[flang] Implement lowering for the PAUSE statement (Fixes #166821) #167115
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This patch adds lowering support for the Fortran PAUSE statement to FIR. It mirrors the STOP statement lowering logic to handle: - PAUSE with no operand - PAUSE <integer> - PAUSE 'message' Fixes llvm#166821.
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@llvm/pr-subscribers-flang-fir-hlfir Author: None (sathvikreddy853) ChangesImplements lowering for the Fortran
Unlike STOP, PAUSE does not unconditionally terminate control flow. Fixes: #166821 Full diff: https://github.com/llvm/llvm-project/pull/167115.diff 2 Files Affected:
diff --git a/flang/lib/Lower/Runtime.cpp b/flang/lib/Lower/Runtime.cpp
index cb555249125f6..48c70f4180de0 100644
--- a/flang/lib/Lower/Runtime.cpp
+++ b/flang/lib/Lower/Runtime.cpp
@@ -263,12 +263,56 @@ void Fortran::lower::genSyncTeamStatement(
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);
+ LLVM_DEBUG(llvm::dbgs() << "pause expression: "; expr.dump(); llvm::dbgs() << '\n');
+ 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()));
+ },
+ // Numeric/unboxed value -> call PauseStatement which accepts an integer code.
+ [&](fir::UnboxedValue x) {
+ callee = fir::runtime::getRuntimeFunc<mkRTKey(PauseStatement)>(loc, builder);
+ calleeType = callee.getFunctionType();
+ if (calleeType.getNumInputs() >= 1) {
+ mlir::Value cast =
+ builder.createConvert(loc, calleeType.getInput(0), x);
+ operands.push_back(cast);
+ }
+ },
+ [&](auto) {
+ mlir::emitError(loc, "unhandled expression in PAUSE");
+ std::exit(1);
+ });
+ } else {
+ callee = fir::runtime::getRuntimeFunc<mkRTKey(PauseStatement)>(loc, builder);
+ calleeType = callee.getFunctionType();
+ }
+
+ fir::CallOp::create(builder, loc, callee, operands);
+
+ // NOTE: PAUSE should not unconditionally terminate the current block.
+ // Unlike STOP, PAUSE does not necessarily abandon control flow, so do not
+ // subsequent control flow (e.g. GOTO/branches) to be generated.
+ // insert genUnreachable() here. Leaving the block un-terminated allows
}
void Fortran::lower::genPointerAssociate(fir::FirOpBuilder &builder,
diff --git a/flang/test/Lower/pause-statement.f90 b/flang/test/Lower/pause-statement.f90
index f4c8f6fbc4385..926f81e96cefd 100644
--- a/flang/test/Lower/pause-statement.f90
+++ b/flang/test/Lower/pause-statement.f90
@@ -1,4 +1,4 @@
-! RUN: bbc %s -emit-fir --canonicalize -o - | FileCheck %s
+! RUN: bbc %s -emit-fir -hlfir=false --canonicalize -o - | FileCheck %s
! CHECK-LABEL: pause_test
subroutine pause_test()
@@ -6,3 +6,24 @@ subroutine pause_test()
! CHECK-NEXT: return
pause
end subroutine
+
+! CHECK-LABEL: pause_code
+subroutine pause_code()
+ pause 42
+ ! CHECK: fir.call @_Fortran{{.*}}PauseStatement
+ ! CHECK-NEXT: return
+end subroutine
+
+! CHECK-LABEL: pause_msg
+subroutine pause_msg()
+ pause "hello"
+ ! CHECK-DAG: %[[five:.*]] = arith.constant 5 : index
+ ! CHECK-DAG: %[[lit:.*]] = fir.address_of(@_QQ{{.*}}) : !fir.ref<!fir.char<1,5>>
+ ! CHECK-DAG: %[[buff:.*]] = fir.convert %[[lit]] : (!fir.ref<!fir.char<1,5>>) -> !fir.ref<i8>
+ ! CHECK-DAG: %[[len:.*]] = fir.convert %[[five]] : (index) -> i64
+ ! CHECK: fir.call @_Fortran{{.*}}PauseStatementText(%[[buff]], %[[len]])
+ ! CHECK-NEXT: return
+end subroutine
+
+! CHECK-DAG: func private @_Fortran{{.*}}PauseStatement
+! CHECK-DAG: func private @_Fortran{{.*}}PauseStatementText
\ No newline at end of file
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jeanPerier
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Thanks for working on this.
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Hey @jeanPerier, thanks for your review. I have made the required changes could you please review it once again. |
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Thanks, few more nits, LGTM otherwise.
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Once Jean approves this PR, I want to run some internal tests before it's merged. ( @sathvikreddy853 won't be able to merge it anyway, so I'll take care of merging once I run the tests.) |
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Hey @jeanPerier and @eugeneepshteyn. I have made all the required changes. Could please take one more look at it? |
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Hi @jeanPerier, @eugeneepshteyn. Just a quick follow‑up (no rush at all). I’ve addressed the requested changes on this PAUSE lowering PR and would really appreciate another review when you have time. |
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Please remove the --hlfir=false option on the test, LGTM otherwise, thanks.
Remove hlfir and add an additional check for hlfir.declare
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Removed |
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Thank you for the review and approval! |
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Hi @eugeneepshteyn, @jeanPerier has approved this PR. When you have a moment, could you please run the internal tests and handle the merge if everything looks good? Thanks! |
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Implements lowering for the Fortran
PAUSEstatement.Unlike STOP, PAUSE does not unconditionally terminate control flow.
The lowering preserves labels and GOTOs, consistent with legacy Fortran behavior.
Fixes: #166821