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[flang] Implement lowering for the PAUSE statement (Fixes #166821) (#167115)

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Implements lowering for the Fortran `PAUSE` statement.

- Handles PAUSE with no operand.
- Handles PAUSE with integer argument.
- Handles PAUSE with character literal argument.
- Adds a new lowering test: flang/test/Lower/pause-statement.f90.

Unlike STOP, PAUSE does not unconditionally terminate control flow.
The lowering preserves labels and GOTOs, consistent with legacy Fortran
behavior.

Fixes: #166821

---------

Co-authored-by: aditya nath <adityanath5002@gmail.com>
Co-authored-by: Eugene Epshteyn <eepshteyn@nvidia.com>
This commit is contained in:
sathvikreddy853
2025-11-30 08:37:14 +05:30
committed by GitHub
parent 3de11e9251
commit 70970d0a5b
2 changed files with 73 additions and 6 deletions
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51
flang/lib/Lower/Runtime.cpp
View File

@@ -169,12 +169,55 @@ void Fortran::lower::genUnlockStatement(
void Fortran::lower::genPauseStatement(
Fortran::lower::AbstractConverter &converter,
const Fortran::parser::PauseStmt &) {
const Fortran::parser::PauseStmt &stmt) {
fir::FirOpBuilder &builder = converter.getFirOpBuilder();
mlir::Location loc = converter.getCurrentLocation();
mlir::func::FuncOp callee =
fir::runtime::getRuntimeFunc<mkRTKey(PauseStatement)>(loc, builder);
fir::CallOp::create(builder, loc, callee, mlir::ValueRange{});
Fortran::lower::StatementContext stmtCtx;
llvm::SmallVector<mlir::Value> operands;
mlir::func::FuncOp callee;
mlir::FunctionType calleeType;
if (stmt.v.has_value()) {
const auto &code = stmt.v.value();
auto expr =
converter.genExprValue(*Fortran::semantics::GetExpr(code), stmtCtx);
expr.match(
// Character-valued expression -> call PauseStatementText (CHAR, LEN)
[&](const fir::CharBoxValue &x) {
callee = fir::runtime::getRuntimeFunc<mkRTKey(PauseStatementText)>(
loc, builder);
calleeType = callee.getFunctionType();
operands.push_back(
builder.createConvert(loc, calleeType.getInput(0), x.getAddr()));
operands.push_back(
builder.createConvert(loc, calleeType.getInput(1), x.getLen()));
},
// Unboxed value -> call PauseStatementInt which accepts an integer.
[&](fir::UnboxedValue x) {
callee = fir::runtime::getRuntimeFunc<mkRTKey(PauseStatementInt)>(
loc, builder);
calleeType = callee.getFunctionType();
assert(calleeType.getNumInputs() >= 1);
mlir::Value cast =
builder.createConvert(loc, calleeType.getInput(0), x);
operands.push_back(cast);
},
[&](auto) {
fir::emitFatalError(loc, "unhandled expression in PAUSE");
});
} else {
callee =
fir::runtime::getRuntimeFunc<mkRTKey(PauseStatement)>(loc, builder);
calleeType = callee.getFunctionType();
}
fir::CallOp::create(builder, loc, callee, operands);
// NOTE: PAUSE does not terminate the current block. The program may resume
// and continue normal execution, so we do not emit control-flow terminators.
}
void Fortran::lower::genPointerAssociate(fir::FirOpBuilder &builder,

28
flang/test/Lower/pause-statement.f90
View File

@@ -2,7 +2,31 @@
! CHECK-LABEL: pause_test
subroutine pause_test()
! CHECK: fir.call @_Fortran{{.*}}PauseStatement()
! CHECK-NEXT: return
pause
! CHECK: fir.call @_FortranA{{.*}}PauseStatement()
! CHECK-NEXT: return
end subroutine
! CHECK-LABEL: pause_code
subroutine pause_code()
pause 42
! CHECK: %[[c42:.*]] = arith.constant 42 : i32
! CHECK: fir.call @_FortranA{{.*}}PauseStatementInt(%[[c42]])
! CHECK-NEXT: return
end subroutine
! CHECK-LABEL: pause_msg
subroutine pause_msg()
pause "hello"
! CHECK-DAG: %[[five:.*]] = arith.constant 5 : index
! CHECK-DAG: %[[addr:.*]] = fir.address_of(@_QQ{{.*}}) : !fir.ref<!fir.char<1,5>>
! CHECK-DAG: %[[str:.*]]:2 = hlfir.declare %[[addr]] typeparams %[[five]] {fortran_attrs = #fir.var_attrs<parameter>, uniq_name = "_QQ{{.*}}"} : (!fir.ref<!fir.char<1,5>>, index) -> (!fir.ref<!fir.char<1,5>>, !fir.ref<!fir.char<1,5>>)
! CHECK-DAG: %[[buff:.*]] = fir.convert %[[str]]#0 : (!fir.ref<!fir.char<1,5>>) -> !fir.ref<i8>
! CHECK-DAG: %[[len:.*]] = fir.convert %[[five]] : (index) -> i64
! CHECK: fir.call @_FortranA{{.*}}PauseStatementText(%[[buff]], %[[len]])
! CHECK-NEXT: return
end subroutine
! CHECK-DAG: func private @_FortranA{{.*}}PauseStatement
! CHECK-DAG: func private @_FortranA{{.*}}PauseStatementInt
! CHECK-DAG: func private @_FortranA{{.*}}PauseStatementText