[llvm] [mlir] [MLIR][OpenMP] Add Taskloop Collapse Support (PR #175924)

[Tom Eccles via llvm-commits]

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@@ -2797,6 +2789,22 @@ convertOmpTaskloopOp(Operation &opInst, llvm::IRBuilderBase &builder,
     return loopInfo;
   };
 
+  llvm::Value *ubVal = builder.getInt32(1);
+  Operation::operand_range lowerBounds = loopOp.getLoopLowerBounds();
+  Operation::operand_range upperBounds = loopOp.getLoopUpperBounds();
+  if (loopOp.getCollapseNumLoops() > 1) {
+    for (uint64_t i = 0; i < loopOp.getCollapseNumLoops(); i++) {
+      ubVal = builder.CreateMul(
+          ubVal,
+          builder.CreateSub(
+              moduleTranslation.lookupValue(upperBounds[i]),
+              builder.CreateSub(moduleTranslation.lookupValue(lowerBounds[i]),
+                                builder.getInt32(1))));
+    }
+  } else {
+    ubVal = moduleTranslation.lookupValue(upperBounds[0]);
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tblah wrote:

So this is related to the differences in lower bound handling inside of OMPIRBuilder that you offered to try cleaning up in a subsequent commit?

https://github.com/llvm/llvm-project/pull/175924