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[flang][OpenMP] Support parallel loop construct. (#127588)

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Extends support for the `loop` directive by adding support for `parallel
loop` combined directive.

Parent PR: #127489. Only the latest commit is relevant.
This commit is contained in:
Kareem Ergawy 2025-02-21 16:26:19 +01:00 committed by GitHub
parent 34167f9966
commit 3ce2a7dc32
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GPG Key ID: B5690EEEBB952194
4 changed files with 70 additions and 39 deletions
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27
flang/lib/Optimizer/OpenMP/GenericLoopConversion.cpp
View File

@ -52,8 +52,7 @@ public:
rewriteStandaloneLoop(loopOp, rewriter);
break;
case GenericLoopCombinedInfo::ParallelLoop:
llvm_unreachable(
"not yet implemented: Combined `parallel loop` directive");
rewriteToWsloop(loopOp, rewriter);
break;
case GenericLoopCombinedInfo::TeamsLoop:
if (teamsLoopCanBeParallelFor(loopOp))
@ -69,31 +68,12 @@ public:
static mlir::LogicalResult
checkLoopConversionSupportStatus(mlir::omp::LoopOp loopOp) {
GenericLoopCombinedInfo combinedInfo = findGenericLoopCombineInfo(loopOp);
switch (combinedInfo) {
case GenericLoopCombinedInfo::Standalone:
break;
case GenericLoopCombinedInfo::ParallelLoop:
return loopOp.emitError(
"not yet implemented: Combined `parallel loop` directive");
case GenericLoopCombinedInfo::TeamsLoop:
break;
}
auto todo = [&loopOp](mlir::StringRef clauseName) {
return loopOp.emitError()
<< "not yet implemented: Unhandled clause " << clauseName << " in "
<< loopOp->getName() << " operation";
};
// For `loop` and `teams loop` directives, `bind` is supported.
// Additionally, for `teams loop`, semantic checking verifies that the
// `bind` clause modifier is `teams`, so no need to check this here again.
if (combinedInfo == GenericLoopCombinedInfo::ParallelLoop &&
loopOp.getBindKind())
return todo("bind");
if (loopOp.getOrder())
return todo("order");
@ -147,8 +127,9 @@ private:
mlir::omp::ClauseBindKind::Parallel)
return mlir::WalkResult::interrupt();
// TODO check for combined `parallel loop` when we support
// it.
if (combinedInfo == GenericLoopCombinedInfo::ParallelLoop)
return mlir::WalkResult::interrupt();
} else if (auto callOp =
mlir::dyn_cast<mlir::CallOpInterface>(nestedOp)) {
// Calls to non-OpenMP API runtime functions inhibits

33
flang/test/Lower/OpenMP/loop-directive.f90
View File

@ -261,3 +261,36 @@ subroutine teams_loop_can_be_parallel_for
tid = omp_get_thread_num()
END DO
end subroutine
! CHECK-LABEL: func.func @_QPteams_loop_cannot_be_parallel_for_4
subroutine teams_loop_cannot_be_parallel_for_4
implicit none
integer :: iter, iter2, tid, val(20)
! CHECK: omp.teams {
! Verify the outer `loop` directive was mapped to only `distribute`.
! CHECK-NOT: omp.parallel {{.*}}
! CHECK: omp.distribute {{.*}} {
! CHECK-NEXT: omp.loop_nest {{.*}} {
! Verify the inner `loop` directive was mapped to a worksharing loop.
! CHECK: omp.wsloop {{.*}} {
! CHECK: omp.loop_nest {{.*}} {
! CHECK: }
! CHECK: }
! CHECK: }
! CHECK: }
! CHECK: }
!$omp target teams loop map(tofrom:val)
DO iter = 1, 5
!$omp parallel
!$omp loop
DO iter2 = 1, 5
val(iter+iter2) = iter+iter2
END DO
!$omp end parallel
END DO
end subroutine

16
flang/test/Transforms/generic-loop-rewriting-todo.mlir
View File

@ -1,21 +1,5 @@
// RUN: fir-opt --omp-generic-loop-conversion -verify-diagnostics %s
func.func @_QPparallel_loop() {
omp.parallel {
%c0 = arith.constant 0 : i32
%c10 = arith.constant 10 : i32
%c1 = arith.constant 1 : i32
// expected-error@below {{not yet implemented: Combined `parallel loop` directive}}
omp.loop {
omp.loop_nest (%arg3) : i32 = (%c0) to (%c10) inclusive step (%c1) {
omp.yield
}
}
omp.terminator
}
return
}
omp.declare_reduction @add_reduction_i32 : i32 init {
^bb0(%arg0: i32):
%c0_i32 = arith.constant 0 : i32

33
flang/test/Transforms/generic-loop-rewriting.mlir
View File

@ -45,3 +45,36 @@ func.func @_QPteams_loop() {
// CHECK: }
// CHECK: }
// CHECK: }
func.func @_QPparallel_loop() {
%i = fir.alloca i32
omp.parallel {
%c0 = arith.constant 0 : i32
%c10 = arith.constant 10 : i32
%c1 = arith.constant 1 : i32
omp.loop private(@_QFteams_loopEi_private_i32 %i -> %arg2 : !fir.ref<i32>) {
omp.loop_nest (%arg3) : i32 = (%c0) to (%c10) inclusive step (%c1) {
fir.store %arg3 to %arg2 : !fir.ref<i32>
omp.yield
}
}
omp.terminator
}
return
}
// CHECK-LABEL: func.func @_QPparallel_loop
// CHECK: %[[I:.*]] = fir.alloca i32
// CHECK: omp.parallel {
// CHECK: %[[LB:.*]] = arith.constant 0 : i32
// CHECK: %[[UB:.*]] = arith.constant 10 : i32
// CHECK: %[[STEP:.*]] = arith.constant 1 : i32
// CHECK: omp.wsloop private(@{{.*}} %[[I]]
// CHECK-SAME: -> %[[I_PRIV_ARG:[^[:space:]]+]] : !fir.ref<i32>) {
// CHECK: omp.loop_nest (%{{.*}}) : i32 =
// CHECK-SAME: (%[[LB]]) to (%[[UB]]) inclusive step (%[[STEP]]) {
// CHECK: fir.store %{{.*}} to %[[I_PRIV_ARG]] : !fir.ref<i32>
// CHECK: }
// CHECK: }
// CHECK: }