[flang-commits] [flang] [flang] OPTIONAL char dummy has no defining op; add null check (PR #182582)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-fir-hlfir

Author: tedj (tmjbios)

<details>
<summary>Changes</summary>

size.getDefiningOp() returns nullptr for block arguments when a OPTIONAL character length generated the conditional "fir.if". Check for a nullptr before calling mlir::isa<> to avoid the crash.

Addresses: https://github.com/llvm/llvm-project/issues/182436
Passes check-flang, check-flang-rt, and llvm-test-suite (x86_64)

---
Full diff: https://github.com/llvm/llvm-project/pull/182582.diff


1 Files Affected:

- (modified) flang/lib/Optimizer/CodeGen/CodeGen.cpp (+4-1) 


``````````diff
diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
index 93f3806b18648..dc4f11d8ada8c 100644
--- a/flang/lib/Optimizer/CodeGen/CodeGen.cpp
+++ b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -319,7 +319,10 @@ struct AllocaOpConversion : public fir::FIROpConversion<fir::AllocaOp> {
     unsigned allocaAs = getAllocaAddressSpace(rewriter);
     unsigned programAs = getProgramAddressSpace(rewriter);
 
-    if (mlir::isa<mlir::LLVM::ConstantOp>(size.getDefiningOp())) {
+    // A value defined by a block arg, such as fir.if for a
+    // optional assumed character dummy len, doesn't have a defining op.
+    if (auto *defOp = size.getDefiningOp();
+        defOp && mlir::isa<mlir::LLVM::ConstantOp>(size.getDefiningOp())) {
       // Set the Block in which the llvm alloca should be inserted.
       mlir::Operation *parentOp = rewriter.getInsertionBlock()->getParentOp();
       mlir::Region *parentRegion = rewriter.getInsertionBlock()->getParent();

``````````

</details>


https://github.com/llvm/llvm-project/pull/182582