clang/test/Misc/loop-opt-setup.c

   1 // This tests loop unrolling and loop deletion (enabled under -O1)
   2 // RUN: %clang_cc1 -std=c11 -O1 -fno-unroll-loops -S -o - %s -emit-llvm | FileCheck %s
   3 // RUN: %clang_cc1 -std=c99 -O1 -fno-unroll-loops -S -o - %s -emit-llvm | FileCheck %s --check-prefix C99
   4
   5 extern int a[16];
   6 int b = 0;
   7 int foo(void) {
   8 #pragma unroll
   9   for (int i = 0; i < 16; ++i)
  10     a[i] = b += 2;
  11   return b;
  12 }
  13 // Check br i1 to make sure that the loop is fully unrolled
  14 // CHECK-LABEL: foo
  15 // CHECK-NOT: br i1
  16
  17 void Helper(void) {
  18   const int *nodes[5];
  19   int num_active = 5;
  20
  21   while (num_active)
  22 #pragma clang loop unroll(full)
  23     for (int i = 0; i < 5; ++i)
  24       if (nodes[i])
  25         --num_active;
  26 }
  27
  28 // Check br i1 to make sure the loop is gone, there will still be a label branch for the infinite loop.
  29 // In C99, there was no forward progress requirement, so we expect the infinite loop to still exist,
  30 // but for C11 and onwards, the infinite loop can be deleted.
  31 // CHECK-LABEL: Helper
  32 // C99: br label
  33 // C99-NOT: br i1
  34 // C99: br label
  35 // CHECK: entry:
  36 // CHECK-NOT: br i1
  37 // CHECK-NEXT: ret void