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Fix revert mode for memref.alloca #2826

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Fix revert mode for memref.alloca #2826

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3bfcc96
using scf.parallel+memref.store to zero out a memref
xys-syx May 13, 2026
d69009f
add test for memref.alloca
xys-syx May 13, 2026
ef3590a
revert
xys-syx May 14, 2026
435ee27
fmt
xys-syx May 14, 2026
759bfb5
revert
xys-syx May 20, 2026
7f88905
Revert "using scf.parallel+memref.store to zero out a memref"
xys-syx May 21, 2026
0222508
add guard to setInvertedPointer
xys-syx May 23, 2026
4cab90b
match linalg.fill
xys-syx May 23, 2026
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11 changes: 10 additions & 1 deletion enzyme/Enzyme/MLIR/Interfaces/GradientUtils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -223,8 +223,17 @@ void mlir::enzyme::MGradientUtils::setDiffe(mlir::Value val, mlir::Value toset,
}
assert(!isConstantValue(val));

bool isMutable = false;
if (auto iface = dyn_cast<AutoDiffTypeInterface>(val.getType()))
isMutable = iface.isMutable();

if (mode == DerivativeMode::ForwardMode ||
mode == DerivativeMode::ForwardModeSplit) {
mode == DerivativeMode::ForwardModeSplit || isMutable) {
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@vimarsh6739 vimarsh6739 May 21, 2026

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func.func @square(%x : memref<f64>){
     %y = memref.load %x[] : f64
     return %y
}

%out = enzyme.fwddiff dsquare(%x : memref<f64>, %dx : memref<f64>) {act = [enzyme_dup] ....}

In this case, the user provides the inverted Pointer right? We should ensure that we arent creating a shadow

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@xys-syx xys-syx May 23, 2026

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i have add a guard in setDiffe when val is mutable or intertedPointers[val] is not a placeholderop, we skip instead of rewriting it.

if (isMutable) {
auto existing = invertedPointers.lookupOrNull(val);
if (existing && !existing.getDefiningOp<enzyme::PlaceholderOp>())
return;
}
setInvertedPointer(val, toset);
}
/*
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62 changes: 62 additions & 0 deletions enzyme/test/MLIR/ReverseMode/alloca.mlir
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Original file line number Diff line number Diff line change
@@ -0,0 +1,62 @@
// RUN: %eopt --enzyme %s | FileCheck %s

func.func @foo_flat(%x : f64) -> f64 {
%buf = memref.alloca() : memref<f64>
memref.store %x, %buf[] : memref<f64>
%y = memref.load %buf[] : memref<f64>
return %y : f64
}

func.func @dfoo_flat(%x: f64, %dout : f64) -> f64 {
%dx = enzyme.autodiff @foo_flat(%x, %dout) {
activity = [#enzyme<activity enzyme_active>],
ret_activity = [#enzyme<activity enzyme_activenoneed>]
} : (f64, f64) -> (f64)
return %dx : f64
}

// CHECK-LABEL: func.func private @diffefoo_flat(
// CHECK-SAME: %[[X:[^,]+]]: f64,
// CHECK-SAME: %[[DOUT:[^)]+]]: f64) -> f64 {

// CHECK: %[[GX:.+]] = "enzyme.init"() : () -> !enzyme.Gradient<f64>
// CHECK: "enzyme.set"(%[[GX]], %{{.*}}) : (!enzyme.Gradient<f64>, f64) -> ()
// CHECK: %[[CS:.+]] = "enzyme.init"() : () -> !enzyme.Cache<memref<f64>>
// CHECK: %[[CL:.+]] = "enzyme.init"() : () -> !enzyme.Cache<memref<f64>>
// CHECK: %[[GY:.+]] = "enzyme.init"() : () -> !enzyme.Gradient<f64>
// CHECK: "enzyme.set"(%[[GY]], %{{.*}}) : (!enzyme.Gradient<f64>, f64) -> ()

// CHECK: %[[DBUF:.+]] = memref.alloca() : memref<f64>
// CHECK: %[[ZERO_INIT:.+]] = arith.constant 0.000000e+00 : f64
// CHECK: linalg.fill ins(%[[ZERO_INIT]] : f64) outs(%[[DBUF]] : memref<f64>)

// CHECK: %[[BUF:.+]] = memref.alloca() : memref<f64>
// CHECK: "enzyme.push"(%[[CS]], %[[DBUF]]) : (!enzyme.Cache<memref<f64>>, memref<f64>) -> ()
// CHECK: memref.store %[[X]], %[[BUF]][] : memref<f64>
// CHECK: "enzyme.push"(%[[CL]], %[[DBUF]]) : (!enzyme.Cache<memref<f64>>, memref<f64>) -> ()
// CHECK: memref.load %[[BUF]][] : memref<f64>
// CHECK: cf.br ^bb1
// CHECK: ^bb1:

// CHECK: %{{.+}} = "enzyme.get"(%[[GY]]) : (!enzyme.Gradient<f64>) -> f64
// CHECK: arith.addf %{{.+}}, %[[DOUT]] : f64
// CHECK: "enzyme.set"(%[[GY]], %{{.*}}) : (!enzyme.Gradient<f64>, f64) -> ()

// CHECK: %{{.+}} = "enzyme.get"(%[[GY]]) : (!enzyme.Gradient<f64>) -> f64
// CHECK: %[[POPL:.+]] = "enzyme.pop"(%[[CL]]) : (!enzyme.Cache<memref<f64>>) -> memref<f64>
// CHECK: memref.load %[[POPL]][] : memref<f64>
// CHECK: arith.addf
// CHECK: memref.store %{{.+}}, %[[POPL]][] : memref<f64>

// CHECK: %[[POPS:.+]] = "enzyme.pop"(%[[CS]]) : (!enzyme.Cache<memref<f64>>) -> memref<f64>
// CHECK: memref.load %[[POPS]][] : memref<f64>
// CHECK: %{{.+}} = "enzyme.get"(%[[GX]]) : (!enzyme.Gradient<f64>) -> f64
// CHECK: arith.addf
// CHECK: "enzyme.set"(%[[GX]], %{{.*}}) : (!enzyme.Gradient<f64>, f64) -> ()
// CHECK: %[[ZERO_CLEAR:.+]] = arith.constant 0.000000e+00 : f64
// CHECK: memref.store %[[ZERO_CLEAR]], %[[POPS]][] : memref<f64>

// CHECK: %{{.+}} = "enzyme.get"(%[[GX]]) : (!enzyme.Gradient<f64>) -> f64
// CHECK: return %{{.+}} : f64

// CHECK-NOT: enzyme.placeholder
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