[AArch64] Use ptrmask for vaarg stack alignment (#92836)

Author: JonChesterfield

clang/lib/CodeGen/Targets/AArch64.cpp

@@ -750,18 +750,7 @@ Address AArch64ABIInfo::EmitAAPCSVAArg(Address VAListAddr, QualType Ty,
   // Again, stack arguments may need realignment. In this case both integer and
   // floating-point ones might be affected.
   if (!IsIndirect && TyAlign.getQuantity() > 8) {
-    int Align = TyAlign.getQuantity();
-
-    OnStackPtr = CGF.Builder.CreatePtrToInt(OnStackPtr, CGF.Int64Ty);
-
-    OnStackPtr = CGF.Builder.CreateAdd(
-        OnStackPtr, llvm::ConstantInt::get(CGF.Int64Ty, Align - 1),
-        "align_stack");
-    OnStackPtr = CGF.Builder.CreateAnd(
-        OnStackPtr, llvm::ConstantInt::get(CGF.Int64Ty, -Align),
-        "align_stack");
-
-    OnStackPtr = CGF.Builder.CreateIntToPtr(OnStackPtr, CGF.Int8PtrTy);
+    OnStackPtr = emitRoundPointerUpToAlignment(CGF, OnStackPtr, TyAlign);
   }
   Address OnStackAddr = Address(OnStackPtr, CGF.Int8Ty,
                                 std::max(CharUnits::fromQuantity(8), TyAlign));

clang/test/CodeGen/aarch64-varargs.c

@@ -63,10 +63,8 @@ __int128 aligned_int(void) {
 
 // CHECK: [[VAARG_ON_STACK]]
 // CHECK: [[STACK:%[a-z_0-9]+]] = load ptr, ptr @the_list
-// CHECK: [[STACKINT:%[a-z_0-9]+]] = ptrtoint ptr [[STACK]] to i64
-// CHECK: [[ALIGN_STACK:%[a-z_0-9]+]] = add i64 [[STACKINT]], 15
-// CHECK: [[ALIGNED_STACK_INT:%[a-z_0-9]+]] = and i64 [[ALIGN_STACK]], -16
-// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9]+]] = inttoptr i64 [[ALIGNED_STACK_INT]] to ptr
+// CHECK: [[STACKINC:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[STACK]], i32 15
+// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9.]+]] = call ptr @llvm.ptrmask.p0.i64(ptr [[STACKINC]], i64 -16)
 // CHECK: [[NEW_STACK:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[ALIGNED_STACK_PTR]], i64 16
 // CHECK: store ptr [[NEW_STACK]], ptr @the_list
 // CHECK: br label %[[VAARG_END]]
@@ -377,10 +375,8 @@ underaligned_int128 underaligned_int128_test(void) {
 
 // CHECK: [[VAARG_ON_STACK]]
 // CHECK: [[STACK:%[a-z_0-9]+]] = load ptr, ptr @the_list
-// CHECK: [[STACKINT:%[a-z_0-9]+]] = ptrtoint ptr [[STACK]] to i64
-// CHECK: [[ALIGN_STACK:%[a-z_0-9]+]] = add i64 [[STACKINT]], 15
-// CHECK: [[ALIGNED_STACK_INT:%[a-z_0-9]+]] = and i64 [[ALIGN_STACK]], -16
-// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9]+]] = inttoptr i64 [[ALIGNED_STACK_INT]] to ptr
+// CHECK: [[STACKINC:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[STACK]], i32 15
+// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9.]+]] = call ptr @llvm.ptrmask.p0.i64(ptr [[STACKINC]], i64 -16)
 // CHECK: [[NEW_STACK:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[ALIGNED_STACK_PTR]], i64 16
 // CHECK: store ptr [[NEW_STACK]], ptr @the_list
 // CHECK: br label %[[VAARG_END]]
@@ -414,10 +410,8 @@ overaligned_int128 overaligned_int128_test(void) {
 
 // CHECK: [[VAARG_ON_STACK]]
 // CHECK: [[STACK:%[a-z_0-9]+]] = load ptr, ptr @the_list
-// CHECK: [[STACKINT:%[a-z_0-9]+]] = ptrtoint ptr [[STACK]] to i64
-// CHECK: [[ALIGN_STACK:%[a-z_0-9]+]] = add i64 [[STACKINT]], 15
-// CHECK: [[ALIGNED_STACK_INT:%[a-z_0-9]+]] = and i64 [[ALIGN_STACK]], -16
-// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9]+]] = inttoptr i64 [[ALIGNED_STACK_INT]] to ptr
+// CHECK: [[STACKINC:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[STACK]], i32 15
+// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9.]+]] = call ptr @llvm.ptrmask.p0.i64(ptr [[STACKINC]], i64 -16)
 // CHECK: [[NEW_STACK:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[ALIGNED_STACK_PTR]], i64 16
 // CHECK: store ptr [[NEW_STACK]], ptr @the_list
 // CHECK: br label %[[VAARG_END]]
@@ -688,10 +682,8 @@ overaligned_int_struct_member overaligned_int_struct_member_test(void) {
 
 // CHECK: [[VAARG_ON_STACK]]
 // CHECK: [[STACK:%[a-z_0-9]+]] = load ptr, ptr @the_list
-// CHECK: [[STACKINT:%[a-z_0-9]+]] = ptrtoint ptr [[STACK]] to i64
-// CHECK: [[ALIGN_STACK:%[a-z_0-9]+]] = add i64 [[STACKINT]], 15
-// CHECK: [[ALIGNED_STACK_INT:%[a-z_0-9]+]] = and i64 [[ALIGN_STACK]], -16
-// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9]+]] = inttoptr i64 [[ALIGNED_STACK_INT]] to ptr
+// CHECK: [[STACKINC:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[STACK]], i32 15
+// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9.]+]] = call ptr @llvm.ptrmask.p0.i64(ptr [[STACKINC]], i64 -16)
 // CHECK: [[NEW_STACK:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[ALIGNED_STACK_PTR]], i64 16
 // CHECK: store ptr [[NEW_STACK]], ptr @the_list
 // CHECK: br label %[[VAARG_END]]
@@ -756,10 +748,8 @@ overaligned_long_long_struct_member overaligned_long_long_struct_member_test(voi
 
 // CHECK: [[VAARG_ON_STACK]]
 // CHECK: [[STACK:%[a-z_0-9]+]] = load ptr, ptr @the_list
-// CHECK: [[STACKINT:%[a-z_0-9]+]] = ptrtoint ptr [[STACK]] to i64
-// CHECK: [[ALIGN_STACK:%[a-z_0-9]+]] = add i64 [[STACKINT]], 15
-// CHECK: [[ALIGNED_STACK_INT:%[a-z_0-9]+]] = and i64 [[ALIGN_STACK]], -16
-// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9]+]] = inttoptr i64 [[ALIGNED_STACK_INT]] to ptr
+// CHECK: [[STACKINC:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[STACK]], i32 15
+// CHECK: [[ALIGNED_STACK_PTR:%[a-z_0-9.]+]] = call ptr @llvm.ptrmask.p0.i64(ptr [[STACKINC]], i64 -16)
 // CHECK: [[NEW_STACK:%[a-z_0-9]+]] = getelementptr inbounds i8, ptr [[ALIGNED_STACK_PTR]], i64 16
 // CHECK: store ptr [[NEW_STACK]], ptr @the_list
 // CHECK: br label %[[VAARG_END]]