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| 1 | +// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -verify=expected,default %s |
| 2 | +// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -analyzer-config inline-functions-with-ambiguous-loops=true -verify=expected,enabled %s |
| 3 | + |
| 4 | +// This file tests some heuristics in the engine that put functions on a |
| 5 | +// "do not inline" list if their analyisis reaches the `analyzer-max-loop` |
| 6 | +// limit (by default 4 iterations) in a loop. This was almost surely intended |
| 7 | +// as memoization optimization for the "retry without inlining" fallback (if we |
| 8 | +// had to retry once, next time don't even try inlining), but aggressively |
| 9 | +// oversteps the "natural" scope: reaching 4 iterations on _one particular_ |
| 10 | +// execution path does not imply that each path would need "retry without |
| 11 | +// inlining" especially if a different call receives different arguments. |
| 12 | +// |
| 13 | +// This heuristic significantly affects the scope/depth of the analysis (and |
| 14 | +// therefore the execution time) because without this limitation on the |
| 15 | +// inlining significantly more entry points would be able to exhaust their |
| 16 | +// `max-nodes` quota. (Trivial thin wrappers around big complex functions are |
| 17 | +// common in many projects.) |
| 18 | +// |
| 19 | +// Unfortunately, this arbitrary heuristic strongly relies on the current loop |
| 20 | +// handling model and its many limitations, so improvements in loop handling |
| 21 | +// can cause surprising slowdowns by reducing the "do not inline" blacklist. |
| 22 | +// In the tests "FIXME-BUT-NEEDED" comments mark "problematic" (aka buggy) |
| 23 | +// analyzer behavior which cannot be fixed without also improving the |
| 24 | +// heuristics for (not) inlining large functions. |
| 25 | + |
| 26 | + int getNum(void); // Get an unknown symbolic number. |
| 27 | + |
| 28 | +void clang_analyzer_dump(int arg); |
| 29 | + |
| 30 | +//----------------------------------------------------------------------------- |
| 31 | +// Simple case: inlined function never reaches `analyzer-max-loop`, so it is |
| 32 | +// always inlined. |
| 33 | + |
| 34 | +int inner_simple(int callIdx) { |
| 35 | + clang_analyzer_dump(callIdx); // expected-warning {{1 S32}} |
| 36 | + // expected-warning@-1 {{2 S32}} |
| 37 | + return 42; |
| 38 | +} |
| 39 | + |
| 40 | +int outer_simple(void) { |
| 41 | + int x = inner_simple(1); |
| 42 | + int y = inner_simple(2); |
| 43 | + return 53 / (x - y); // expected-warning {{Division by zero}} |
| 44 | +} |
| 45 | + |
| 46 | +//----------------------------------------------------------------------------- |
| 47 | +// Inlined function always reaches `analyzer-max-loop`, which stops the |
| 48 | +// analysis on that path and puts the function on the "do not inline" list. |
| 49 | + |
| 50 | +int inner_fixed_loop_1(int callIdx) { |
| 51 | + int i; |
| 52 | + clang_analyzer_dump(callIdx); // expected-warning {{1 S32}} |
| 53 | + for (i = 0; i < 10; i++); // FIXME-BUT-NEEDED: This stops the analysis. |
| 54 | + clang_analyzer_dump(callIdx); // no-warning |
| 55 | + return 42; |
| 56 | +} |
| 57 | + |
| 58 | +int outer_fixed_loop_1(void) { |
| 59 | + int x = inner_fixed_loop_1(1); |
| 60 | + int y = inner_fixed_loop_1(2); |
| 61 | + |
| 62 | + // FIXME-BUT-NEEDED: The analysis doesn't reach this zero division. |
| 63 | + return 53 / (x - y); // no-warning |
| 64 | +} |
| 65 | + |
| 66 | +//----------------------------------------------------------------------------- |
| 67 | +// Inlined function always reaches `analyzer-max-loop`; inlining is prevented |
| 68 | +// even for different entry points. |
| 69 | +// NOTE: the analyzer happens to analyze the entry points in a reversed order, |
| 70 | +// so `outer_2_fixed_loop_2` is analyzed first and it will be the one which is |
| 71 | +// able to inline the inner function. |
| 72 | + |
| 73 | +int inner_fixed_loop_2(int callIdx) { |
| 74 | + // Identical copy of inner_fixed_loop_1. |
| 75 | + int i; |
| 76 | + clang_analyzer_dump(callIdx); // expected-warning {{2 S32}} |
| 77 | + for (i = 0; i < 10; i++); // FIXME-BUT-NEEDED: This stops the analysis. |
| 78 | + clang_analyzer_dump(callIdx); // no-warning |
| 79 | + return 42; |
| 80 | +} |
| 81 | + |
| 82 | +int outer_1_fixed_loop_2(void) { |
| 83 | + return inner_fixed_loop_2(1); |
| 84 | +} |
| 85 | + |
| 86 | +int outer_2_fixed_loop_2(void) { |
| 87 | + return inner_fixed_loop_2(2); |
| 88 | +} |
| 89 | + |
| 90 | +//----------------------------------------------------------------------------- |
| 91 | +// Inlined function reaches `analyzer-max-loop` only in its second call. The |
| 92 | +// function is inlined twice but the second call doesn't finish and ends up |
| 93 | +// being conservatively evaluated. |
| 94 | + |
| 95 | +int inner_parametrized_loop_1(int count) { |
| 96 | + int i; |
| 97 | + clang_analyzer_dump(count); // expected-warning {{2 S32}} |
| 98 | + // expected-warning@-1 {{10 S32}} |
| 99 | + for (i = 0; i < count; i++); |
| 100 | + // FIXME-BUT-NEEDED: This loop stops the analysis when count >=4. |
| 101 | + clang_analyzer_dump(count); // expected-warning {{2 S32}} |
| 102 | + return 42; |
| 103 | +} |
| 104 | + |
| 105 | +int outer_parametrized_loop_1(void) { |
| 106 | + int x = inner_parametrized_loop_1(2); |
| 107 | + int y = inner_parametrized_loop_1(10); |
| 108 | + |
| 109 | + // FIXME-BUT-NEEDED: The analysis doesn't reach this zero division. |
| 110 | + return 53 / (x - y); // no-warning |
| 111 | +} |
| 112 | + |
| 113 | +//----------------------------------------------------------------------------- |
| 114 | +// Inlined function reaches `analyzer-max-loop` on its first call, so the |
| 115 | +// second call isn't inlined (although it could be fully evaluated). |
| 116 | + |
| 117 | +int inner_parametrized_loop_2(int count) { |
| 118 | + // Identical copy of inner_parametrized_loop_1. |
| 119 | + int i; |
| 120 | + clang_analyzer_dump(count); // expected-warning {{10 S32}} |
| 121 | + for (i = 0; i < count; i++); |
| 122 | + // FIXME-BUT-NEEDED: This loop stops the analysis when count >=4. |
| 123 | + clang_analyzer_dump(count); // no-warning |
| 124 | + return 42; |
| 125 | +} |
| 126 | + |
| 127 | +int outer_parametrized_loop_2(void) { |
| 128 | + int y = inner_parametrized_loop_2(10); |
| 129 | + int x = inner_parametrized_loop_2(2); |
| 130 | + |
| 131 | + // FIXME-BUT-NEEDED: The analysis doesn't reach this zero division. |
| 132 | + return 53 / (x - y); // no-warning |
| 133 | +} |
| 134 | + |
| 135 | +//----------------------------------------------------------------------------- |
| 136 | +// Inlined function may or may not reach `analyzer-max-loop` depending on an |
| 137 | +// ambiguous check before the loop. This is very similar to the "fixed loop" |
| 138 | +// cases: the function is placed on the "don't inline" list when any execution |
| 139 | +// path reaches `analyzer-max-loop` (even if other execution paths reach the |
| 140 | +// end of the function). |
| 141 | +// NOTE: This is tested with two separate entry points to ensure that one |
| 142 | +// inlined call is fully evaluated before we try to inline the other call. |
| 143 | +// NOTE: the analyzer happens to analyze the entry points in a reversed order, |
| 144 | +// so `outer_2_conditional_loop` is analyzed first and it will be the one which |
| 145 | +// is able to inline the inner function. |
| 146 | + |
| 147 | +int inner_conditional_loop(int callIdx) { |
| 148 | + int i; |
| 149 | + clang_analyzer_dump(callIdx); // expected-warning {{2 S32}} |
| 150 | + if (getNum() == 777) { |
| 151 | + for (i = 0; i < 10; i++); |
| 152 | + } |
| 153 | + clang_analyzer_dump(callIdx); // expected-warning {{2 S32}} |
| 154 | + return 42; |
| 155 | +} |
| 156 | + |
| 157 | +int outer_1_conditional_loop(void) { |
| 158 | + return inner_conditional_loop(1); |
| 159 | +} |
| 160 | + |
| 161 | +int outer_2_conditional_loop(void) { |
| 162 | + return inner_conditional_loop(2); |
| 163 | +} |
| 164 | + |
| 165 | +//----------------------------------------------------------------------------- |
| 166 | +// Inlined function executes an ambiguous loop that may or may not reach |
| 167 | +// `analyzer-max-loop`. Historically, before the "don't assume third iteration" |
| 168 | +// commit (bb27d5e5c6b194a1440b8ac4e5ace68d0ee2a849) this worked like the |
| 169 | +// `conditional_loop` cases: the analyzer was able to find a path reaching |
| 170 | +// `analyzer-max-loop` so inlining was disabled. After that commit the analyzer |
| 171 | +// does not _assume_ a third (or later) iteration (i.e. does not enter those |
| 172 | +// iterations if the loop condition is an unknown value), so e.g. this test |
| 173 | +// function does not reach `analyzer-max-loop` iterations and the inlining is |
| 174 | +// not disabled. |
| 175 | +// Unfortunately this change significantly increased the workload and |
| 176 | +// runtime of the analyzer (more entry points used up their budget), so the |
| 177 | +// option `inline-functions-with-ambiguous-loops` was introduced and disabled |
| 178 | +// by default to suppress the inlining in situations where the "don't assume |
| 179 | +// third iteration" logic activates. |
| 180 | +// NOTE: This is tested with two separate entry points to ensure that one |
| 181 | +// inlined call is fully evaluated before we try to inline the other call. |
| 182 | +// NOTE: the analyzer happens to analyze the entry points in a reversed order, |
| 183 | +// so `outer_2_ambiguous_loop` is analyzed first and it will be the one which |
| 184 | +// is able to inline the inner function. |
| 185 | + |
| 186 | +int inner_ambiguous_loop(int callIdx) { |
| 187 | + int i; |
| 188 | + clang_analyzer_dump(callIdx); // default-warning {{2 S32}} |
| 189 | + // enabled-warning@-1 {{1 S32}} |
| 190 | + // enabled-warning@-2 {{2 S32}} |
| 191 | + for (i = 0; i < getNum(); i++); |
| 192 | + return i; |
| 193 | +} |
| 194 | + |
| 195 | +int outer_1_ambiguous_loop(void) { |
| 196 | + return inner_ambiguous_loop(1); |
| 197 | +} |
| 198 | +int outer_2_ambiguous_loop(void) { |
| 199 | + return inner_ambiguous_loop(2); |
| 200 | +} |
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