clang/test/OpenMP/target_teams_distribute_depend_codegen.cpp

   1 // Test host codegen.
   2 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefix CHECK --check-prefix CHECK-64
   3 // RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-pch -o %t %s
   4 // RUN: %clang_cc1 -fopenmp -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -std=c++11 -include-pch %t -verify -Wno-vla %s -emit-llvm -o - | FileCheck %s --check-prefix CHECK --check-prefix CHECK-64
   5 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefix CHECK --check-prefix CHECK-32
   6 // RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-pch -o %t %s
   7 // RUN: %clang_cc1 -fopenmp -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -std=c++11 -include-pch %t -verify -Wno-vla %s -emit-llvm -o - | FileCheck %s --check-prefix CHECK --check-prefix CHECK-32
   8
   9 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp-simd -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-llvm %s -o - | FileCheck --check-prefix SIMD-ONLY0 %s
  10 // RUN: %clang_cc1 -fopenmp-simd -x c++ -std=c++11 -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-pch -o %t %s
  11 // RUN: %clang_cc1 -fopenmp-simd -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -std=c++11 -include-pch %t -verify -Wno-vla %s -emit-llvm -o - | FileCheck --check-prefix SIMD-ONLY0 %s
  12 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp-simd -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-llvm %s -o - | FileCheck --check-prefix SIMD-ONLY0 %s
  13 // RUN: %clang_cc1 -fopenmp-simd -x c++ -std=c++11 -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-pch -o %t %s
  14 // RUN: %clang_cc1 -fopenmp-simd -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -std=c++11 -include-pch %t -verify -Wno-vla %s -emit-llvm -o - | FileCheck --check-prefix SIMD-ONLY0 %s
  15 // SIMD-ONLY0-NOT: {{__kmpc|__tgt}}
  16
  17 // Test target codegen - host bc file has to be created first.
  18 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-llvm-bc %s -o %t-ppc-host.bc
  19 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-llvm %s -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-ppc-host.bc -o - | FileCheck %s --check-prefix TCHECK --check-prefix TCHECK-64
  20 // RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-pch -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-ppc-host.bc -o %t %s
  21 // RUN: %clang_cc1 -fopenmp -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -std=c++11 -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-ppc-host.bc -include-pch %t -verify -Wno-vla %s -emit-llvm -o - | FileCheck %s --check-prefix TCHECK --check-prefix TCHECK-64
  22 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-llvm-bc %s -o %t-x86-host.bc
  23 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-llvm %s -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-x86-host.bc -o - | FileCheck %s --check-prefix TCHECK --check-prefix TCHECK-32
  24 // RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-pch -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-x86-host.bc -o %t %s
  25 // RUN: %clang_cc1 -fopenmp -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -std=c++11 -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-x86-host.bc -include-pch %t -verify -Wno-vla %s -emit-llvm -o - | FileCheck %s --check-prefix TCHECK --check-prefix TCHECK-32
  26
  27 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp-simd -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-llvm-bc %s -o %t-ppc-host.bc
  28 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp-simd -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-llvm %s -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-ppc-host.bc -o - | FileCheck --check-prefix SIMD-ONLY1 %s
  29 // RUN: %clang_cc1 -fopenmp-simd -x c++ -std=c++11 -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -emit-pch -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-ppc-host.bc -o %t %s
  30 // RUN: %clang_cc1 -fopenmp-simd -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=powerpc64le-ibm-linux-gnu -std=c++11 -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-ppc-host.bc -include-pch %t -verify -Wno-vla %s -emit-llvm -o - | FileCheck --check-prefix SIMD-ONLY1 %s
  31 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp-simd -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-llvm-bc %s -o %t-x86-host.bc
  32 // RUN: %clang_cc1 -verify -Wno-vla -fopenmp-simd -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-llvm %s -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-x86-host.bc -o - | FileCheck --check-prefix SIMD-ONLY1 %s
  33 // RUN: %clang_cc1 -fopenmp-simd -x c++ -std=c++11 -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -emit-pch -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-x86-host.bc -o %t %s
  34 // RUN: %clang_cc1 -fopenmp-simd -x c++ -triple i386-unknown-unknown -fopenmp-targets=i386-pc-linux-gnu -std=c++11 -fopenmp-is-target-device -fopenmp-host-ir-file-path %t-x86-host.bc -include-pch %t -verify -Wno-vla %s -emit-llvm -o - | FileCheck --check-prefix SIMD-ONLY1 %s
  35 // SIMD-ONLY1-NOT: {{__kmpc|__tgt}}
  36
  37 // expected-no-diagnostics
  38 #ifndef HEADER
  39 #define HEADER
  40
  41 // CHECK-DAG: [[TT:%.+]] = type { i64, i8 }
  42 // CHECK-DAG: [[ENTTY:%.+]] = type { ptr, ptr, i[[SZ:32|64]], i32, i32 }
  43
  44 // TCHECK: [[ENTTY:%.+]] = type { ptr, ptr, i{{32|64}}, i32, i32 }
  45
  46 // CHECK-DAG: [[SIZET:@.+]] = private unnamed_addr constant [2 x i64] [i64 0, i64 4]
  47 // CHECK-DAG: [[MAPT:@.+]] = private unnamed_addr constant [2 x i64] [i64 544, i64 800]
  48 // CHECK-DAG: @{{.*}} = weak constant i8 0
  49
  50 // TCHECK: @{{.+}} = weak constant [[ENTTY]]
  51 // TCHECK: @{{.+}} = {{.*}}constant [[ENTTY]]
  52 // TCHECK-NOT: @{{.+}} = weak constant [[ENTTY]]
  53
  54 template<typename tx, typename ty>
  55 struct TT{
  56   tx X;
  57   ty Y;
  58 };
  59
  60 int global;
  61 extern int global;
  62
  63 // CHECK: define {{.*}}[[FOO:@.+]](
  64 int foo(int n) {
  65   int a = 0;
  66   short aa = 0;
  67   float b[10];
  68   float bn[n];
  69   double c[5][10];
  70   double cn[5][n];
  71   TT<long long, char> d;
  72   static long *plocal;
  73
  74   // CHECK:       [[ADD:%.+]] = add nsw i32
  75   // CHECK:       store i32 [[ADD]], ptr [[DEVICE_CAP:%.+]],
  76   // CHECK:       [[GEP:%.+]] = getelementptr inbounds nuw %{{.+}}, ptr %{{.+}}, i32 0, i32 0
  77   // CHECK:       [[DEV:%.+]] = load i32, ptr [[DEVICE_CAP]],
  78   // CHECK:       store i32 [[DEV]], ptr [[GEP]],
  79   // CHECK:       [[TASK:%.+]] = call ptr @__kmpc_omp_task_alloc(ptr [[ID:@.+]], i32 [[GTID:%.+]], i32 1, i[[SZ]] {{20|40}}, i[[SZ]] 4, ptr [[TASK_ENTRY0:@.+]])
  80   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 0
  81   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 1
  82   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 2
  83   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 3
  84   // CHECK:       call void @__kmpc_omp_taskwait_deps_51(ptr [[ID]], i32 [[GTID]], i32 4, ptr %{{.+}}, i32 0, ptr null, i32 0)
  85   // CHECK:       call void @__kmpc_omp_task_begin_if0(ptr [[ID]], i32 [[GTID]], ptr [[TASK]])
  86   // CHECK:       call i32 [[TASK_ENTRY0]](i32 [[GTID]], ptr [[TASK]])
  87   // CHECK:       call void @__kmpc_omp_task_complete_if0(ptr [[ID]], i32 [[GTID]], ptr [[TASK]])
  88   #pragma omp target teams distribute device(global + a) depend(in: global) depend(out: a, b, cn[4])
  89   for (int i = 0; i < 10; ++i) {
  90   }
  91
  92   // CHECK:       [[ADD:%.+]] = add nsw i32
  93   // CHECK:       store i32 [[ADD]], ptr [[DEVICE_CAP:%.+]],
  94
  95   // CHECK:       [[BOOL:%.+]] = icmp ne i32 %{{.+}}, 0
  96   // CHECK:       br i1 [[BOOL]], label %[[THEN:.+]], label %[[ELSE:.+]]
  97   // CHECK:       [[THEN]]:
  98   // CHECK-DAG:   [[BPADDR0:%.+]] = getelementptr inbounds [2 x ptr], ptr [[BP:%.+]], i32 0, i32 0
  99   // CHECK-DAG:   [[PADDR0:%.+]] = getelementptr inbounds [2 x ptr], ptr [[P:%.+]], i32 0, i32 0
 100   // CHECK-DAG:   store ptr [[BP0:%[^,]+]], ptr [[BPADDR0]]
 101   // CHECK-DAG:   store ptr [[BP0]], ptr [[PADDR0]]
 102
 103   // CHECK-DAG:   [[BPADDR1:%.+]] = getelementptr inbounds [2 x ptr], ptr [[BP]], i32 0, i32 1
 104   // CHECK-DAG:   [[PADDR1:%.+]] = getelementptr inbounds [2 x ptr], ptr [[P]], i32 0, i32 1
 105   // CHECK-DAG:   store i[[SZ]] [[BP1:%[^,]+]], ptr [[BPADDR1]]
 106   // CHECK-DAG:   store i[[SZ]] [[BP1]], ptr [[PADDR1]]
 107   // CHECK-DAG:   getelementptr inbounds [2 x ptr], ptr [[BP]], i32 0, i32 0
 108   // CHECK-DAG:   getelementptr inbounds [2 x ptr], ptr [[P]], i32 0, i32 0
 109   // CHECK:       [[GEP:%.+]] = getelementptr inbounds nuw %{{.+}}, ptr %{{.+}}, i32 0, i32 2
 110   // CHECK:       [[DEV:%.+]] = load i32, ptr [[DEVICE_CAP]],
 111   // CHECK:       store i32 [[DEV]], ptr [[GEP]],
 112   // CHECK:       [[DEV1:%.+]] = load i32, ptr [[DEVICE_CAP]],
 113   // CHECK:       [[DEV2:%.+]] = sext i32 [[DEV1]] to i64
 114
 115   // CHECK:       [[TASK:%.+]] = call ptr @__kmpc_omp_target_task_alloc(ptr [[ID]], i32 [[GTID]], i32 1, i[[SZ]] {{104|60}}, i[[SZ]] {{16|12}}, ptr [[TASK_ENTRY1_:@.+]], i64 [[DEV2]])
 116   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 0
 117   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 1
 118   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 2
 119   // CHECK:       call i32 @__kmpc_omp_task_with_deps(ptr [[ID]], i32 [[GTID]], ptr [[TASK]], i32 3, ptr %{{.+}}, i32 0, ptr null)
 120   // CHECK:       br label %[[EXIT:.+]]
 121
 122   // CHECK:       [[ELSE]]:
 123   // CHECK-NOT:   getelementptr inbounds [2 x ptr], ptr
 124   // CHECK:       [[GEP:%.+]] = getelementptr inbounds nuw %{{.+}}, ptr %{{.+}}, i32 0, i32 2
 125   // CHECK:       [[DEV:%.+]] = load i32, ptr [[DEVICE_CAP]],
 126   // CHECK:       store i32 [[DEV]], ptr [[GEP]],
 127   // CHECK:       [[DEV1:%.+]] = load i32, ptr [[DEVICE_CAP]],
 128   // CHECK:       [[DEV2:%.+]] = sext i32 [[DEV1]] to i64
 129
 130   // CHECK:       [[TASK:%.+]] = call ptr @__kmpc_omp_target_task_alloc(ptr [[ID]], i32 [[GTID]], i32 1, i[[SZ]] {{56|28}}, i[[SZ]] {{16|12}}, ptr [[TASK_ENTRY1__:@.+]], i64 [[DEV2]])
 131   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 0
 132   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 1
 133   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 2
 134   // CHECK:       call i32 @__kmpc_omp_task_with_deps(ptr [[ID]], i32 [[GTID]], ptr [[TASK]], i32 3, ptr %{{.+}}, i32 0, ptr null)
 135   // CHECK:       br label %[[EXIT:.+]]
 136   // CHECK:       [[EXIT]]:
 137
 138   #pragma omp target teams distribute device(global + a) nowait depend(inout: global, a, bn) if(a)
 139   for (int i = 0; i < *plocal; ++i) {
 140     static int local1;
 141     *plocal = global;
 142     local1 = global;
 143   }
 144
 145   // CHECK:       [[TASK:%.+]] = call ptr @__kmpc_omp_task_alloc(ptr [[ID]], i32 [[GTID]], i32 1, i[[SZ]] {{48|24}}, i[[SZ]] 4, ptr [[TASK_ENTRY2:@.+]])
 146   // CHECK:       getelementptr %struct.kmp_depend_info, ptr %{{.+}}, i[[SZ]] 0
 147   // CHECK:       call void @__kmpc_omp_taskwait_deps_51(ptr [[ID]], i32 [[GTID]], i32 1, ptr %{{.+}}, i32 0, ptr null, i32 0)
 148   // CHECK:       call void @__kmpc_omp_task_begin_if0(ptr [[ID]], i32 [[GTID]], ptr [[TASK]])
 149   // CHECK:       call i32 [[TASK_ENTRY2]](i32 [[GTID]], ptr [[TASK]])
 150   // CHECK:       call void @__kmpc_omp_task_complete_if0(ptr [[ID]], i32 [[GTID]], ptr [[TASK]])
 151   #pragma omp target teams distribute if(0) firstprivate(global) depend(out:global)
 152   for (int i = 0; i < global; ++i) {
 153     global += 1;
 154   }
 155
 156   return a;
 157 }
 158
 159 // Check that the offloading functions are emitted and that the arguments are
 160 // correct and loaded correctly for the target regions in foo().
 161
 162 // CHECK:       define internal void [[HVT0:@.+]]()
 163
 164 // CHECK:       define internal{{.*}} i32 [[TASK_ENTRY0]](i32{{.*}}, ptr noalias noundef %1)
 165 // CHECK:       store ptr null, ptr %
 166 // CHECK:       [[DEVICE_CAP:%.+]] = load ptr,
 167 // CHECK:       [[DEV:%.+]] = load i32, ptr [[DEVICE_CAP]],
 168 // CHECK:       [[DEVICE:%.+]] = sext i32 [[DEV]] to i64
 169 // CHECK:       [[RET:%.+]] = call i32 @__tgt_target_kernel(ptr @{{.+}}, i64 [[DEVICE]], i32 0, i32 0, ptr @.{{.+}}.region_id, ptr %{{.+}})
 170 // CHECK-NEXT:  [[ERROR:%.+]] = icmp ne i32 [[RET]], 0
 171 // CHECK-NEXT:  br i1 [[ERROR]], label %[[FAIL:[^,]+]], label %[[END:[^,]+]]
 172 // CHECK:       [[FAIL]]
 173 // CHECK:       call void [[HVT0]]()
 174 // CHECK-NEXT:  br label %[[END]]
 175 // CHECK:       [[END]]
 176 // CHECK:       ret i32 0
 177
 178 // CHECK:       define internal void [[HVT1:@.+]](ptr noundef %{{.+}}, i[[SZ]] noundef %{{.+}})
 179
 180 // CHECK:       define internal{{.*}} i32 [[TASK_ENTRY1_]](i32{{.*}}, ptr noalias noundef %1)
 181 // CHECK:       call void {{%.*}}(
 182 // CHECK:       [[DEVICE_CAP:%.+]] = getelementptr inbounds nuw %{{.+}}, ptr %{{.+}}, i32 0, i32 2
 183 // CHECK:       [[DEV:%.+]] = load i32, ptr [[DEVICE_CAP]],
 184 // CHECK:       [[DEVICE:%.+]] = sext i32 [[DEV]] to i64
 185 // CHECK:       [[RET:%.+]] = call i32 @__tgt_target_kernel(ptr @{{.+}}, i64 [[DEVICE]], i32 0, i32 0, ptr @.{{.+}}.region_id, ptr %{{.+}})
 186
 187 // CHECK:       [[ERROR:%.+]] = icmp ne i32 [[RET]], 0
 188 // CHECK-NEXT:  br i1 [[ERROR]], label %[[FAIL:[^,]+]], label %[[END:[^,]+]]
 189 // CHECK:       [[FAIL]]
 190 // CHECK:       [[BP0:%.+]] = load ptr, ptr %
 191 // CHECK:       [[BP1_I32:%.+]] = load i32, ptr @
 192 // CHECK-64:    store i32 [[BP1_I32]], ptr [[BP1_PTR:%[^,]+]],
 193 // CHECK-32:    store i32 [[BP1_I32]], ptr [[BP1_PTR:%[^,]+]],
 194 // CHECK:       [[BP1:%.+]] = load i[[SZ]], ptr [[BP1_PTR]],
 195 // CHECK:       call void [[HVT1]](ptr [[BP0]], i[[SZ]] [[BP1]])
 196 // CHECK-NEXT:  br label %[[END]]
 197 // CHECK:       [[END]]
 198 // CHECK:       ret i32 0
 199
 200 // CHECK:       define internal{{.*}} i32 [[TASK_ENTRY1__]](i32{{.*}}, ptr noalias noundef %1)
 201 // CHECK:       call void {{%.*}}(
 202 // CHECK:       [[DEVICE_CAP:%.+]] = getelementptr inbounds nuw %{{.+}}, ptr %{{.+}}, i32 0, i32 2
 203 // CHECK:       [[BP0:%.+]] = load ptr, ptr %
 204 // CHECK:       [[BP1_I32:%.+]] = load i32, ptr @
 205 // CHECK-64:    store i32 [[BP1_I32]], ptr [[BP1_PTR:%[^,]+]],
 206 // CHECK-32:    store i32 [[BP1_I32]], ptr [[BP1_PTR:%[^,]+]],
 207 // CHECK:       [[BP1:%.+]] = load i[[SZ]], ptr [[BP1_PTR]],
 208 // CHECK:       call void [[HVT1]](ptr [[BP0]], i[[SZ]] [[BP1]])
 209 // CHECK:       ret i32 0
 210
 211 // CHECK:       define internal void [[HVT2:@.+]](i[[SZ]] noundef %{{.+}})
 212 // Create stack storage and store argument in there.
 213 // CHECK:       [[AA_ADDR:%.+]] = alloca i[[SZ]], align
 214 // CHECK:       store i[[SZ]] %{{.+}}, ptr [[AA_ADDR]], align
 215 // CHECK-64:    load i32, ptr [[AA_ADDR]], align
 216 // CHECK-32:    load i32, ptr [[AA_ADDR]], align
 217
 218 // CHECK:       define internal{{.*}} i32 [[TASK_ENTRY2]](i32{{.*}}, ptr noalias noundef %1)
 219 // CHECK:       call void {{%.*}}(
 220 // CHECK:       [[BP1_I32:%.+]] = load i32, ptr %
 221 // CHECK-64:    store i32 [[BP1_I32]], ptr [[BP1_PTR:%[^,]+]],
 222 // CHECK-32:    store i32 [[BP1_I32]], ptr [[BP1_PTR:%[^,]+]],
 223 // CHECK:       [[BP1:%.+]] = load i[[SZ]], ptr [[BP1_PTR]],
 224 // CHECK:       call void [[HVT2]](i[[SZ]] [[BP1]])
 225 // CHECK:       ret i32 0
 226
 227
 228 #endif