[Openmp-commits] [mlir] [openmp] [llvm] [OpenMP][OMPIRBuilder] Handle replace uses of ConstantExpr's inside of Target regions (PR #71891)

Sergio Afonso via Openmp-commits openmp-commits at lists.llvm.org
Fri Nov 10 04:47:49 PST 2023

@@ -4817,11 +4817,39 @@ static Function *createOutlinedFunction(
         ArgAccessorFuncCB(Arg, Input, InputCopy, AllocaIP, Builder.saveIP()));
-    // Collect all the instructions
+    // Things like GEP's can come in the form of Constants, constants and
+    // ConstantExpr's do not have access to the knowledge of what they're
+    // contained in, so we must dig a little to find an instruction so we can
+    // tell if they're used inside of the function we're outlining. We also
+    // replace the original constant expression with a new instruction
+    // equivelant; an instruction as it allows easy modification in the
+    // following loop, as we can now know the constant (instruction) is owned by
+    // our target function and replaceUsesOfWith can now be invoked on it
+    // (cannot do this with constants it seems), a brand new one also allows us
+    // to be cautious as it is perhaps possible the old expression was used
+    // inside of the function but exists and is used externally (unlikely by the
+    // nature of a Constant, but still)
+    auto ReplaceConstantUsedInFunction = [](Constant *Const, Function *Func) {
+      if (auto *ConstExpr = dyn_cast<ConstantExpr>(Const))
+        for (User *User : make_early_inc_range(ConstExpr->users()))
+          if (auto *Instr = dyn_cast<Instruction>(User))
+            if (Instr->getFunction() == Func)
+              Instr->replaceUsesOfWith(ConstExpr,
+                                       ConstExpr->getAsInstruction(Instr));
+    };
     for (User *User : make_early_inc_range(Input->users()))
-      if (auto Instr = dyn_cast<Instruction>(User))
-        if (Instr->getFunction() == Func)
+      if (auto *Const = dyn_cast<Constant>(User))
skatrak wrote:

Is there any reason why `User` can't be checked here for the `ConstantExpr` type directly and remove the check at the top of the `ReplaceConstantUsedInFunction` lambda?


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