[flang-commits] [flang] [flang] Insert stacksave/stackrestore when alloca are present in loops (PR #95173)

[Valentin Clement バレンタイン クレメン via flang-commits]

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@@ -72,6 +75,22 @@ class CfgLoopConv : public mlir::OpRewritePattern<fir::DoLoopOp> {
         rewriter.splitBlock(conditionalBlock, conditionalBlock->begin());
     auto *lastBlock = &loop.getRegion().back();
 
+    // Insert stacksave/stackrestore if there is fir.alloca operation in the
+    // loop.
+    if (hasAllocas) {
+      auto mod = loop.getOperation()->getParentOfType<mlir::ModuleOp>();
+      fir::FirOpBuilder builder(rewriter, mod);
+      builder.setInsertionPointToStart(firstBlock);
+      mlir::func::FuncOp stackSave = fir::factory::getLlvmStackSave(builder);
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clementval wrote:

> This seems to require making the pass a module pass. This is quite unfortunate.
Yeah if we can avoid that it would probably be better. 

> Would that be possible to insert stacksave/stackrestore calls during hlfir.concat bufferization? It might be inefficient, but we will get correct code at least. The redundant stacksave/stackrestore might be optimized after that.

Yes we can be then we would miss other case (if any) of fir.alloca with dynamic size in loops. 

https://github.com/llvm/llvm-project/pull/95173