[CIR] Upstream var arg copy builtin (#169415)

This PR upstreams `__builtin_va_copy`, and extends the existing tests.

Author: HendrikHuebner

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -4820,6 +4820,37 @@ def CIR_VAEndOp : CIR_Op<"va_end"> {
   }];
 }
 
+def CIR_VACopyOp : CIR_Op<"va_copy"> {
+  let summary = "Copied a variable argument list";
+  let description = [{
+    The `cir.copy` operation models the C/C++ va_copy macro.
+    The variable argument list passed as the `$src_list` is copied to an
+    unitialized `va_list` in the destination operand. The next argument that
+    can be extracted from the copied list is the same as the next argument in
+    the source list. The copied list must be destroyed with `va_end`.
+
+    Example:
+
+    ```mlir
+    // %args : !cir.ptr<!cir.array<!rec___va_list_tag x 1>>
+    %p = cir.cast array_to_ptrdecay %args
+          : !cir.ptr<!cir.array<!rec___va_list_tag x 1>>
+          -> !cir.ptr<!rec___va_list_tag>
+    cir.va_copy %p to %dst
+          : (!cir.ptr<!rec___va_list_tag>, !cir.ptr<!rec___va_list_tag>)
+    ```
+  }];
+
+  let arguments = (ins
+    CIR_PointerType:$dst_list,
+    CIR_PointerType:$src_list
+  );
+
+  let assemblyFormat = [{
+    $src_list `to` $dst_list attr-dict `:` type(operands)
+  }];
+}
+
 def CIR_VAArgOp : CIR_Op<"va_arg"> {
   let summary = "Fetches next variadic element as a given type";
   let description = [{

clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp

@@ -266,7 +266,12 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID,
   case Builtin::BI__builtin_va_end:
     emitVAEnd(emitVAListRef(e->getArg(0)).getPointer());
     return {};
-
+  case Builtin::BI__builtin_va_copy: {
+    mlir::Value dstPtr = emitVAListRef(e->getArg(0)).getPointer();
+    mlir::Value srcPtr = emitVAListRef(e->getArg(1)).getPointer();
+    cir::VACopyOp::create(builder, dstPtr.getLoc(), dstPtr, srcPtr);
+    return {};
+  }
   case Builtin::BIcos:
   case Builtin::BIcosf:
   case Builtin::BIcosl:

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -4061,6 +4061,18 @@ mlir::LogicalResult CIRToLLVMVAEndOpLowering::matchAndRewrite(
   return mlir::success();
 }
 
+mlir::LogicalResult CIRToLLVMVACopyOpLowering::matchAndRewrite(
+    cir::VACopyOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  auto opaquePtr = mlir::LLVM::LLVMPointerType::get(getContext());
+  auto dstList = mlir::LLVM::BitcastOp::create(rewriter, op.getLoc(), opaquePtr,
+                                               adaptor.getDstList());
+  auto srcList = mlir::LLVM::BitcastOp::create(rewriter, op.getLoc(), opaquePtr,
+                                               adaptor.getSrcList());
+  rewriter.replaceOpWithNewOp<mlir::LLVM::VaCopyOp>(op, dstList, srcList);
+  return mlir::success();
+}
+
 mlir::LogicalResult CIRToLLVMVAArgOpLowering::matchAndRewrite(
     cir::VAArgOp op, OpAdaptor adaptor,
     mlir::ConversionPatternRewriter &rewriter) const {

clang/test/CIR/CodeGen/var_arg.c

@@ -141,7 +141,7 @@ int stdarg_start(int count, ...) {
 // OGCG:   %[[COND:.+]] = icmp ule i32 %[[GPOFFSET]], 40
 // OGCG:   br i1 %[[COND]], label %vaarg.in_reg, label %vaarg.in_mem
 //
-// OGCG: vaarg.in_reg:                                   
+// OGCG: vaarg.in_reg:
 // OGCG:   %[[REGSAVE_PTR:.+]] = getelementptr inbounds nuw %struct.__va_list_tag, ptr %[[DECAY1]], i32 0, i32 3
 // OGCG:   %[[REGSAVE:.+]] = load ptr, ptr %[[REGSAVE_PTR]]
 // OGCG:   %[[VAADDR1:.+]] = getelementptr i8, ptr %[[REGSAVE]], i32 %[[GPOFFSET]]
@@ -164,3 +164,23 @@ int stdarg_start(int count, ...) {
 // OGCG:   call void @llvm.va_end.p0(ptr %[[DECAY2]])
 // OGCG:   %[[VAL:.+]] = load i32, ptr %[[RES_ADDR]]
 // OGCG:   ret i32 %[[VAL]]
+
+void stdarg_copy() {
+    __builtin_va_list src, dest;
+    __builtin_va_copy(src, dest);
+}
+
+// CIR-LABEL: @stdarg_copy
+// CIR:    %{{.*}} = cir.cast array_to_ptrdecay %{{.*}} : !cir.ptr<!cir.array<!rec___va_list_tag x 1>> -> !cir.ptr<!rec___va_list_tag>
+// CIR:    %{{.*}} = cir.cast array_to_ptrdecay %{{.*}} : !cir.ptr<!cir.array<!rec___va_list_tag x 1>> -> !cir.ptr<!rec___va_list_tag>
+// CIR:    cir.va_copy %{{.*}} to %{{.*}} : !cir.ptr<!rec___va_list_tag>, !cir.ptr<!rec___va_list_tag>
+
+// LLVM-LABEL: @stdarg_copy
+// LLVM:   %{{.*}} = getelementptr %struct.__va_list_tag, ptr %{{.*}}
+// LLVM:   %{{.*}} = getelementptr %struct.__va_list_tag, ptr %{{.*}}
+// LLVM:   call void @llvm.va_copy.p0(ptr %{{.*}}, ptr %{{.*}}
+
+// OGCG-LABEL: @stdarg_copy
+// OGCG:   %{{.*}} = getelementptr inbounds [1 x %struct.__va_list_tag], ptr %{{.*}}
+// OGCG:   %{{.*}} = getelementptr inbounds [1 x %struct.__va_list_tag], ptr %{{.*}}
+// OGCG:   call void @llvm.va_copy.p0(ptr %{{.*}}, ptr %{{.*}}