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Diffstat (limited to 'clang/test/Analysis/idempotent-operations.c')
| -rw-r--r-- | clang/test/Analysis/idempotent-operations.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/clang/test/Analysis/idempotent-operations.c b/clang/test/Analysis/idempotent-operations.c new file mode 100644 index 0000000..6cc9a01 --- /dev/null +++ b/clang/test/Analysis/idempotent-operations.c @@ -0,0 +1,236 @@ +// RUN: %clang_cc1 -analyze -analyzer-store=region -analyzer-constraints=range -fblocks -analyzer-opt-analyze-nested-blocks -analyzer-checker=experimental.deadcode.IdempotentOperations -verify %s + +// Basic tests + +extern void test(int i); +extern void test_f(float f); + +unsigned basic() { + int x = 10, zero = 0, one = 1; + + // x op x + x = x; // expected-warning {{Assigned value is always the same as the existing value}} + test(x - x); // expected-warning {{Both operands to '-' always have the same value}} + x -= x; // expected-warning {{Both operands to '-=' always have the same value}} + x = 10; // no-warning + test(x / x); // expected-warning {{Both operands to '/' always have the same value}} + x /= x; // expected-warning {{Both operands to '/=' always have the same value}} + x = 10; // no-warning + test(x & x); // expected-warning {{Both operands to '&' always have the same value}} + x &= x; // expected-warning {{Both operands to '&=' always have the same value}} + test(x | x); // expected-warning {{Both operands to '|' always have the same value}} + x |= x; // expected-warning {{Both operands to '|=' always have the same value}} + + // x op 1 + test(x * one); // expected-warning {{The right operand to '*' is always 1}} + x *= one; // expected-warning {{The right operand to '*=' is always 1}} + test(x / one); // expected-warning {{The right operand to '/' is always 1}} + x /= one; // expected-warning {{The right operand to '/=' is always 1}} + + // 1 op x + test(one * x); // expected-warning {{The left operand to '*' is always 1}} + + // x op 0 + test(x + zero); // expected-warning {{The right operand to '+' is always 0}} + test(x - zero); // expected-warning {{The right operand to '-' is always 0}} + test(x * zero); // expected-warning {{The right operand to '*' is always 0}} + test(x & zero); // expected-warning {{The right operand to '&' is always 0}} + test(x | zero); // expected-warning {{The right operand to '|' is always 0}} + test(x ^ zero); // expected-warning {{The right operand to '^' is always 0}} + test(x << zero); // expected-warning {{The right operand to '<<' is always 0}} + test(x >> zero); // expected-warning {{The right operand to '>>' is always 0}} + + // 0 op x + test(zero + x); // expected-warning {{The left operand to '+' is always 0}} + test(zero - x); // expected-warning {{The left operand to '-' is always 0}} + test(zero / x); // expected-warning {{The left operand to '/' is always 0}} + test(zero * x); // expected-warning {{The left operand to '*' is always 0}} + test(zero & x); // expected-warning {{The left operand to '&' is always 0}} + test(zero | x); // expected-warning {{The left operand to '|' is always 0}} + test(zero ^ x); // expected-warning {{The left operand to '^' is always 0}} + test(zero << x); // expected-warning {{The left operand to '<<' is always 0}} + test(zero >> x); // expected-warning {{The left operand to '>>' is always 0}} + + // Overwrite the values so these aren't marked as Pseudoconstants + x = 1; + zero = 2; + one = 3; + + return x + zero + one; +} + +void floats(float x) { + test_f(x * 1.0); // no-warning + test_f(x * 1.0F); // no-warning +} + +// Ensure that we don't report false poitives in complex loops +void bailout() { + int unused = 0, result = 4; + result = result; // expected-warning {{Assigned value is always the same as the existing value}} + + for (unsigned bg = 0; bg < 1024; bg ++) { + result = bg * result; // no-warning + + for (int i = 0; i < 256; i++) { + unused *= i; // no-warning + } + } +} + +// Relaxed liveness - check that we don't kill liveness at assignments +typedef unsigned uintptr_t; +void kill_at_assign() { + short array[2]; + uintptr_t x = (uintptr_t) array; + short *p = (short *) x; + + // The following branch should be infeasible. + if (!(p = &array[0])) { // expected-warning{{Assigned value is always the same as the existing value}} + p = 0; + *p = 1; // no-warning + } +} + +// False positive tests + +unsigned false1() { + int a = 10; + return a * (5 - 2 - 3); // no-warning +} + +enum testenum { enum1 = 0, enum2 }; +unsigned false2() { + int a = 1234; + return enum1 + a; // no-warning +} + +// Self assignments of unused variables are common false positives +unsigned false3(int param, int param2) { + param = param; // no-warning + + // if a self assigned variable is used later, then it should be reported still + param2 = param2; // expected-warning{{Assigned value is always the same as the existing value}} + + unsigned nonparam = 5; + + nonparam = nonparam; // expected-warning{{Assigned value is always the same as the existing value}} + + return param2 + nonparam; +} + +// Pseudo-constants (vars only read) and constants should not be reported +unsigned false4() { + // Trivial constant + const int height = 1; + int c = 42; + test(height * c); // no-warning + + // Pseudo-constant (never changes after decl) + int width = height; + + return width * 10; // no-warning +} + +// Block pseudoconstants +void false4a() { + // Pseudo-constant + __block int a = 1; + int b = 10; + __block int c = 0; + b *= a; // no-warning + + ^{ + // Psuedoconstant block var + test(b * c); // no-warning + + // Non-pseudoconstant block var + int d = 0; + test(b * d); // expected-warning{{The right operand to '*' is always 0}} + d = 5; + test(d); + }(); + + test(a + b); +} + +// Static vars are common false positives +int false5() { + static int test = 0; + int a = 56; + a *= test; // no-warning + test++; + return a; +} + +// Non-local storage vars are considered false positives +int globalInt = 1; +int false6() { + int localInt = 23; + + localInt /= globalInt; + + return localInt; +} + +// Check that assignments filter out false positives correctly +int false7() { + int zero = 0; // pseudo-constant + int one = 1; + + int a = 55; + a = a; // expected-warning{{Assigned value is always the same as the existing value}} + a = enum1 * a; // no-warning + + int b = 123; + b = b; // no-warning + + return a; +} + +// Check truncations do not flag as self-assignments +void false8() { + int a = 10000000; + a = (short)a; // no-warning + test(a); +} + +// This test case previously flagged a warning at 'b == c' because the +// analyzer previously allowed 'UnknownVal' as the index for ElementRegions. +typedef struct RDar8431728_F { + int RDar8431728_A; + unsigned char *RDar8431728_B; + int RDar8431728_E[6]; +} RDar8431728_D; +static inline int RDar8431728_C(RDar8431728_D * s, int n, + unsigned char **RDar8431728_B_ptr) { + int xy, wrap, pred, a, b, c; + + xy = s->RDar8431728_E[n]; + wrap = s->RDar8431728_A; + + a = s->RDar8431728_B[xy - 1]; + b = s->RDar8431728_B[xy - 1 - wrap]; + c = s->RDar8431728_B[xy - wrap]; + + if (b == c) { // no-warning + pred = a; + } else { + pred = c; + } + + *RDar8431728_B_ptr = &s->RDar8431728_B[xy]; + + return pred; +} + +// <rdar://problem/8601243> - Don't warn on pointer arithmetic. This +// is often idiomatic. +unsigned rdar8601243_aux(unsigned n); +void rdar8601243() { + char arr[100]; + char *start = arr; + start = start + rdar8601243_aux(sizeof(arr) - (arr - start)); // no-warning + (void) start; +} + |