clang/test/CodeGen/builtin-expect.c

   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
   4 // In all tests, make sure that no expect is generated if optimizations are off.
   5 // If optimizations are on, generate the correct expect and preserve other necessary operations.
   6
   7 int expect_taken(int x) {
   8 // ALL-LABEL: define{{.*}} i32 @expect_taken
   9 // O1:        call i64 @llvm.expect.i64(i64 {{%.*}}, i64 1)
  10 // O0-NOT:    @llvm.expect
  11
  12   if (__builtin_expect (x, 1))
  13     return 0;
  14   return x;
  15 }
  16
  17
  18 int expect_not_taken(int x) {
  19 // ALL-LABEL: define{{.*}} i32 @expect_not_taken
  20 // O1:        call i64 @llvm.expect.i64(i64 {{%.*}}, i64 0)
  21 // O0-NOT:    @llvm.expect
  22
  23   if (__builtin_expect (x, 0))
  24     return 0;
  25   return x;
  26 }
  27
  28
  29 int x;
  30 int y(void);
  31 void foo(void);
  32
  33 void expect_value_side_effects(void) {
  34 // ALL-LABEL: define{{.*}} void @expect_value_side_effects()
  35 // ALL:       [[CALL:%.*]] = call i32 @y
  36 // O1:        [[SEXT:%.*]] = sext i32 [[CALL]] to i64
  37 // O1:        call i64 @llvm.expect.i64(i64 {{%.*}}, i64 [[SEXT]])
  38 // O0-NOT:    @llvm.expect
  39
  40   if (__builtin_expect (x, y()))
  41     foo ();
  42 }
  43
  44
  45 // Make sure that issigprocmask() is called before bar()?
  46 // There's no compare, so there's nothing to expect?
  47 // rdar://9330105
  48 void isigprocmask(void);
  49 long bar(void);
  50
  51 int main(void) {
  52 // ALL-LABEL: define{{.*}} i32 @main()
  53 // ALL:       call void @isigprocmask()
  54 // ALL:       [[CALL:%.*]] = call i64 @bar()
  55 // O1:        call i64 @llvm.expect.i64(i64 0, i64 [[CALL]])
  56 // O0-NOT:    @llvm.expect
  57
  58   (void) __builtin_expect((isigprocmask(), 0), bar());
  59 }
  60
  61
  62 int switch_cond(int x) {
  63 // ALL-LABEL: define{{.*}} i32 @switch_cond
  64 // O1:        call i64 @llvm.expect.i64(i64 {{%.*}}, i64 5)
  65 // O0-NOT:    @llvm.expect
  66
  67   switch(__builtin_expect(x, 5)) {
  68   default:
  69     return 0;
  70   case 0:
  71   case 1:
  72   case 2:
  73     return 1;
  74   case 5:
  75     return 5;
  76   };
  77
  78   return 0;
  79 }
  80
  81 int variable_expected(int stuff) {
  82 // ALL-LABEL: define{{.*}} i32 @variable_expected(
  83 // O1: call i64 @llvm.expect.i64(i64 {{%.*}}, i64 {{%.*}})
  84 // O0-NOT: @llvm.expect
  85
  86   int res = 0;
  87
  88   switch (__builtin_expect(stuff, stuff)) {
  89   case 0:
  90     res = 1;
  91     break;
  92   default:
  93     break;
  94   }
  95
  96   return res;
  97 }