From 3c1a4dc6318c3b619bfbe5ae88fb79282bc7a7d2 Mon Sep 17 00:00:00 2001 From: ergawy Date: Tue, 29 Oct 2024 04:44:20 -0500 Subject: [PATCH] [flang][MLIR] Hoist `do concurrent` nest bounds/step outside the nest If you have the following multi-range `do concurrent` loop: ```fortran do concurrent(i=1:n, j=1:bar(n*m, n/m)) a(i) = n end do ``` Currently, flang generates the following IR: ```mlir fir.do_loop %arg1 = %42 to %44 step %c1 unordered { ... %53:3 = hlfir.associate %49 {adapt.valuebyref} : (i32) -> (!fir.ref, !fir.ref, i1) %54:3 = hlfir.associate %52 {adapt.valuebyref} : (i32) -> (!fir.ref, !fir.ref, i1) %55 = fir.call @_QFPbar(%53#1, %54#1) fastmath : (!fir.ref, !fir.ref) -> i32 hlfir.end_associate %53#1, %53#2 : !fir.ref, i1 hlfir.end_associate %54#1, %54#2 : !fir.ref, i1 %56 = fir.convert %55 : (i32) -> index ... fir.do_loop %arg2 = %46 to %56 step %c1_4 unordered { ... } } ``` However, if `bar` is impure, then we have a direct violation of the standard: ``` C1143 A reference to an impure procedure shall not appear within a DO CONCURRENT construct. ``` Moreover, the standard describes the execution of `do concurrent` construct in multiple stages: ``` 11.1.7.4 Execution of a DO construct ... 11.1.7.4.2 DO CONCURRENT loop control The concurrent-limit and concurrent-step expressions in the concurrent-control-list are evaluated. ... 11.1.7.4.3 The execution cycle ... The block of a DO CONCURRENT construct is executed for every active combination of the index-name values. Each execution of the block is an iteration. The executions may occur in any order. ``` From the above 2 points, it seems to me that execution is divided in multiple consecutive stages: 11.1.7.4.2 is the stage where we evaluate all control expressions including the step and then 11.1.7.4.3 is the stage to execute the block of the concurrent loop itself using the combination of possible iteration values. --- flang/lib/Lower/Bridge.cpp | 41 ++++++++---- flang/test/Lower/do_concurrent.f90 | 102 +++++++++++++++++++++++++++++ 2 files changed, 132 insertions(+), 11 deletions(-) create mode 100644 flang/test/Lower/do_concurrent.f90 diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp index 877fe122265dd..0e3011e73902d 100644 --- a/flang/lib/Lower/Bridge.cpp +++ b/flang/lib/Lower/Bridge.cpp @@ -2131,18 +2131,37 @@ class FirConverter : public Fortran::lower::AbstractConverter { llvm::SmallVectorImpl &dirs) { assert(!incrementLoopNestInfo.empty() && "empty loop nest"); mlir::Location loc = toLocation(); + mlir::Operation *boundsAndStepIP = nullptr; + for (IncrementLoopInfo &info : incrementLoopNestInfo) { - info.loopVariable = - genLoopVariableAddress(loc, *info.loopVariableSym, info.isUnordered); - mlir::Value lowerValue = genControlValue(info.lowerExpr, info); - mlir::Value upperValue = genControlValue(info.upperExpr, info); - bool isConst = true; - mlir::Value stepValue = genControlValue( - info.stepExpr, info, info.isStructured() ? nullptr : &isConst); - // Use a temp variable for unstructured loops with non-const step. - if (!isConst) { - info.stepVariable = builder->createTemporary(loc, stepValue.getType()); - builder->create(loc, stepValue, info.stepVariable); + mlir::Value lowerValue; + mlir::Value upperValue; + mlir::Value stepValue; + + { + mlir::OpBuilder::InsertionGuard guard(*builder); + + // Set the IP before the first loop in the nest so that all nest bounds + // and step values are created outside the nest. + if (boundsAndStepIP) + builder->setInsertionPointAfter(boundsAndStepIP); + + info.loopVariable = genLoopVariableAddress(loc, *info.loopVariableSym, + info.isUnordered); + lowerValue = genControlValue(info.lowerExpr, info); + upperValue = genControlValue(info.upperExpr, info); + bool isConst = true; + stepValue = genControlValue(info.stepExpr, info, + info.isStructured() ? nullptr : &isConst); + boundsAndStepIP = stepValue.getDefiningOp(); + + // Use a temp variable for unstructured loops with non-const step. + if (!isConst) { + info.stepVariable = + builder->createTemporary(loc, stepValue.getType()); + boundsAndStepIP = + builder->create(loc, stepValue, info.stepVariable); + } } // Structured loop - generate fir.do_loop. diff --git a/flang/test/Lower/do_concurrent.f90 b/flang/test/Lower/do_concurrent.f90 new file mode 100644 index 0000000000000..ef93d2d6b035b --- /dev/null +++ b/flang/test/Lower/do_concurrent.f90 @@ -0,0 +1,102 @@ +! RUN: %flang_fc1 -emit-hlfir -o - %s | FileCheck %s + +! Simple tests for structured concurrent loops with loop-control. + +pure function bar(n, m) + implicit none + integer, intent(in) :: n, m + integer :: bar + bar = n + m +end function + +!CHECK-LABEL: sub1 +subroutine sub1(n) + implicit none + integer :: n, m, i, j, k + integer, dimension(n) :: a +!CHECK: %[[LB1:.*]] = arith.constant 1 : i32 +!CHECK: %[[LB1_CVT:.*]] = fir.convert %[[LB1]] : (i32) -> index +!CHECK: %[[UB1:.*]] = fir.load %{{.*}}#0 : !fir.ref +!CHECK: %[[UB1_CVT:.*]] = fir.convert %[[UB1]] : (i32) -> index + +!CHECK: %[[LB2:.*]] = arith.constant 1 : i32 +!CHECK: %[[LB2_CVT:.*]] = fir.convert %[[LB2]] : (i32) -> index +!CHECK: %[[UB2:.*]] = fir.call @_QPbar(%{{.*}}, %{{.*}}) proc_attrs fastmath : (!fir.ref, !fir.ref) -> i32 +!CHECK: %[[UB2_CVT:.*]] = fir.convert %[[UB2]] : (i32) -> index + +!CHECK: %[[LB3:.*]] = arith.constant 5 : i32 +!CHECK: %[[LB3_CVT:.*]] = fir.convert %[[LB3]] : (i32) -> index +!CHECK: %[[UB3:.*]] = arith.constant 10 : i32 +!CHECK: %[[UB3_CVT:.*]] = fir.convert %[[UB3]] : (i32) -> index + +!CHECK: fir.do_loop %{{.*}} = %[[LB1_CVT]] to %[[UB1_CVT]] step %{{.*}} unordered +!CHECK: fir.do_loop %{{.*}} = %[[LB2_CVT]] to %[[UB2_CVT]] step %{{.*}} unordered +!CHECK: fir.do_loop %{{.*}} = %[[LB3_CVT]] to %[[UB3_CVT]] step %{{.*}} unordered + + do concurrent(i=1:n, j=1:bar(n*m, n/m), k=5:10) + a(i) = n + end do +end subroutine + +!CHECK-LABEL: sub2 +subroutine sub2(n) + implicit none + integer :: n, m, i, j + integer, dimension(n) :: a +!CHECK: %[[LB1:.*]] = arith.constant 1 : i32 +!CHECK: %[[LB1_CVT:.*]] = fir.convert %[[LB1]] : (i32) -> index +!CHECK: %[[UB1:.*]] = fir.load %5#0 : !fir.ref +!CHECK: %[[UB1_CVT:.*]] = fir.convert %[[UB1]] : (i32) -> index +!CHECK: fir.do_loop %{{.*}} = %[[LB1_CVT]] to %[[UB1_CVT]] step %{{.*}} unordered +!CHECK: %[[LB2:.*]] = arith.constant 1 : i32 +!CHECK: %[[LB2_CVT:.*]] = fir.convert %[[LB2]] : (i32) -> index +!CHECK: %[[UB2:.*]] = fir.call @_QPbar(%{{.*}}, %{{.*}}) proc_attrs fastmath : (!fir.ref, !fir.ref) -> i32 +!CHECK: %[[UB2_CVT:.*]] = fir.convert %[[UB2]] : (i32) -> index +!CHECK: fir.do_loop %{{.*}} = %[[LB2_CVT]] to %[[UB2_CVT]] step %{{.*}} unordered + do concurrent(i=1:n) + do concurrent(j=1:bar(n*m, n/m)) + a(i) = n + end do + end do +end subroutine + + +!CHECK-LABEL: unstructured +subroutine unstructured(inner_step) + integer(4) :: i, j, inner_step + +!CHECK-NOT: cf.br +!CHECK-NOT: cf.cond_br +!CHECK: %[[LB1:.*]] = arith.constant 1 : i32 +!CHECK: %[[LB1_CVT:.*]] = fir.convert %c1_i32 : (i32) -> i16 +!CHECK: %[[UB1:.*]] = arith.constant 5 : i32 +!CHECK: %[[UB1_CVT:.*]] = fir.convert %c5_i32 : (i32) -> i16 +!CHECK: %[[STP1:.*]] = arith.constant 1 : i16 + +!CHECK-NOT: cf.br +!CHECK-NOT: cf.cond_br +!CHECK: %[[LB2:.*]] = arith.constant 3 : i32 +!CHECK: %[[LB2_CVT:.*]] = fir.convert %[[LB2]] : (i32) -> i16 +!CHECK: %[[UB2:.*]] = arith.constant 9 : i32 +!CHECK: %[[UB2_CVT:.*]] = fir.convert %[[UB2]] : (i32) -> i16 +!CHECK: %[[STP2:.*]] = fir.load %{{.*}}#0 : !fir.ref +!CHECK: %[[STP2_CVT:.*]] = fir.convert %[[STP2]] : (i32) -> i16 +!CHECK: fir.store %[[STP2_CVT]] to %{{.*}} : !fir.ref +!CHECK: cf.br ^[[I_LOOP_HEADER:.*]] + +!CHECK: ^[[I_LOOP_HEADER]]: +!CHECK-NEXT: %{{.*}} = fir.load %{{.*}} : !fir.ref +!CHECK-NEXT: %{{.*}} = arith.constant 0 : i16 +!CHECK-NEXT: %{{.*}} = arith.cmpi sgt, %{{.*}}, %{{.*}}: i16 +!CHECK-NEXT: cf.cond_br %{{.*}}, ^[[J_LOOP_HEADER:.*]], ^{{.*}} + +!CHECK: ^[[J_LOOP_HEADER]]: +!CHECK-NEXT: %[[RANGE:.*]] = arith.subi %[[UB2_CVT]], %[[LB2_CVT]] : i16 +!CHECK-NEXT: %{{.*}} = arith.addi %[[RANGE]], %[[STP2_CVT]] : i16 +!CHECK-NEXT: %{{.*}} = arith.divsi %{{.*}}, %[[STP2_CVT]] : i16 + do concurrent (integer(2)::i=1:5, j=3:9:inner_step, i.ne.3) + goto (7, 7) i+1 + print*, 'E:', i, j + 7 continue + enddo +end subroutine unstructured