50 lines
1.9 KiB
C
50 lines
1.9 KiB
C
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// Test that big branch weights get scaled down to 32-bits, rather than just
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// truncated.
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// RUN: llvm-profdata merge %S/Inputs/c-counter-overflows.proftext -o %t.profdata
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// 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
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typedef unsigned long long uint64_t;
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int main(int argc, const char *argv[]) {
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// Need counts higher than 32-bits.
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// CHECK: br {{.*}} !prof ![[FOR:[0-9]+]]
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// max = 0xffffffff0
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// scale = 0xffffffff0 / 0xffffffff + 1 = 17
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// loop-body: 0xffffffff0 / 17 + 1 = 0xf0f0f0f0 + 1 = 4042322161 => -252645135
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// loop-exit: 0x000000001 / 17 + 1 = 0x00000000 + 1 = 1 => 1
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for (uint64_t I = 0; I < 0xffffffff0; ++I) {
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// max = 0xffffffff * 15 = 0xefffffff1
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// scale = 0xefffffff1 / 0xffffffff + 1 = 16
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// CHECK: br {{.*}} !prof ![[IF:[0-9]+]]
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if (I & 0xf) {
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// 0xefffffff1 / 16 + 1 = 0xefffffff + 1 = 4026531840 => -268435456
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} else {
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// 0x0ffffffff / 16 + 1 = 0x0fffffff + 1 = 268435456 => 268435456
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}
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// max = 0xffffffff * 5 = 0x4fffffffb
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// scale = 0x4fffffffb / 0xffffffff + 1 = 6
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// CHECK: ], !prof ![[SWITCH:[0-9]+]]
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switch ((I & 0xf) / 5) {
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case 0:
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// 0x4fffffffb / 6 = 0xd5555554 + 1 = 3579139413 => -715827883
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break;
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case 1:
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// 0x4fffffffb / 6 = 0xd5555554 + 1 = 3579139413 => -715827883
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break;
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case 2:
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// 0x4fffffffb / 6 = 0xd5555554 + 1 = 3579139413 => -715827883
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break;
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default:
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// 0x0ffffffff / 6 = 0x2aaaaaaa + 1 = 715827883 => 715827883
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break;
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}
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}
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return 0;
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}
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// CHECK-DAG: ![[FOR]] = !{!"branch_weights", i32 -252645135, i32 1}
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// CHECK-DAG: ![[IF]] = !{!"branch_weights", i32 -268435456, i32 268435456}
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// CHECK-DAG: ![[SWITCH]] = !{!"branch_weights", i32 715827883, i32 -715827883, i32 -715827883, i32 -715827883}
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