), double %x, double* %p, double* %dp)
ret void
}

declare void @__enzyme_autodiff(...)

; CHECK: define internal { double } @diffecaller(double %x, double* nocapture readonly %p, double* nocapture %"p'", double %differeturn)
; CHECK-NEXT: entry:
; CHECK-NEXT: %"call_out'ipa" = alloca double, i64 2, align 8
; CHECK-NEXT: %"gep'ipg" = getelementptr inbounds double, double* %"call_out'ipa", i64 1
; CHECK-NEXT: %[[loadP:.+]] = load double, double* %"p'", align 8, !alias.scope ![[scopeP:[0-9]+]], !noalias ![[noaliasP:[0-9]+]]
; CHECK-NEXT: %[[addP:.+]] = fadd fast double %[[loadP]], %differeturn
; CHECK-NEXT: store double %[[addP]], double* %"p'", align 8, !alias.scope ![[scopeP]], !noalias ![[noaliasP]]
; CHECK-NEXT: store double %differeturn, double* %"gep'ipg", align 8, !alias.scope ![[scopeS:[0-9]+]], !noalias ![[noaliasS:[0-9]+]]
; CHECK-NEXT: store double %differeturn, double* %"call_out'ipa", align 8, !alias.scope ![[scopeS]], !noalias ![[noaliasS]]

; CHECK: ![[scopeS]] = !{![[shadow_node:[0-9]+]]}
; CHECK: ![[shadow_node]] = distinct !{![[shadow_node]], !{{[0-9]+}}, !"shadow_0"}
51 changes: 51 additions & 0 deletions enzyme/test/Enzyme/ReverseMode/alias-sret.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,51 @@
; RUN: if [ %llvmver -ge 12 ]; then %opt < %s %newLoadEnzyme -enzyme-preopt=false -passes="enzyme,function(mem2reg)" -S | FileCheck %s; fi

define { double, double } @subcall(double %x) {
entry:
%m1 = fmul double %x, 2.0
%m2 = fmul double %x, 3.0
%res1 = insertvalue { double, double } undef, double %m1, 0
%res2 = insertvalue { double, double } %res1, double %m2, 1
ret { double, double } %res2
}

define double @caller(double %x, double* %p) {
entry:
%call = call { double, double } @subcall(double %x)
%val1 = extractvalue { double, double } %call, 0
%val2 = extractvalue { double, double } %call, 1
%l = load double, double* %p, !alias.scope !1
%res = fadd double %val1, %val2
%res2 = fadd double %res, %l
ret double %res2
}

!1 = !{!2}
!2 = distinct !{!2, !3, !"domain"}
!3 = distinct !{!3, !"domain"}

define void @test_diff(double %x, double* %p, double* %dp) {
call void (...) @__enzyme_autodiff(i8* bitcast (double (double, double*)* @caller to i8*), double %x, double* %p, double* %dp)
ret void
}

declare void @__enzyme_autodiff(...)

; CHECK: define internal { double } @diffecaller(double %x, double* nocapture readonly %p, double* nocapture %"p'", double %differeturn)
; CHECK-NEXT: entry:
; CHECK-NEXT: %"call'de" = alloca { double, double }, align 8
; CHECK-NEXT: store { double, double } zeroinitializer, { double, double }* %"call'de", align 8
; CHECK-NEXT: br label %invertentry

; CHECK: invertentry:
; CHECK-NEXT: %[[add0:.+]] = fadd fast double 0.000000e+00, %differeturn
; CHECK-NEXT: %[[add1:.+]] = fadd fast double 0.000000e+00, %differeturn
; CHECK-NEXT: %[[add2:.+]] = fadd fast double 0.000000e+00, %[[add0]]
; CHECK-NEXT: %[[add3:.+]] = fadd fast double 0.000000e+00, %[[add0]]
; CHECK-NEXT: %[[loadP:.+]] = load double, double* %"p'", align 8, !alias.scope ![[scopeP:[0-9]+]], !noalias ![[noaliasP:[0-9]+]]
; CHECK-NEXT: %[[addP:.+]] = fadd fast double %[[loadP]], %[[add1]]
; CHECK-NEXT: store double %[[addP]], double* %"p'", align 8, !alias.scope ![[scopeP]], !noalias ![[noaliasP]]
; CHECK-NEXT: %[[gepS:.+]] = getelementptr inbounds { double, double }, { double, double }* %"call'de", i32 0, i32 1
; CHECK-NEXT: %[[loadS:.+]] = load double, double* %[[gepS]], align 8
; CHECK-NEXT: %[[addS:.+]] = fadd fast double %[[loadS]], %[[add3]]
; CHECK-NEXT: store double %[[addS]], double* %[[gepS]], align 8{{$}}
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