1// RUN: %clang++ -std=gnu++11 -O2 -ffast-math -g %s -o %t
2// RUN: %dexter --fail-lt 1.0 -w \
3// RUN: --binary %t --debugger 'lldb' -- %s
4// RUN: %clang++ -std=gnu++11 -O0 -ffast-math -g %s -o %t
5// RUN: %dexter --fail-lt 1.0 -w \
6// RUN: --binary %t --debugger 'lldb' -- %s
7
8// REQUIRES: lldb
9// Currently getting intermittent failures on darwin.
10// UNSUPPORTED: system-windows, system-darwin
11
12//// Check that the debugging experience with __attribute__((optnone)) at O2
13//// matches O0. Test scalar floating point arithmetic with -ffast-math.
14
15//// Example of strength reduction.
16//// The division by 10.0f can be rewritten as a multiply by 0.1f.
17//// A / 10.f ==> A * 0.1f
18//// This is safe with fastmath since we treat the two operations
19//// as equally precise. However we don't want this to happen
20//// with optnone.
21__attribute__((optnone))
22float test_fdiv(float A) {
23 float result;
24 result = A / 10.f; // DexLabel('fdiv_assign')
25 return result; // DexLabel('fdiv_ret')
26}
27// DexExpectWatchValue('A', 4, on_line=ref('fdiv_assign'))
28// DexExpectWatchValue('result', '0.400000006', on_line=ref('fdiv_ret'))
29
30//// (A * B) - (A * C) ==> A * (B - C)
31__attribute__((optnone))
32float test_distributivity(float A, float B, float C) {
33 float result;
34 float op1 = A * B;
35 float op2 = A * C; // DexLabel('distributivity_op2')
36 result = op1 - op2; // DexLabel('distributivity_result')
37 return result; // DexLabel('distributivity_ret')
38}
39// DexExpectWatchValue('op1', '20', on_line=ref('distributivity_op2'))
40// DexExpectWatchValue('op2', '24', on_line=ref('distributivity_result'))
41// DexExpectWatchValue('result', '-4', on_line=ref('distributivity_ret'))
42
43//// (A + B) + C == A + (B + C)
44//// therefore, ((A + B) + C) + (A + (B + C)))
45//// can be rewritten as
46//// 2.0f * ((A + B) + C)
47//// Clang is currently unable to spot this optimization
48//// opportunity with fastmath.
49__attribute__((optnone))
50float test_associativity(float A, float B, float C) {
51 float result;
52 float op1 = A + B;
53 float op2 = B + C;
54 op1 += C; // DexLabel('associativity_op1')
55 op2 += A;
56 result = op1 + op2; // DexLabel('associativity_result')
57 return result; // DexLabel('associativity_ret')
58}
59// DexExpectWatchValue('op1', '9', '15', from_line=ref('associativity_op1'), to_line=ref('associativity_result'))
60// DexExpectWatchValue('op2', '11', '15', from_line=ref('associativity_op1'), to_line=ref('associativity_result'))
61// DexExpectWatchValue('result', '30', on_line=ref('associativity_ret'))
62
63//// With fastmath, the ordering of instructions doesn't matter
64//// since we work under the assumption that there is no loss
65//// in precision. This simplifies things for the optimizer which
66//// can then decide to reorder instructions and fold
67//// redundant operations like this:
68//// A += 5.0f
69//// A -= 5.0f
70//// -->
71//// A
72//// This function can be simplified to a return A + B.
73__attribute__((optnone))
74float test_simplify_fp_operations(float A, float B) {
75 float result = A + 10.0f; // DexLabel('fp_operations_result')
76 result += B; // DexLabel('fp_operations_add')
77 result -= 10.0f;
78 return result; // DexLabel('fp_operations_ret')
79}
80// DexExpectWatchValue('A', '8.25', on_line=ref('fp_operations_result'))
81// DexExpectWatchValue('B', '26.3999996', on_line=ref('fp_operations_result'))
82// DexExpectWatchValue('result', '18.25', '44.6500015', '34.6500015', from_line=ref('fp_operations_add'), to_line=ref('fp_operations_ret'))
83
84//// Again, this is a simple return A + B.
85//// Clang is unable to spot the opportunity to fold the code sequence.
86__attribute__((optnone))
87float test_simplify_fp_operations_2(float A, float B, float C) {
88 float result = A + C; // DexLabel('fp_operations_2_result')
89 result += B;
90 result -= C; // DexLabel('fp_operations_2_subtract')
91 return result; // DexLabel('fp_operations_2_ret')
92}
93// DexExpectWatchValue('A', '9.11999988', on_line=ref('fp_operations_2_result'))
94// DexExpectWatchValue('B', '61.050003', on_line=ref('fp_operations_2_result'))
95// DexExpectWatchValue('C', '1002.11102', on_line=ref('fp_operations_2_result'))
96// DexExpectWatchValue('result', '1072.28101', '70.1699829', from_line=ref('fp_operations_2_subtract'), to_line=ref('fp_operations_2_ret'))
97
98int main() {
99 float result = test_fdiv(A: 4.0f);
100 result += test_distributivity(A: 4.0f, B: 5.0f, C: 6.0f);
101 result += test_associativity(A: 4.0f, B: 5.0f, C: 6.0f);
102 result += test_simplify_fp_operations(A: 8.25, B: result);
103 result += test_simplify_fp_operations_2(A: 9.12, B: result, C: 1002.111);
104 return static_cast<int>(result);
105}
106

source code of cross-project-tests/debuginfo-tests/dexter-tests/optnone-fastmath.cpp