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))
test_fdiv(float A)22 float 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))
test_distributivity(float A,float B,float C)32 float 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))
test_associativity(float A,float B,float C)50 float 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))
test_simplify_fp_operations(float A,float B)74 float 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))
test_simplify_fp_operations_2(float A,float B,float C)87 float 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
main()98 int main() {
99 float result = test_fdiv(4.0f);
100 result += test_distributivity(4.0f, 5.0f, 6.0f);
101 result += test_associativity(4.0f, 5.0f, 6.0f);
102 result += test_simplify_fp_operations(8.25, result);
103 result += test_simplify_fp_operations_2(9.12, result, 1002.111);
104 return static_cast<int>(result);
105 }
106