builtin-expect-with-probability.cpp
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// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -O1 -disable-llvm-passes | FileCheck %s --check-prefix=ALL --check-prefix=O1
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -O0 | FileCheck %s --check-prefix=ALL --check-prefix=O0
extern int global;
int expect_taken(int x) {
// ALL-LABEL: expect_taken
// O1: call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 1, double 9.000000e-01)
// O0-NOT: @llvm.expect.with.probability
if (__builtin_expect_with_probability(x == 100, 1, 0.9)) {
return 0;
}
return x;
}
int expect_not_taken(int x) {
// ALL-LABEL: expect_not_taken
// O1: call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 0, double 9.000000e-01)
// O0-NOT: @llvm.expect.with.probability
if (__builtin_expect_with_probability(x == 100, 0, 0.9)) {
return 0;
}
return x;
}
struct S {
static constexpr int prob = 1;
};
template<typename T>
int expect_taken_template(int x) {
// ALL-LABEL: expect_taken_template
// O1: call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 1, double 1.000000e+00)
// O0-NOT: @llvm.expect.with.probability
if (__builtin_expect_with_probability (x == 100, 1, T::prob)) {
return 0;
}
return x;
}
int f() {
return expect_taken_template<S>(global);
}
int x;
extern "C" {
int y(void);
}
void foo();
void expect_value_side_effects() {
// ALL-LABEL: expect_value_side_effects
// ALL: [[CALL:%.*]] = call i32 @y
// O1: [[SEXT:%.*]] = sext i32 [[CALL]] to i64
// O1: call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 [[SEXT]], double 6.000000e-01)
// O0-NOT: @llvm.expect.with.probability
if (__builtin_expect_with_probability(x, y(), 0.6))
foo();
}
int switch_cond(int x) {
// ALL-LABEL: switch_cond
// O1: call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 1, double 8.000000e-01)
// O0-NOT: @llvm.expect.with.probability
switch (__builtin_expect_with_probability(x, 1, 0.8)) {
case 0:
x = x + 0;
case 1:
x = x + 1;
case 2:
x = x + 2;
case 5:
x = x + 5;
default:
x = x + 6;
}
return x;
}
constexpr double prob = 0.8;
int variable_expected(int stuff) {
// ALL-LABEL: variable_expected
// O1: call i64 @llvm.expect.with.probability.i64(i64 {{%.*}}, i64 {{%.*}}, double 8.000000e-01)
// O0-NOT: @llvm.expect.with.probability
int res = 0;
switch(__builtin_expect_with_probability(stuff, stuff, prob)) {
case 0:
res = 1;
break;
default:
break;
}
return res;
}