[clang] [Clang][CodeGen] Use EmitLoadOfLValue instead of EmitLoadOfScalar to get LHS for complex compound assignment (PR #166798)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Benjamin Stott (BStott6)

<details>
<summary>Changes</summary>

- Fixes https://github.com/llvm/llvm-project/issues/166512
- `ComplexExprEmitter::EmitCompoundAssignLValue` is calling `EmitLoadOfScalar(LValue, SourceLocation)` to load the LHS value in the case that it's non-complex, however this function requires that the value is a simple LValue - issue occurred because the LValue in question was a bitfield LValue. I changed it to use this function which seems to handle all of the different cases (deferring to the original `EmitLoadOfScalar` if it's a simple LValue)

Note that I am new to Clang and I'm not confident this is the right change; it makes sense to me, fixes the crash and passes all tests but please check carefully!

---
Full diff: https://github.com/llvm/llvm-project/pull/166798.diff


1 Files Affected:

- (modified) clang/lib/CodeGen/CGExprComplex.cpp (+1-1) 


``````````diff
diff --git a/clang/lib/CodeGen/CGExprComplex.cpp b/clang/lib/CodeGen/CGExprComplex.cpp
index f8a946a76554a..47435758fcde7 100644
--- a/clang/lib/CodeGen/CGExprComplex.cpp
+++ b/clang/lib/CodeGen/CGExprComplex.cpp
@@ -1283,7 +1283,7 @@ EmitCompoundAssignLValue(const CompoundAssignOperator *E,
     else
       OpInfo.LHS = EmitComplexToComplexCast(LHSVal, LHSTy, OpInfo.Ty, Loc);
   } else {
-    llvm::Value *LHSVal = CGF.EmitLoadOfScalar(LHS, Loc);
+    llvm::Value *LHSVal = CGF.EmitLoadOfLValue(LHS, Loc).getScalarVal();
     // For floating point real operands we can directly pass the scalar form
     // to the binary operator emission and potentially get more efficient code.
     if (LHSTy->isRealFloatingType()) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/166798