Auto merge of #86873 - nikic:opaque-ptrs, r=nagisa

Improve opaque pointers support

Opaque pointers are coming, and rustc is not ready.

This adds partial support by passing an explicit load type to LLVM. Two issues I've encountered:
 * The necessary type was not available at the point where non-temporal copies were generated. I've pushed the code for that upwards out of the memcpy implementation and moved the position of a cast to make do with the types we have available. (I'm not sure that cast is needed at all, but have retained it in the interest of conservativeness.)
 * The `PlaceRef::project_deref()` function used during debuginfo generation seems to be buggy in some way -- though I haven't figured out specifically what it does wrong. Replacing it with `load_operand().deref()` did the trick, but I don't really know what I'm doing here.

1 files changed, 3 insertions, 4 deletions

diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index 9b757eb40c1..4cdc8a4155b 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -349,11 +349,10 @@ extern "C" void LLVMRustSetFastMath(LLVMValueRef V) {
 }
 
 extern "C" LLVMValueRef
-LLVMRustBuildAtomicLoad(LLVMBuilderRef B, LLVMValueRef Source, const char *Name,
-                        LLVMAtomicOrdering Order) {
+LLVMRustBuildAtomicLoad(LLVMBuilderRef B, LLVMTypeRef Ty, LLVMValueRef Source,
+                        const char *Name, LLVMAtomicOrdering Order) {
   Value *Ptr = unwrap(Source);
-  Type *Ty = Ptr->getType()->getPointerElementType();
-  LoadInst *LI = unwrap(B)->CreateLoad(Ty, Ptr, Name);
+  LoadInst *LI = unwrap(B)->CreateLoad(unwrap(Ty), Ptr, Name);
   LI->setAtomic(fromRust(Order));
   return wrap(LI);
 }