[flang] [llvm] [mlir] [llvm][mlir][OpenMP] Support translation for linear clause in omp.wsloop (PR #139386)

[via llvm-commits]

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@@ -124,6 +124,146 @@ class PreviouslyReportedError
 
 char PreviouslyReportedError::ID = 0;
 
+/*
+ * Custom class for processing linear clause for omp.wsloop
+ * and omp.simd. Linear clause translation requires setup,
+ * initialization, update, and finalization at varying
+ * basic blocks in the IR. This class helps maintain
+ * internal state to allow consistent translation in
+ * each of these stages.
+ */
+
+class LinearClauseProcessor {
+
+private:
+  SmallVector<llvm::Value *> linearPreconditionVars;
+  SmallVector<llvm::Value *> linearLoopBodyTemps;
+  SmallVector<llvm::AllocaInst *> linearOrigVars;
+  SmallVector<llvm::Value *> linearOrigVal;
+  SmallVector<llvm::Value *> linearSteps;
+  llvm::BasicBlock *linearFinalizationBB;
+  llvm::BasicBlock *linearExitBB;
+  llvm::BasicBlock *linearLastIterExitBB;
+
+public:
+  // Allocate space for linear variabes
+  void createLinearVar(llvm::IRBuilderBase &builder,
+                       LLVM::ModuleTranslation &moduleTranslation,
+                       mlir::Value &linearVar) {
+    if (llvm::AllocaInst *linearVarAlloca = dyn_cast<llvm::AllocaInst>(
+            moduleTranslation.lookupValue(linearVar))) {
+      linearPreconditionVars.push_back(builder.CreateAlloca(
+          linearVarAlloca->getAllocatedType(), nullptr, ".linear_var"));
+      llvm::Value *linearLoopBodyTemp = builder.CreateAlloca(
+          linearVarAlloca->getAllocatedType(), nullptr, ".linear_result");
+      linearOrigVal.push_back(moduleTranslation.lookupValue(linearVar));
+      linearLoopBodyTemps.push_back(linearLoopBodyTemp);
+      linearOrigVars.push_back(linearVarAlloca);
+    }
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NimishMishra wrote:

Understood. I'll go over the privatisation/reduction patches to see how they manage such a case. I am assuming they hit an assertion failure, but will check and accordingly modify here.  

https://github.com/llvm/llvm-project/pull/139386