gen/abi: add initial ABI implementations for s390x

Author: liushuyu

gen/abi/abi.cpp

@@ -281,6 +281,8 @@ TargetABI *TargetABI::getTarget() {
   case llvm::Triple::wasm32:
   case llvm::Triple::wasm64:
     return getWasmTargetABI();
+  case llvm::Triple::systemz:
+    return getSystemZTargetABI();
   default:
     warning(Loc(),
             "unknown target ABI, falling back to generic implementation. C/C++ "

gen/abi/systemz.cpp

@@ -0,0 +1,69 @@
+//===-- abi-systemz.cpp
+//-----------------------------------------------------===//
+//
+//                         LDC - the LLVM D compiler
+//
+// This file is distributed under the BSD-style LDC license. See the LICENSE
+// file for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The ABI implementation used for 64 bit big-endian IBM Z targets.
+//
+// The IBM s390x ELF ABI can be found here:
+// https://github.com/IBM/s390x-abi
+//===----------------------------------------------------------------------===//
+
+#include "gen/abi/abi.h"
+#include "gen/abi/generic.h"
+#include "gen/dvalue.h"
+#include "gen/irstate.h"
+#include "gen/llvmhelpers.h"
+#include "gen/tollvm.h"
+
+struct SystemZTargetABI : TargetABI {
+  IndirectByvalRewrite indirectByvalRewrite{};
+
+  explicit SystemZTargetABI() {}
+
+  bool returnInArg(TypeFunction *tf, bool) override {
+    if (tf->isref()) {
+      return false;
+    }
+    Type *rt = tf->next->toBasetype();
+    return DtoIsInMemoryOnly(rt);
+  }
+
+  bool passByVal(TypeFunction *, Type *t) override {
+    return DtoIsInMemoryOnly(t);
+  }
+
+  void rewriteFunctionType(IrFuncTy &fty) override {
+    if (!fty.ret->byref) {
+      rewriteArgument(fty, *fty.ret);
+    }
+
+    for (auto arg : fty.args) {
+      if (!arg->byref) {
+        rewriteArgument(fty, *arg);
+      }
+    }
+  }
+
+  void rewriteArgument(IrFuncTy &fty, IrFuncTyArg &arg) override {
+    if (!isPOD(arg.type)) {
+      // non-PODs should be passed in memory
+      indirectByvalRewrite.applyTo(arg);
+      return;
+    }
+    Type *ty = arg.type->toBasetype();
+    // integer types less than 64-bits should be extended to 64 bits
+    if (ty->isintegral()) {
+      arg.attrs.addAttribute(ty->isunsigned() ? LLAttribute::ZExt
+                                              : LLAttribute::SExt);
+    }
+  }
+};
+
+// The public getter for abi.cpp
+TargetABI *getSystemZTargetABI() { return new SystemZTargetABI(); }

gen/abi/targets.h

@@ -40,3 +40,5 @@ TargetABI *getX86TargetABI();
 TargetABI *getLoongArch64TargetABI();
 
 TargetABI *getWasmTargetABI();
+
+TargetABI *getSystemZTargetABI();