7954a0514b
Support for more precise TBAA metadata has been added a while ago (behind the -fpointer-tbaa flag). The more precise TBAA metadata allows treating accesses of different pointer types as no-alias. This helps to remove more redundant loads and stores in a number of workloads. Some highlights on the impact across llvm-test-suite's MultiSource, SPEC2006 & SPEC2017 include: * +2% more NoAlias results for memory accesses * +3% more stores removed by DSE, * +4% more loops vectorized. This closes a relatively big gap to GCC, which has been supporting disambiguating based on pointer types for a long time. (https://clang.godbolt.org/z/K7Wbhrz4q) Pointer-TBAA support for pointers to builtin types has been added in https://github.com/llvm/llvm-project/pull/76612. Support for user-defined types has been added in https://github.com/llvm/llvm-project/pull/110569. There are 2 recent PRs with bug fixes for special cases uncovered during testing: * https://github.com/llvm/llvm-project/pull/116991 * https://github.com/llvm/llvm-project/pull/116596 PR: https://github.com/llvm/llvm-project/pull/117244
64 lines
3.1 KiB
C++
64 lines
3.1 KiB
C++
// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes -no-pointer-tbaa %s -emit-llvm -o - | FileCheck %s -check-prefixes=CHECK,OLD-PATH
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// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes %s -emit-llvm -o - | FileCheck %s -check-prefixes=CHECK,OLD-PATH-POINTER
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// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes %s -no-pointer-tbaa -emit-llvm -new-struct-path-tbaa -o - | FileCheck %s -check-prefixes=CHECK,NEW-PATH
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// RUN: %clang_cc1 -triple x86_64-linux -O1 -disable-llvm-passes %s -emit-llvm -new-struct-path-tbaa -o - | FileCheck %s -check-prefixes=CHECK,NEW-PATH-POINTER
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//
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// Check that we generate correct TBAA information for reference accesses.
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struct S;
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struct B {
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S &s;
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B(S &s);
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S &get();
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};
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B::B(S &s) : s(s) {
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// CHECK-LABEL: _ZN1BC2ER1S
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// Check initialization of the reference parameter.
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// CHECK: store ptr {{.*}}, ptr %s.addr, align 8, !tbaa [[TAG_S_PTR:!.*]]
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// Check loading of the reference parameter.
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// CHECK: load ptr, ptr {{.*}}, !tbaa [[TAG_S_PTR:!.*]]
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// Check initialization of the reference member.
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// CHECK: store ptr {{.*}}, ptr {{.*}}, !tbaa [[TAG_S_PTR]]
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}
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S &B::get() {
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// CHECK-LABEL: _ZN1B3getEv
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// Check that we access the reference as a structure member.
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// CHECK: load ptr, ptr {{.*}}, !tbaa [[TAG_B_s:!.*]]
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return s;
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}
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// OLD-PATH-DAG: [[TAG_S_PTR]] = !{[[TYPE_pointer:!.*]], [[TYPE_pointer]], i64 0}
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// OLD-PATH-DAG: [[TAG_B_s]] = !{[[TYPE_B:!.*]], [[TYPE_pointer]], i64 0}
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//
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// OLD-PATH-DAG: [[TYPE_B]] = !{!"_ZTS1B", [[TYPE_pointer]], i64 0}
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// OLD-PATH-DAG: [[TYPE_pointer]] = !{!"any pointer", [[TYPE_char:!.*]], i64 0}
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// OLD-PATH-DAG: [[TYPE_char]] = !{!"omnipotent char", {{!.*}}, i64 0}
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// OLD-PATH-POINTER-DAG: [[TAG_S_PTR]] = !{[[TYPE_S_PTR:!.*]], [[TYPE_S_PTR]], i64 0}
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// OLD-PATH-POINTER-DAG: [[TAG_B_s]] = !{[[TYPE_B:!.*]], [[TYPE_S_PTR:!.*]], i64 0}
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//
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// OLD-PATH-POINTER-DAG: [[TYPE_B]] = !{!"_ZTS1B", [[TYPE_S_PTR:!.*]], i64 0}
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// OLD-PATH-POINTER-DAG: [[TYPE_pointer:!.*]] = !{!"any pointer", [[TYPE_char:!.*]], i64 0}
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// OLD-PATH-POINTER-DAG: [[TYPE_char]] = !{!"omnipotent char", {{!.*}}, i64 0}
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// OLD-PATH-POINTER-DAG: [[TYPE_S_PTR]] = !{!"p1 _ZTS1S", [[TYPE_pointer]], i64 0}
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// NEW-PATH-DAG: [[TAG_S_PTR]] = !{[[TYPE_pointer:!.*]], [[TYPE_pointer]], i64 0, i64 8}
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// NEW-PATH-DAG: [[TAG_B_s]] = !{[[TYPE_B:!.*]], [[TYPE_pointer]], i64 0, i64 8}
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//
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// NEW-PATH-DAG: [[TYPE_B]] = !{[[TYPE_char:!.*]], i64 8, !"_ZTS1B", [[TYPE_pointer]], i64 0, i64 8}
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// NEW-PATH-DAG: [[TYPE_pointer]] = !{[[TYPE_char:!.*]], i64 8, !"any pointer"}
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// NEW-PATH-DAG: [[TYPE_char]] = !{{{!.*}}, i64 1, !"omnipotent char"}
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// NEW-PATH-POINTER-DAG: [[TAG_S_PTR]] = !{[[TYPE_S_PTR:!.*]], [[TYPE_S_PTR]], i64 0, i64 8}
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// NEW-PATH-POINTER-DAG: [[TAG_B_s]] = !{[[TYPE_B:!.*]], [[TYPE_S_PTR]], i64 0, i64 8}
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//
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// NEW-PATH-POINTER-DAG: [[TYPE_B]] = !{[[TYPE_char:!.*]], i64 8, !"_ZTS1B", [[TYPE_S_PTR]], i64 0, i64 8}
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// NEW-PATH-POINTER-DAG: [[TYPE_S_PTR]] = !{[[TYPE_pointer:!.+]], i64 8, !"p1 _ZTS1S"}
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// NEW-PATH-POINTER-DAG: [[TYPE_pointer]] = !{[[TYPE_char:!.*]], i64 8, !"any pointer"}
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// NEW-PATH-POINTER-DAG: [[TYPE_char]] = !{{{!.*}}, i64 1, !"omnipotent char"}
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