[llvm] Fixed AddressSpaceCast in CodeExtractor (PR #96230)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Eric Wright (efwright)

<details>
<summary>Changes</summary>

In the CodeExtractor if aggregate arguments are used it allocates a struct to hold variables needed to be passed into an outlined function. Then, if this alloca was not in the default address space an AddressSpaceCast was emitted. However, this new instruction was unused, and the code instead just continued to reference the original alloca instruction.

This PR changes it so that the AddressSpaceCast is actually used instead of the original alloca.

---
Full diff: https://github.com/llvm/llvm-project/pull/96230.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/Utils/CodeExtractor.cpp (+7-6) 


``````````diff
diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
index b2775eb6c6c7a..2d4d8e62bf3c5 100644
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -1195,7 +1195,7 @@ CallInst *CodeExtractor::emitCallAndSwitchStatement(Function *newFunction,
   }
 
   StructType *StructArgTy = nullptr;
-  AllocaInst *Struct = nullptr;
+  Instruction *Struct = nullptr;
   unsigned NumAggregatedInputs = 0;
   if (AggregateArgs && !StructValues.empty()) {
     std::vector<Type *> ArgTypes;
@@ -1204,19 +1204,20 @@ CallInst *CodeExtractor::emitCallAndSwitchStatement(Function *newFunction,
 
     // Allocate a struct at the beginning of this function
     StructArgTy = StructType::get(newFunction->getContext(), ArgTypes);
-    Struct = new AllocaInst(
+    auto *StructAlloca = new AllocaInst(
         StructArgTy, DL.getAllocaAddrSpace(), nullptr, "structArg",
         AllocationBlock ? AllocationBlock->getFirstInsertionPt()
                         : codeReplacer->getParent()->front().begin());
 
     if (ArgsInZeroAddressSpace && DL.getAllocaAddrSpace() != 0) {
       auto *StructSpaceCast = new AddrSpaceCastInst(
-          Struct, PointerType ::get(Context, 0), "structArg.ascast");
-      StructSpaceCast->insertAfter(Struct);
-      params.push_back(StructSpaceCast);
+          StructAlloca, PointerType ::get(Context, 0), "structArg.ascast");
+      StructSpaceCast->insertAfter(StructAlloca);
+      Struct = StructSpaceCast;
     } else {
-      params.push_back(Struct);
+      Struct = StructAlloca;
     }
+    params.push_back(Struct);
     // Store aggregated inputs in the struct.
     for (unsigned i = 0, e = StructValues.size(); i != e; ++i) {
       if (inputs.contains(StructValues[i])) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/96230