| 1 | // Test that big branch weights get scaled down to 32-bits, rather than just |
|---|
| 2 | // truncated. |
|---|
| 3 | |
|---|
| 4 | // RUN: llvm-profdata merge %S/Inputs/c-counter-overflows.proftext -o %t.profdata |
|---|
| 5 | // RUN: %clang_cc1 -triple x86_64-apple-macosx10.9 -main-file-name c-counter-overflows.c %s -o - -emit-llvm -fprofile-instrument-use-path=%t.profdata | FileCheck %s |
|---|
| 6 | |
|---|
| 7 | typedef unsigned long long uint64_t; |
|---|
| 8 | |
|---|
| 9 | int main(int argc, const char *argv[]) { |
|---|
| 10 | // Need counts higher than 32-bits. |
|---|
| 11 | // CHECK: br {{.*}} !prof ![[FOR:[0-9]+]] |
|---|
| 12 | // max = 0xffffffff0 |
|---|
| 13 | // scale = 0xffffffff0 / 0xffffffff + 1 = 17 |
|---|
| 14 | // loop-body: 0xffffffff0 / 17 + 1 = 0xf0f0f0f0 + 1 = 4042322161 => -252645135 |
|---|
| 15 | // loop-exit: 0x000000001 / 17 + 1 = 0x00000000 + 1 = 1 => 1 |
|---|
| 16 | for (uint64_t I = 0; I < 0xffffffff0; ++I) { |
|---|
| 17 | // max = 0xffffffff * 15 = 0xefffffff1 |
|---|
| 18 | // scale = 0xefffffff1 / 0xffffffff + 1 = 16 |
|---|
| 19 | // CHECK: br {{.*}} !prof ![[IF:[0-9]+]] |
|---|
| 20 | if (I & 0xf) { |
|---|
| 21 | // 0xefffffff1 / 16 + 1 = 0xefffffff + 1 = 4026531840 => -268435456 |
|---|
| 22 | } else { |
|---|
| 23 | // 0x0ffffffff / 16 + 1 = 0x0fffffff + 1 = 268435456 => 268435456 |
|---|
| 24 | } |
|---|
| 25 | |
|---|
| 26 | // max = 0xffffffff * 5 = 0x4fffffffb |
|---|
| 27 | // scale = 0x4fffffffb / 0xffffffff + 1 = 6 |
|---|
| 28 | // CHECK: ], !prof ![[SWITCH:[0-9]+]] |
|---|
| 29 | switch ((I & 0xf) / 5) { |
|---|
| 30 | case 0: |
|---|
| 31 | // 0x4fffffffb / 6 = 0xd5555554 + 1 = 3579139413 => -715827883 |
|---|
| 32 | break; |
|---|
| 33 | case 1: |
|---|
| 34 | // 0x4fffffffb / 6 = 0xd5555554 + 1 = 3579139413 => -715827883 |
|---|
| 35 | break; |
|---|
| 36 | case 2: |
|---|
| 37 | // 0x4fffffffb / 6 = 0xd5555554 + 1 = 3579139413 => -715827883 |
|---|
| 38 | break; |
|---|
| 39 | default: |
|---|
| 40 | // 0x0ffffffff / 6 = 0x2aaaaaaa + 1 = 715827883 => 715827883 |
|---|
| 41 | break; |
|---|
| 42 | } |
|---|
| 43 | } |
|---|
| 44 | return 0; |
|---|
| 45 | } |
|---|
| 46 | |
|---|
| 47 | // CHECK-DAG: ![[FOR]] = !{!"branch_weights", i32 -252645135, i32 1} |
|---|
| 48 | // CHECK-DAG: ![[IF]] = !{!"branch_weights", i32 -268435456, i32 268435456} |
|---|
| 49 | // CHECK-DAG: ![[SWITCH]] = !{!"branch_weights", i32 715827883, i32 -715827883, i32 -715827883, i32 -715827883} |
|---|
| 50 | |
|---|