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[flang] Fix FIRToMemRef index computation for array_coor with slice and shape_shift (#189496)

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Use shift instead of sliceLb only when the array_coor has an explicit
slice (indicesAreFortran case). When the slice comes from an embox,
the indices are 1-based section indices and must subtract 1.
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khaki3 2026-03-31 12:09:43 -07:00 committed by GitHub
parent 8af44b7867
commit c6d770fece
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2 changed files with 37 additions and 9 deletions
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11
flang/lib/Optimizer/Transforms/FIRToMemRef.cpp
View File

@ -485,15 +485,16 @@ FIRToMemRef::getMemrefIndices(fir::ArrayCoorOp arrayCoorOp, Operation *memref,
Value sliceLb = isSliced ? sliceLbs[i] : shift;
// When the array_coor has an explicit slice with a shape_shift (i.e.
// non-default lower bounds), the indices are Fortran indices; subtract
// the slice lower bound to get 0-based memref indices. Otherwise (the
// slice comes from an embox, or the shape has no shift), the indices
// are 1-based section indices; subtract 1.
// non-default lower bounds), the indices are in the shape_shift
// coordinate space; subtract the lower bound (shift) to get 0-based
// memref indices. Otherwise (the slice comes from an embox, or the
// shape has no shift), the indices are 1-based section indices;
// subtract 1.
bool indicesAreFortran = isShifted && arrayCoorOp.getSlice() != nullptr;
Value indexAdjustment =
(isSliced && !indicesAreFortran)
? arith::ConstantIndexOp::create(rewriter, loc, 1)
: sliceLb;
: shift;
Value delta = arith::SubIOp::create(rewriter, loc, index, indexAdjustment);
Value scaled = arith::MulIOp::create(rewriter, loc, delta, stride);

35
flang/test/Transforms/FIRToMemRef/array-coor-slice-shift.mlir
View File

@ -1,8 +1,5 @@
// Verify fir.array_coor with explicit shape_shift and slice correctly
// computes 0-based memref indices when lower bounds are non-default.
// This pattern arises after inlining canonicalizes fir.embox+fir.array_coor
// into a single fir.array_coor with explicit shape and slice operands,
// where the indices become Fortran indices rather than 1-based section indices.
// computes 0-based memref indices.
//
// RUN: fir-opt %s --fir-to-memref --allow-unregistered-dialect | FileCheck %s
@ -47,3 +44,33 @@ func.func @array_coor_slice_shift_2d() {
fir.store %c1_i32 to %4 : !fir.ref<i32>
return
}
// A(1:6, 1:9) with section A(:, 2:4). (default lb=1, slice starts at 2)
// Index (1, 1) = lower bounds => memref indices must be (1, 0).
// The slice offset for dim 2 (sliceLb=2, shift=1 => offset=1) must be
// preserved, not cancelled out.
// CHECK-LABEL: func.func @array_coor_slice_shift_section
// CHECK: %[[C1:.*]] = arith.constant 1 : index
// CHECK: %[[C2:.*]] = arith.constant 2 : index
// The dim 2 offset = sliceLb - shift = 2 - 1 = 1:
// CHECK: arith.subi %[[C2]], %[[C1]] : index
// CHECK: memref.store
// CHECK-NOT: fir.array_coor
func.func @array_coor_slice_shift_section() {
%c1 = arith.constant 1 : index
%c2 = arith.constant 2 : index
%c4 = arith.constant 4 : index
%c6 = arith.constant 6 : index
%c9 = arith.constant 9 : index
%c1_i32 = arith.constant 1 : i32
%0 = fir.alloca !fir.array<6x9xi32> {bindc_name = "a", uniq_name = "_QFEa"}
%1 = fir.shape_shift %c1, %c6, %c1, %c9 : (index, index, index, index) -> !fir.shapeshift<2>
%2 = fir.declare %0(%1) {uniq_name = "_QFEa"} : (!fir.ref<!fir.array<6x9xi32>>, !fir.shapeshift<2>) -> !fir.ref<!fir.array<6x9xi32>>
// Slice: full range in dim 1, section 2:4 in dim 2.
%3 = fir.slice %c1, %c6, %c1, %c2, %c4, %c1 : (index, index, index, index, index, index) -> !fir.slice<2>
// Index (1, 1) in shape_shift space. Dim 2 slice starts at 2,
// so memref index for dim 2 must be (1-1)+(2-1) = 1, not 0.
%4 = fir.array_coor %2(%1) [%3] %c1, %c1 : (!fir.ref<!fir.array<6x9xi32>>, !fir.shapeshift<2>, !fir.slice<2>, index, index) -> !fir.ref<i32>
fir.store %c1_i32 to %4 : !fir.ref<i32>
return
}