[flang-commits] [flang] [flang][OpenMP] Add lowering for assume and assumes directives (PR #205615)
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Wed Jun 24 10:53:00 PDT 2026
https://github.com/Ritanya-B-Bharadwaj created https://github.com/llvm/llvm-project/pull/205615
Adds lowering for the assume and assumes directives. holds clauses are lowered to llvm.assume, the other assumption clauses are ignored, and assumes is a no-op. Hints are skipped under -fopenmp-simd.
>From f63249c16cf413ff9099f86107c2733a6a8bc77a Mon Sep 17 00:00:00 2001
From: Ritanya B Bharadwaj <ritanya.b.bharadwaj at gmail.com>
Date: Wed, 24 Jun 2026 12:45:59 -0500
Subject: [PATCH] Adding lowering support for assume and assumes
---
flang/lib/Lower/OpenMP/OpenMP.cpp | 33 +++++++++++++++---
flang/test/Lower/OpenMP/Todo/assume.f90 | 10 ------
flang/test/Lower/OpenMP/Todo/assumes.f90 | 6 ----
flang/test/Lower/OpenMP/assumption.f90 | 44 ++++++++++++++++++++++++
4 files changed, 72 insertions(+), 21 deletions(-)
delete mode 100644 flang/test/Lower/OpenMP/Todo/assume.f90
delete mode 100644 flang/test/Lower/OpenMP/Todo/assumes.f90
create mode 100644 flang/test/Lower/OpenMP/assumption.f90
diff --git a/flang/lib/Lower/OpenMP/OpenMP.cpp b/flang/lib/Lower/OpenMP/OpenMP.cpp
index facca9867e4bb..5f84b76cf89e2 100644
--- a/flang/lib/Lower/OpenMP/OpenMP.cpp
+++ b/flang/lib/Lower/OpenMP/OpenMP.cpp
@@ -49,6 +49,7 @@
#include "flang/Support/OpenMP-utils.h"
#include "flang/Utils/OpenMP.h"
#include "mlir/Dialect/ControlFlow/IR/ControlFlowOps.h"
+#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/OpenMP/OpenMPDialect.h"
#include "mlir/Support/StateStack.h"
#include "mlir/Transforms/RegionUtils.h"
@@ -4205,8 +4206,8 @@ static void genOMP(lower::AbstractConverter &converter, lower::SymMap &symTable,
semantics::SemanticsContext &semaCtx,
lower::pft::Evaluation &eval,
const parser::OmpAssumesDirective &assumesConstruct) {
- if (!semaCtx.langOptions().OpenMPSimd)
- TODO(converter.getCurrentLocation(), "OpenMP ASSUMES declaration");
+ // Assumption clauses are hints with no representation in the OpenMP dialect,
+ // so this declarative directive is a no-op.
}
static void
@@ -5314,9 +5315,31 @@ static void genOMP(lower::AbstractConverter &converter, lower::SymMap &symTable,
semantics::SemanticsContext &semaCtx,
lower::pft::Evaluation &eval,
const parser::OmpAssumeDirective &assumeConstruct) {
- mlir::Location clauseLocation = converter.genLocation(assumeConstruct.source);
- if (!semaCtx.langOptions().OpenMPSimd)
- TODO(clauseLocation, "OpenMP ASSUME construct");
+ if (!semaCtx.langOptions().OpenMPSimd) {
+ fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
+ lower::StatementContext stmtCtx;
+
+ const parser::OmpDirectiveSpecification &beginSpec =
+ assumeConstruct.BeginDir();
+ for (const parser::OmpClause &clause : beginSpec.Clauses().v) {
+ const auto *holds = std::get_if<parser::OmpClause::Holds>(&clause.u);
+ if (!holds)
+ continue;
+
+ mlir::Location clauseLoc = converter.genLocation(clause.source);
+ const parser::Expr &parserExpr = holds->v.v.value();
+ const semantics::SomeExpr *expr = semantics::GetExpr(semaCtx, parserExpr);
+ assert(expr && "Expecting analyzed expression for holds clause");
+
+ mlir::Value cond =
+ fir::getBase(converter.genExprValue(*expr, stmtCtx, &clauseLoc));
+ cond =
+ firOpBuilder.createConvert(clauseLoc, firOpBuilder.getI1Type(), cond);
+ mlir::LLVM::AssumeOp::create(firOpBuilder, clauseLoc, cond);
+ }
+ stmtCtx.finalizeAndPop();
+ }
+ genNestedEvaluations(converter, eval);
}
static void genOMP(lower::AbstractConverter &converter, lower::SymMap &symTable,
diff --git a/flang/test/Lower/OpenMP/Todo/assume.f90 b/flang/test/Lower/OpenMP/Todo/assume.f90
deleted file mode 100644
index 1216888efabd1..0000000000000
--- a/flang/test/Lower/OpenMP/Todo/assume.f90
+++ /dev/null
@@ -1,10 +0,0 @@
-! RUN: %not_todo_cmd %flang_fc1 -emit-fir -fopenmp -fopenmp-version=51 -o - %s 2>&1 | FileCheck %s
-
-! CHECK: not yet implemented: OpenMP ASSUME construct
-program p
- integer r
- r = 1
-!$omp assume no_parallelism
- print *,r
-!$omp end assume
-end program p
diff --git a/flang/test/Lower/OpenMP/Todo/assumes.f90 b/flang/test/Lower/OpenMP/Todo/assumes.f90
deleted file mode 100644
index ac26ed14ded3c..0000000000000
--- a/flang/test/Lower/OpenMP/Todo/assumes.f90
+++ /dev/null
@@ -1,6 +0,0 @@
-! RUN: %not_todo_cmd %flang_fc1 -emit-fir -fopenmp -fopenmp-version=51 -o - %s 2>&1 | FileCheck %s
-
-! CHECK: not yet implemented: OpenMP ASSUMES declaration
-program p
- !$omp assumes no_openmp
-end program p
diff --git a/flang/test/Lower/OpenMP/assumption.f90 b/flang/test/Lower/OpenMP/assumption.f90
new file mode 100644
index 0000000000000..65e6aa47881c9
--- /dev/null
+++ b/flang/test/Lower/OpenMP/assumption.f90
@@ -0,0 +1,44 @@
+! RUN: %flang_fc1 -emit-hlfir -fopenmp -fopenmp-version=51 -o - %s 2>&1 | FileCheck %s
+
+! Lowering of the OpenMP ASSUME construct and ASSUMES directive. Most assumption
+! clauses are optimization hints with no representation in the OpenMP dialect, so
+! the ASSUME construct lowers its associated structured block and the ASSUMES
+! directive lowers as a no-op. The HOLDS clause asserts a scalar logical
+! expression, which is lowered to an `llvm.intr.assume` intrinsic.
+
+! CHECK-LABEL: func.func @_QPassumes_decl
+subroutine assumes_decl(x)
+ !$omp assumes no_openmp
+ integer :: x
+ ! CHECK: %[[DECL:.*]]:2 = hlfir.declare
+ ! CHECK: %[[C0:.*]] = arith.constant 0 : i32
+ ! CHECK: hlfir.assign %[[C0]] to %[[DECL]]#0
+ x = 0
+end subroutine assumes_decl
+
+! CHECK-LABEL: func.func @_QPassume_construct
+subroutine assume_construct(x)
+ integer :: x
+ ! CHECK: %[[DECL:.*]]:2 = hlfir.declare
+ !$omp assume no_openmp
+ ! CHECK: %[[C1:.*]] = arith.constant 1 : i32
+ ! CHECK: hlfir.assign %[[C1]] to %[[DECL]]#0
+ x = 1
+ !$omp end assume
+end subroutine assume_construct
+
+! CHECK-LABEL: func.func @_QPassume_block
+subroutine assume_block(x)
+ integer :: x
+ ! CHECK: %[[DECL:.*]]:2 = hlfir.declare
+ !$omp assume holds(x > 0)
+ block
+ ! CHECK: %[[LOAD:.*]] = fir.load %[[DECL]]#0
+ ! CHECK: %[[C0:.*]] = arith.constant 0 : i32
+ ! CHECK: %[[CMP:.*]] = arith.cmpi sgt, %[[LOAD]], %[[C0]] : i32
+ ! CHECK: llvm.intr.assume %[[CMP]] : i1
+ ! CHECK: %[[C2:.*]] = arith.constant 2 : i32
+ ! CHECK: hlfir.assign %[[C2]] to %[[DECL]]#0
+ x = 2
+ end block
+end subroutine assume_block
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