clang/test/CodeGen/builtin-expect-with-probability.cpp

   1 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -O1 -disable-llvm-passes | FileCheck %s --check-prefix=ALL --check-prefix=O1
   2 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -O0 | FileCheck %s --check-prefix=ALL --check-prefix=O0
   3 extern int global;
   4
   5 int expect_taken(int x) {
   6 // ALL-LABEL: expect_taken
   7 // O1:        call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 1, double 9.000000e-01)
   8 // O0-NOT:    @llvm.expect.with.probability
   9
  10   if (__builtin_expect_with_probability(x == 100, 1, 0.9)) {
  11     return 0;
  12   }
  13   return x;
  14 }
  15
  16 int expect_not_taken(int x) {
  17 // ALL-LABEL: expect_not_taken
  18 // O1:        call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 0, double 9.000000e-01)
  19 // O0-NOT:    @llvm.expect.with.probability
  20
  21   if (__builtin_expect_with_probability(x == 100, 0, 0.9)) {
  22     return 0;
  23   }
  24   return x;
  25 }
  26
  27 struct S {
  28   static constexpr int prob = 1;
  29 };
  30
  31 template<typename T>
  32 int expect_taken_template(int x) {
  33 // ALL-LABEL: expect_taken_template
  34 // O1:        call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 1, double 1.000000e+00)
  35 // O0-NOT:    @llvm.expect.with.probability
  36
  37         if (__builtin_expect_with_probability (x == 100, 1, T::prob)) {
  38                 return 0;
  39         }
  40         return x;
  41 }
  42
  43 int f() {
  44   return expect_taken_template<S>(global);
  45 }
  46
  47 int x;
  48 extern "C" {
  49   int y(void);
  50 }
  51 void foo();
  52
  53 void expect_value_side_effects() {
  54 // ALL-LABEL: expect_value_side_effects
  55 // ALL: [[CALL:%.*]] = call i32 @y
  56 // O1:  [[SEXT:%.*]] = sext i32 [[CALL]] to i64
  57 // O1:  call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 [[SEXT]], double 6.000000e-01)
  58 // O0-NOT: @llvm.expect.with.probability
  59
  60   if (__builtin_expect_with_probability(x, y(), 0.6))
  61     foo();
  62 }
  63
  64 int switch_cond(int x) {
  65 // ALL-LABEL: switch_cond
  66 // O1:        call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 1, double 8.000000e-01)
  67 // O0-NOT:    @llvm.expect.with.probability
  68
  69   switch (__builtin_expect_with_probability(x, 1, 0.8)) {
  70   case 0:
  71     x = x + 0;
  72   case 1:
  73     x = x + 1;
  74   case 2:
  75     x = x + 2;
  76   case 5:
  77     x = x + 5;
  78   default:
  79     x = x + 6;
  80   }
  81   return x;
  82 }
  83
  84 constexpr double prob = 0.8;
  85
  86 int variable_expected(int stuff) {
  87 // ALL-LABEL: variable_expected
  88 // O1: call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 {{%.*}}, double 8.000000e-01)
  89 // O0-NOT: @llvm.expect.with.probability
  90
  91   int res = 0;
  92
  93   switch(__builtin_expect_with_probability(stuff, stuff, prob)) {
  94     case 0:
  95       res = 1;
  96       break;
  97     default:
  98       break;
  99   }
 100   return res;
 101 }