29d857f183
Some passes in the flang pipeline are creating `fir.alloca` operation like `hlfir.concat`. When these allocas are located in a loop, the stack can quickly be used too much leading to segfaults. This behavior can be seen in https://github.com/jacobwilliams/json-fortran/blob/master/src/tests/jf_test_36.F90 This patch insert a call to LLVM stacksave/stackrestore in the body of the loop to reclaim the alloca in its scope. This PR is an alternative implementation to #95173
53 lines
1.7 KiB
C++
53 lines
1.7 KiB
C++
//===- StackReclaim.cpp -- Insert stacksave/stackrestore in region --------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "flang/Common/Fortran.h"
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#include "flang/Optimizer/Dialect/FIRDialect.h"
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#include "flang/Optimizer/Dialect/FIROps.h"
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#include "flang/Optimizer/Transforms/Passes.h"
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#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
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#include "mlir/IR/Matchers.h"
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#include "mlir/Pass/Pass.h"
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namespace fir {
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#define GEN_PASS_DEF_STACKRECLAIM
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#include "flang/Optimizer/Transforms/Passes.h.inc"
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} // namespace fir
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using namespace mlir;
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namespace {
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class StackReclaimPass : public fir::impl::StackReclaimBase<StackReclaimPass> {
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public:
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using StackReclaimBase<StackReclaimPass>::StackReclaimBase;
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void runOnOperation() override;
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};
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} // namespace
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void StackReclaimPass::runOnOperation() {
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auto *op = getOperation();
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auto *context = &getContext();
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mlir::OpBuilder builder(context);
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mlir::Type voidPtr = mlir::LLVM::LLVMPointerType::get(context);
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op->walk([&](fir::DoLoopOp loopOp) {
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mlir::Location loc = loopOp.getLoc();
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if (!loopOp.getRegion().getOps<fir::AllocaOp>().empty()) {
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builder.setInsertionPointToStart(&loopOp.getRegion().front());
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auto stackSaveOp = builder.create<LLVM::StackSaveOp>(loc, voidPtr);
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auto *terminator = loopOp.getRegion().back().getTerminator();
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builder.setInsertionPoint(terminator);
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builder.create<LLVM::StackRestoreOp>(loc, stackSaveOp);
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}
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});
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}
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