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[Flang][Alias analysis] Fix alias analysis for omp private allocatable item #120243

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Jan 2, 2025
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[Flang][Alias analysis] Fix alias analysis for omp private allocatable item #120243

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[Flang][Alias analysis] Fix alias analysis for omp private
DominikAdamski Dec 17, 2024
07d4bb8
Applied remarks
DominikAdamski Dec 19, 2024
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36 changes: 14 additions & 22 deletions flang/lib/Optimizer/Analysis/AliasAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -505,30 +505,17 @@ getAttrsFromVariable(fir::FortranVariableOpInterface var) {
}

template <typename OMPTypeOp, typename DeclTypeOp>
static Value getPrivateArg(omp::BlockArgOpenMPOpInterface &argIface,
OMPTypeOp &op, DeclTypeOp &declOp) {
Value privateArg;
static bool isPrivateArg(omp::BlockArgOpenMPOpInterface &argIface,
OMPTypeOp &op, DeclTypeOp &declOp) {
if (!op.getPrivateSyms().has_value())
return privateArg;
return false;
for (auto [opSym, blockArg] :
llvm::zip_equal(*op.getPrivateSyms(), argIface.getPrivateBlockArgs())) {
if (blockArg == declOp.getMemref()) {
omp::PrivateClauseOp privateOp =
SymbolTable::lookupNearestSymbolFrom<omp::PrivateClauseOp>(
op, cast<SymbolRefAttr>(opSym));
privateOp.walk([&](omp::YieldOp yieldOp) {
// TODO Extend alias analysis if omp.yield points to
// block argument value
if (!yieldOp.getResults()[0].getDefiningOp())
return;
llvm::TypeSwitch<Operation *>(yieldOp.getResults()[0].getDefiningOp())
.template Case<fir::DeclareOp, hlfir::DeclareOp>(
[&](auto declOp) { privateArg = declOp.getMemref(); });
});
return privateArg;
return true;
}
}
return privateArg;
return false;
}

AliasAnalysis::Source AliasAnalysis::getSource(mlir::Value v,
Expand Down Expand Up @@ -630,6 +617,7 @@ AliasAnalysis::Source AliasAnalysis::getSource(mlir::Value v,
breakFromLoop = true;
})
.Case<hlfir::DeclareOp, fir::DeclareOp>([&](auto op) {
bool isPrivateItem = false;
if (omp::BlockArgOpenMPOpInterface argIface =
dyn_cast<omp::BlockArgOpenMPOpInterface>(op->getParentOp())) {
Value ompValArg;
Expand All @@ -643,19 +631,18 @@ AliasAnalysis::Source AliasAnalysis::getSource(mlir::Value v,
omp::MapInfoOp mapInfo =
llvm::cast<omp::MapInfoOp>(opArg.getDefiningOp());
ompValArg = mapInfo.getVarPtr();
break;
return;
}
}
// If given operation does not reflect mapping item,
// check private clause
if (!ompValArg)
ompValArg = getPrivateArg(argIface, targetOp, op);
isPrivateItem = isPrivateArg(argIface, targetOp, op);
})
.template Case<omp::DistributeOp, omp::ParallelOp,
omp::SectionsOp, omp::SimdOp, omp::SingleOp,
omp::TaskloopOp, omp::TaskOp, omp::WsloopOp>(
[&](auto privateOp) {
ompValArg = getPrivateArg(argIface, privateOp, op);
isPrivateItem = isPrivateArg(argIface, privateOp, op);
});
if (ompValArg) {
v = ompValArg;
Expand Down Expand Up @@ -705,6 +692,11 @@ AliasAnalysis::Source AliasAnalysis::getSource(mlir::Value v,
} else {
instantiationPoint = op;
}
if (isPrivateItem) {
type = SourceKind::Allocate;
breakFromLoop = true;
return;
}
// TODO: Look for the fortran attributes present on the operation
// Track further through the operand
v = op.getMemref();
Expand Down
50 changes: 50 additions & 0 deletions flang/test/Analysis/AliasAnalysis/alias-analysis-omp-private-allocatable.mlir
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Original file line number Diff line number Diff line change
@@ -0,0 +1,50 @@
// Use --mlir-disable-threading so that the AA queries are serialized
// as well as its diagnostic output.
// RUN: fir-opt %s -pass-pipeline='builtin.module(func.func(test-fir-alias-analysis))' -split-input-file --mlir-disable-threading 2>&1 | FileCheck %s

// Fortran code before simplification:
// SUBROUTINE mysub(ns,ne)
// INTEGER :: n
// REAL(KIND=8), DIMENSION(:), allocatable :: ar1
// real(kind=8), dimension(20) :: ar2
// REAL(KIND=8), DIMENSION(20) :: d
//
//!$OMP parallel PRIVATE(ar1)
// d(1:1) = (/(DOT_PRODUCT(ar1(1:n), ar2(1:n)),n=1, 1)/)
//!$OMP END parallel
// END SUBROUTINE

// CHECK-LABEL: Testing : "testPrivateAllocatable"
// CHECK: ar2#0 <-> ar1#0: NoAlias
// CHECK: ar2#1 <-> ar1#0: NoAlias
// CHECK: ar2#0 <-> ar1#1: NoAlias
// CHECK: ar2#1 <-> ar1#1: NoAlias

omp.private {type = private} @_QFmysubEar1_private_ref_box_heap_Uxf64 : !fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>> alloc {
^bb0(%arg0: !fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>):
%0 = fir.alloca !fir.box<!fir.heap<!fir.array<?xf64>>> {bindc_name = "ar1", pinned, uniq_name = "_QFmysubEar1"}
%5:2 = hlfir.declare %0 {fortran_attrs = #fir.var_attrs<allocatable>, uniq_name = "_QFmysubEar1"} : (!fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>) -> (!fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>, !fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>)
omp.yield(%5#0 : !fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>)
} dealloc {
^bb0(%arg0: !fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>):
omp.yield
}
func.func @testPrivateAllocatable(%arg0: !fir.ref<i32> {fir.bindc_name = "ns"}, %arg1: !fir.ref<i32> {fir.bindc_name = "ne"}) {
%0 = fir.dummy_scope : !fir.dscope
%1 = fir.alloca !fir.box<!fir.heap<!fir.array<?xf64>>> {bindc_name = "ar1", uniq_name = "_QFmysubEar1"}
%2 = fir.zero_bits !fir.heap<!fir.array<?xf64>>
%c0 = arith.constant 0 : index
%3 = fir.shape %c0 : (index) -> !fir.shape<1>
%4 = fir.embox %2(%3) : (!fir.heap<!fir.array<?xf64>>, !fir.shape<1>) -> !fir.box<!fir.heap<!fir.array<?xf64>>>
fir.store %4 to %1 : !fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>
%5:2 = hlfir.declare %1 {fortran_attrs = #fir.var_attrs<allocatable>, uniq_name = "_QFmysubEar1"} : (!fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>) -> (!fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>, !fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>)
%c20 = arith.constant 20 : index
%6 = fir.alloca !fir.array<20xf64> {bindc_name = "ar2", uniq_name = "_QFmysubEar2"}
%7 = fir.shape %c20 : (index) -> !fir.shape<1>
%8:2 = hlfir.declare %6(%7) {uniq_name = "_QFmysubEar2", test.ptr="ar2" } : (!fir.ref<!fir.array<20xf64>>, !fir.shape<1>) -> (!fir.ref<!fir.array<20xf64>>, !fir.ref<!fir.array<20xf64>>)
omp.parallel private(@_QFmysubEar1_private_ref_box_heap_Uxf64 %5#0 -> %arg2 : !fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>) {
%20:2 = hlfir.declare %arg2 {fortran_attrs = #fir.var_attrs<allocatable>, uniq_name = "_QFmysubEar1", test.ptr = "ar1"} : (!fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>) -> (!fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>, !fir.ref<!fir.box<!fir.heap<!fir.array<?xf64>>>>)
omp.terminator
}
return
}
Comment on lines +32 to +50
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Do we need this func.func code for the test to work? Or is the omp.private op only required?

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Hi,
We need code inside func.fun for the test to work.

Detailed explanation:
fun.func MLIR code contains two operations:
%20:2 = hlfir.declare %arg2 {fortran_attrs = #fir.var_attrs<allocatable>, uniq_name = "_QFmysubEar1", test.ptr = "ar1"}
and:
%8:2 = hlfir.declare %6(%7) {uniq_name = "_QFmysubEar2", test.ptr="ar2" }
These two operations contain manually added test.ptr attributes. test.ptr attributes are required for testing alias analysis. If we don't attach them, we don't see the console output of alias analysis (i.e.: ar2#0 <-> ar1#0: NoAlias )

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