1 // RUN: %clang -O1 -fvectorize -target x86_64-unknown-unknown -Rpass-analysis=loop-vectorize -emit-llvm -S %s -o - 2>&1 | FileCheck %s 2 3 // CHECK: {{.*}}:9:11: remark: loop not vectorized: cannot prove it is safe to reorder floating-point operations; allow reordering by specifying '#pragma clang loop vectorize(enable)' before the loop or by providing the compiler option '-ffast-math'. 4 5 double foo(int N) { 6 double v = 0.0; 7 8 for (int i = 0; i < N; i++) 9 v = v + 1.0; 10 11 return v; 12 } 13 14 // CHECK: {{.*}}:18:13: remark: loop not vectorized: cannot prove it is safe to reorder memory operations; allow reordering by specifying '#pragma clang loop vectorize(enable)' before the loop. If the arrays will always be independent specify '#pragma clang loop vectorize(assume_safety)' before the loop or provide the '__restrict__' qualifier with the independent array arguments. Erroneous results will occur if these options are incorrectly applied! 15 16 void foo2(int *dw, int *uw, int *A, int *B, int *C, int *D, int N) { 17 for (int i = 0; i < N; i++) { 18 dw[i] = A[i] + B[i - 1] + C[i - 2] + D[i - 3]; 19 uw[i] = A[i] + B[i + 1] + C[i + 2] + D[i + 3]; 20 } 21 } 22