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[flang][lowering] delay stack save/restor emission in elemental calls #109142

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Merged
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Sep 19, 2024
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[flang][lowering] delay stack save/restor emission in elemental calls #109142

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6 changes: 5 additions & 1 deletion flang/lib/Lower/ConvertCall.cpp
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Expand Up @@ -366,7 +366,11 @@ std::pair<fir::ExtendedValue, bool> Fortran::lower::genCallOpAndResult(
resultLengths = lengths;
}

if (!extents.empty() || !lengths.empty()) {
if ((!extents.empty() || !lengths.empty()) && !isElemental) {
// Note: in the elemental context, the alloca ownership inside the
// elemental region is implicit, and later pass in lowering (stack
// reclaim) fir.do_loop will be in charge of emitting any stack
// save/restore if needed.
auto *bldr = &converter.getFirOpBuilder();
mlir::Value sp = bldr->genStackSave(loc);
stmtCtx.attachCleanup(
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2 changes: 0 additions & 2 deletions flang/test/Lower/HLFIR/elemental-array-ops.f90
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Expand Up @@ -182,12 +182,10 @@ end subroutine char_return
! CHECK: %[[VAL_23:.*]] = arith.constant 0 : index
! CHECK: %[[VAL_24:.*]] = arith.cmpi sgt, %[[VAL_22]], %[[VAL_23]] : index
! CHECK: %[[VAL_25:.*]] = arith.select %[[VAL_24]], %[[VAL_22]], %[[VAL_23]] : index
! CHECK: %[[VAL_26:.*]] = llvm.intr.stacksave : !llvm.ptr
! CHECK: %[[VAL_27:.*]] = fir.call @_QPcallee(%[[VAL_2]], %[[VAL_25]], %[[VAL_20]]) fastmath<contract> : (!fir.ref<!fir.char<1,3>>, index, !fir.boxchar<1>) -> !fir.boxchar<1>
! CHECK: %[[VAL_28:.*]]:2 = hlfir.declare %[[VAL_2]] typeparams %[[VAL_25]] {uniq_name = ".tmp.func_result"} : (!fir.ref<!fir.char<1,3>>, index) -> (!fir.ref<!fir.char<1,3>>, !fir.ref<!fir.char<1,3>>)
! CHECK: %[[MustFree:.*]] = arith.constant false
! CHECK: %[[ResultTemp:.*]] = hlfir.as_expr %[[VAL_28]]#0 move %[[MustFree]] : (!fir.ref<!fir.char<1,3>>, i1) -> !hlfir.expr<!fir.char<1,3>>
! CHECK: llvm.intr.stackrestore %[[VAL_26]] : !llvm.ptr
! CHECK: hlfir.yield_element %[[ResultTemp]] : !hlfir.expr<!fir.char<1,3>>
! CHECK: }
! CHECK: %[[VAL_29:.*]] = arith.constant 0 : index
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22 changes: 22 additions & 0 deletions flang/test/Lower/HLFIR/elemental-user-procedure-stacksave.f90
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@@ -0,0 +1,22 @@
! Check that stack save and restore needed for elemental function result
! allocation inside loops are not emitted directly in lowering, but inserted if
! needed in the stack-reclaim pass.

! RUN: %flang_fc1 -emit-hlfir %s -o - | FileCheck %s --check-prefix=CHECK-HLFIR
! RUN: %flang_fc1 -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK-LLVM
subroutine foo(c1, c2)
character(*), dimension(100) :: c1, c2
interface
elemental pure function func(c)
character(*), intent(in) :: c
character(len(c)) :: func
end function
end interface
c1 = func(c2)
end subroutine

! CHECK-HLFIR-NOT: stacksave
! CHECK: return

! CHECK-LLVM: stacksave
! CHECK-LLVM: stackrestore
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