[flang-commits] [flang] [flang] fix hlfir stack merging issue on AIX (PR #78435)

[via flang-commits]

https://github.com/madanial0 created https://github.com/llvm/llvm-project/pull/78435

When running the `flang/test/HLFIR/simplify-hlfir-intrinsics.fir` test case on AIX we encounter issues building op as they are not found in the mlir context:
```
LLVM ERROR: Building op `arith.subi` but it isn't known in this MLIRContext: the dialect may not be loaded or this operation hasn't been added by the dialect. See also https://mlir.llvm.org/getting_started/Faq/#registered-loaded-dependent-whats-up-with-dialects-management
LLVM ERROR: Building op `hlfir.yield_element` but it isn't known in this MLIRContext: the dialect may not be loaded or this operation hasn't been added by the dialect. See also https://mlir.llvm.org/getting_started/Faq/#registered-loaded-dependent-whats-up-with-dialects-management
LLVM ERROR: Building op `hlfir.yield_element` but it isn't known in this MLIRContext: the dialect may not be loaded or this operation hasn't been added by the dialect. See also https://mlir.llvm.org/getting_started/Faq/#registered-loaded-dependent-whats-up-with-dialects-management
```
The issue is caused by the "Merge disjoint stack slots" pass and the error is not present if the source is built with `-mllvm --no-stack-coloring`  

Thanks to investigation by @stefanp-ibm we found that "the initializer_list {inputIndices[1], inputIndices[0]} has a lifetime that only exists for the range of the constructor for ValueRange. Once we get to stack coloring we merge the stack slot for that element with another stack slot and then it gets overwritten which corrupts transposedIndices"

The changes below prevents the corruption of transposedIndices and passes the test case.

>From 1b4080ecaac67d953c4dca828d57b3dd3cf3f4fe Mon Sep 17 00:00:00 2001
From: Mark Danial <madanial at dixon.rtp.raleigh.ibm.com>
Date: Mon, 15 Jan 2024 10:58:09 -0500
Subject: [PATCH] [flang] fix hlfir stack issue on AIX

---
 .../lib/Optimizer/HLFIR/Transforms/SimplifyHLFIRIntrinsics.cpp | 3 ++-
 flang/test/HLFIR/simplify-hlfir-intrinsics.fir                 | 3 ---
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/flang/lib/Optimizer/HLFIR/Transforms/SimplifyHLFIRIntrinsics.cpp b/flang/lib/Optimizer/HLFIR/Transforms/SimplifyHLFIRIntrinsics.cpp
index 5f065056bac00c9..c15ea737366c71d 100644
--- a/flang/lib/Optimizer/HLFIR/Transforms/SimplifyHLFIRIntrinsics.cpp
+++ b/flang/lib/Optimizer/HLFIR/Transforms/SimplifyHLFIRIntrinsics.cpp
@@ -50,7 +50,8 @@ class TransposeAsElementalConversion
     auto genKernel = [&array](mlir::Location loc, fir::FirOpBuilder &builder,
                               mlir::ValueRange inputIndices) -> hlfir::Entity {
       assert(inputIndices.size() == 2 && "checked in TransposeOp::validate");
-      mlir::ValueRange transposedIndices{{inputIndices[1], inputIndices[0]}};
+      const std::initializer_list<mlir::Value> initList = {inputIndices[1], inputIndices[0]};
+      mlir::ValueRange transposedIndices(initList);
       hlfir::Entity element =
           hlfir::getElementAt(loc, builder, array, transposedIndices);
       hlfir::Entity val = hlfir::loadTrivialScalar(loc, builder, element);
diff --git a/flang/test/HLFIR/simplify-hlfir-intrinsics.fir b/flang/test/HLFIR/simplify-hlfir-intrinsics.fir
index b63ddf175152811..aeea8bfc9732662 100644
--- a/flang/test/HLFIR/simplify-hlfir-intrinsics.fir
+++ b/flang/test/HLFIR/simplify-hlfir-intrinsics.fir
@@ -1,6 +1,3 @@
-// XFail the following test case on AIX due to potential miscompilation
-// TODO: Crash fir-opt on AIX
-// XFAIL: system-aix
 // RUN: fir-opt --simplify-hlfir-intrinsics %s | FileCheck %s
 
 // box with known extents