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9f8068420a
If a variable has an initializer, codegen tries to build its value. If
the variable is large in size, building its value requires substantial
resources. It causes strange behavior from user viewpoint: compilation
of huge zero initialized arrays like:
char data_1[2147483648u] = { 0 };
consumes enormous amount of time and memory.
With this change codegen tries to determine if variable initializer is
equivalent to zero initializer. In this case variable value is not
constructed.
This change fixes PR18978.
Differential Revision: https://reviews.llvm.org/D46241
llvm-svn: 332847
81 lines
2.9 KiB
C++
81 lines
2.9 KiB
C++
// RUN: %clang_cc1 -std=c++11 -S -emit-llvm -o - %s -triple x86_64-linux-gnu | FileCheck %s
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struct A { int a, b; int f(); };
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namespace NonAggregateCopyInAggregateInit { // PR32044
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struct A { constexpr A(int n) : x(n), y() {} int x, y; } extern a;
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// CHECK-DAG: @_ZN31NonAggregateCopyInAggregateInit1bE = global %{{.*}} { %[[A:.*]]* @_ZN31NonAggregateCopyInAggregateInit1aE }
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struct B { A &p; } b{{a}};
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// CHECK-DAG: @_ZGRN31NonAggregateCopyInAggregateInit1cE_ = internal global %[[A]] { i32 1, i32 0 }
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// CHECK-DAG: @_ZN31NonAggregateCopyInAggregateInit1cE = global %{{.*}} { %{{.*}}* @_ZGRN31NonAggregateCopyInAggregateInit1cE_ }
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struct C { A &&p; } c{{1}};
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}
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// CHECK-LABEL: define {{.*}}@_Z3fn1i(
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int fn1(int x) {
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// CHECK: %[[INITLIST:.*]] = alloca %struct.A
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// CHECK: %[[A:.*]] = getelementptr inbounds %struct.A, %struct.A* %[[INITLIST]], i32 0, i32 0
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// CHECK: store i32 %{{.*}}, i32* %[[A]], align 4
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// CHECK: %[[B:.*]] = getelementptr inbounds %struct.A, %struct.A* %[[INITLIST]], i32 0, i32 1
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// CHECK: store i32 5, i32* %[[B]], align 4
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// CHECK: call i32 @_ZN1A1fEv(%struct.A* %[[INITLIST]])
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return A{x, 5}.f();
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}
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struct B { int &r; int &f() { return r; } };
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// CHECK-LABEL: define {{.*}}@_Z3fn2Ri(
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int &fn2(int &v) {
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// CHECK: %[[INITLIST2:.*]] = alloca %struct.B, align 8
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// CHECK: %[[R:.*]] = getelementptr inbounds %struct.B, %struct.B* %[[INITLIST2:.*]], i32 0, i32 0
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// CHECK: store i32* %{{.*}}, i32** %[[R]], align 8
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// CHECK: call dereferenceable({{[0-9]+}}) i32* @_ZN1B1fEv(%struct.B* %[[INITLIST2:.*]])
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return B{v}.f();
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}
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// CHECK-LABEL: define {{.*}}@__cxx_global_var_init(
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//
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// CHECK: call {{.*}}@_ZN14NonTrivialInit1AC1Ev(
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// CHECK: getelementptr inbounds {{.*}}, i64 1
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// CHECK: br i1
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//
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// CHECK: getelementptr inbounds {{.*}}, i64 1
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// CHECK: icmp eq {{.*}}, i64 30
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// CHECK: br i1
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//
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// CHECK: call i32 @__cxa_atexit(
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namespace NonTrivialInit {
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struct A { A(); A(const A&) = delete; ~A(); };
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struct B { A a[20]; };
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// NB, this must be large enough to be worth memsetting for this test to be
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// meaningful.
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B b[30] = {};
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}
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namespace ZeroInit {
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enum { Zero, One };
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constexpr int zero() { return 0; }
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constexpr int *null() { return nullptr; }
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struct Filler {
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int x;
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Filler();
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};
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struct S1 {
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int x;
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};
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// These declarations, if implemented elementwise, require huge
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// amout of memory and compiler time.
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unsigned char data_1[1024 * 1024 * 1024 * 2u] = { 0 };
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unsigned char data_2[1024 * 1024 * 1024 * 2u] = { Zero };
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unsigned char data_3[1024][1024][1024] = {{{0}}};
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unsigned char data_4[1024 * 1024 * 1024 * 2u] = { zero() };
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int *data_5[1024 * 1024 * 512] = { nullptr };
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int *data_6[1024 * 1024 * 512] = { null() };
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struct S1 data_7[1024 * 1024 * 512] = {{0}};
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// This variable must be initialized elementwise.
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Filler data_e1[1024] = {};
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// CHECK: getelementptr inbounds {{.*}} @_ZN8ZeroInit7data_e1E
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}
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