donotoptimize_assembly_test.cc
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#include <benchmark/benchmark.h>
#ifdef __clang__
#pragma clang diagnostic ignored "-Wreturn-type"
#endif
extern "C" {
extern int ExternInt;
extern int ExternInt2;
extern int ExternInt3;
inline int Add42(int x) { return x + 42; }
struct NotTriviallyCopyable {
NotTriviallyCopyable();
explicit NotTriviallyCopyable(int x) : value(x) {}
NotTriviallyCopyable(NotTriviallyCopyable const&);
int value;
};
struct Large {
int value;
int data[2];
};
}
// CHECK-LABEL: test_with_rvalue:
extern "C" void test_with_rvalue() {
benchmark::DoNotOptimize(Add42(0));
// CHECK: movl $42, %eax
// CHECK: ret
}
// CHECK-LABEL: test_with_large_rvalue:
extern "C" void test_with_large_rvalue() {
benchmark::DoNotOptimize(Large{ExternInt, {ExternInt, ExternInt}});
// CHECK: ExternInt(%rip)
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG:[a-z]+]]
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG]])
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG]])
// CHECK: ret
}
// CHECK-LABEL: test_with_non_trivial_rvalue:
extern "C" void test_with_non_trivial_rvalue() {
benchmark::DoNotOptimize(NotTriviallyCopyable(ExternInt));
// CHECK: mov{{l|q}} ExternInt(%rip)
// CHECK: ret
}
// CHECK-LABEL: test_with_lvalue:
extern "C" void test_with_lvalue() {
int x = 101;
benchmark::DoNotOptimize(x);
// CHECK-GNU: movl $101, %eax
// CHECK-CLANG: movl $101, -{{[0-9]+}}(%[[REG:[a-z]+]])
// CHECK: ret
}
// CHECK-LABEL: test_with_large_lvalue:
extern "C" void test_with_large_lvalue() {
Large L{ExternInt, {ExternInt, ExternInt}};
benchmark::DoNotOptimize(L);
// CHECK: ExternInt(%rip)
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG:[a-z]+]])
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG]])
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG]])
// CHECK: ret
}
// CHECK-LABEL: test_with_non_trivial_lvalue:
extern "C" void test_with_non_trivial_lvalue() {
NotTriviallyCopyable NTC(ExternInt);
benchmark::DoNotOptimize(NTC);
// CHECK: ExternInt(%rip)
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG:[a-z]+]])
// CHECK: ret
}
// CHECK-LABEL: test_with_const_lvalue:
extern "C" void test_with_const_lvalue() {
const int x = 123;
benchmark::DoNotOptimize(x);
// CHECK: movl $123, %eax
// CHECK: ret
}
// CHECK-LABEL: test_with_large_const_lvalue:
extern "C" void test_with_large_const_lvalue() {
const Large L{ExternInt, {ExternInt, ExternInt}};
benchmark::DoNotOptimize(L);
// CHECK: ExternInt(%rip)
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG:[a-z]+]])
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG]])
// CHECK: movl %eax, -{{[0-9]+}}(%[[REG]])
// CHECK: ret
}
// CHECK-LABEL: test_with_non_trivial_const_lvalue:
extern "C" void test_with_non_trivial_const_lvalue() {
const NotTriviallyCopyable Obj(ExternInt);
benchmark::DoNotOptimize(Obj);
// CHECK: mov{{q|l}} ExternInt(%rip)
// CHECK: ret
}
// CHECK-LABEL: test_div_by_two:
extern "C" int test_div_by_two(int input) {
int divisor = 2;
benchmark::DoNotOptimize(divisor);
return input / divisor;
// CHECK: movl $2, [[DEST:.*]]
// CHECK: idivl [[DEST]]
// CHECK: ret
}
// CHECK-LABEL: test_inc_integer:
extern "C" int test_inc_integer() {
int x = 0;
for (int i=0; i < 5; ++i)
benchmark::DoNotOptimize(++x);
// CHECK: movl $1, [[DEST:.*]]
// CHECK: {{(addl \$1,|incl)}} [[DEST]]
// CHECK: {{(addl \$1,|incl)}} [[DEST]]
// CHECK: {{(addl \$1,|incl)}} [[DEST]]
// CHECK: {{(addl \$1,|incl)}} [[DEST]]
// CHECK-CLANG: movl [[DEST]], %eax
// CHECK: ret
return x;
}
// CHECK-LABEL: test_pointer_rvalue
extern "C" void test_pointer_rvalue() {
// CHECK: movl $42, [[DEST:.*]]
// CHECK: leaq [[DEST]], %rax
// CHECK-CLANG: movq %rax, -{{[0-9]+}}(%[[REG:[a-z]+]])
// CHECK: ret
int x = 42;
benchmark::DoNotOptimize(&x);
}
// CHECK-LABEL: test_pointer_const_lvalue:
extern "C" void test_pointer_const_lvalue() {
// CHECK: movl $42, [[DEST:.*]]
// CHECK: leaq [[DEST]], %rax
// CHECK-CLANG: movq %rax, -{{[0-9]+}}(%[[REG:[a-z]+]])
// CHECK: ret
int x = 42;
int * const xp = &x;
benchmark::DoNotOptimize(xp);
}
// CHECK-LABEL: test_pointer_lvalue:
extern "C" void test_pointer_lvalue() {
// CHECK: movl $42, [[DEST:.*]]
// CHECK: leaq [[DEST]], %rax
// CHECK-CLANG: movq %rax, -{{[0-9]+}}(%[[REG:[a-z+]+]])
// CHECK: ret
int x = 42;
int *xp = &x;
benchmark::DoNotOptimize(xp);
}