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b54294e2c9
As suggested by @efriedma in: https://reviews.llvm.org/D76096#4370369 This should speed up evaluating whether an expression is constant or not, but due to the complexity of these two different implementations, we may start getting different answers for edge cases for which we do not yet have test cases in-tree (or perhaps even performance regressions for some cases). As such, contributors have carte blanche to revert if necessary. For additional historical context about ExprConstant vs CGExprConstant, here's snippets from a private conversation on discord: ndesaulniers: why do we have clang/lib/AST/ExprConstant.cpp and clang/lib/CodeGen/CGExprConstant.cpp? Does clang constant fold during ast walking/creation AND during LLVM codegen? efriedma: originally, clang needed to handle two things: integer constant expressions (the "5" in "int x[5];"), and constant global initializers (the "5" in "int x = 5;"). pre-C++11, the two could be handled mostly separately; so we had the code for integer constants in AST/, and the code for globals in CodeGen/. C++11 constexpr sort of destroyed that separation, though. so now we do both kinds of constant evaluation on the AST, then CGExprConstant translates the result of that evaluation to LLVM IR. but we kept around some bits of the old cgexprconstant to avoid performance/memory usage regressions on large arrays. Reviewed By: efriedma Differential Revision: https://reviews.llvm.org/D151587
101 lines
4.5 KiB
C++
101 lines
4.5 KiB
C++
// RUN: %clang_cc1 -verify -triple x86_64-apple-darwin -emit-llvm -o - %s -std=c++1y | FileCheck %s
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// expected-no-diagnostics
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struct A {
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constexpr A() : n(1) {}
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~A();
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int n;
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};
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struct B : A {
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A a[3];
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constexpr B() {
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++a[0].n;
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a[1].n += 2;
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a[2].n = n + a[1].n;
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}
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};
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B b;
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// CHECK: @b ={{.*}} global {{.*}} i32 1, {{.*}} { i32 2 }, {{.*}} { i32 3 }, {{.*}} { i32 4 }
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// CHECK-NOT: _ZN1BC
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namespace ModifyStaticTemporary {
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struct A { int &&temporary; int x; };
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constexpr int f(int &r) { r *= 9; return r - 12; }
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A a = { 6, f(a.temporary) };
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// CHECK: @_ZGRN21ModifyStaticTemporary1aE_ = internal global i32 54
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// CHECK: @_ZN21ModifyStaticTemporary1aE ={{.*}} global {{.*}} ptr @_ZGRN21ModifyStaticTemporary1aE_, i32 42
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A b = { 7, ++b.temporary };
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// CHECK: @_ZGRN21ModifyStaticTemporary1bE_ = internal global i32 8
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// CHECK: @_ZN21ModifyStaticTemporary1bE ={{.*}} global {{.*}} ptr @_ZGRN21ModifyStaticTemporary1bE_, i32 8
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// Can't emit all of 'c' as a constant here, so emit the initial value of
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// 'c.temporary', not the value as modified by the partial evaluation within
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// the initialization of 'c.x'.
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A c = { 10, (++c.temporary, b.x) };
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// CHECK: @_ZN21ModifyStaticTemporary1cE ={{.*}} global {{.*}} zeroinitializer
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// CHECK: @_ZGRN21ModifyStaticTemporary1cE_ = internal global i32 10
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}
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// CHECK: @_ZGRN28VariableTemplateWithConstRef1iIvEE_ = linkonce_odr constant i32 5, align 4
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// CHECK: @_ZN28VariableTemplateWithConstRef3useE ={{.*}} constant ptr @_ZGRN28VariableTemplateWithConstRef1iIvEE_
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namespace VariableTemplateWithConstRef {
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template <typename T>
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const int &i = 5;
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const int &use = i<void>;
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}
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// CHECK: @_ZGRN34HiddenVariableTemplateWithConstRef1iIvEE_ = linkonce_odr hidden constant i32 5, align 4
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// CHECK: @_ZN34HiddenVariableTemplateWithConstRef3useE ={{.*}} constant ptr @_ZGRN34HiddenVariableTemplateWithConstRef1iIvEE_
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namespace HiddenVariableTemplateWithConstRef {
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template <typename T>
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__attribute__((visibility("hidden"))) const int &i = 5;
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const int &use = i<void>;
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}
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// CHECK: @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE1_ = linkonce_odr constant i32 1
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// CHECK: @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE0_ = linkonce_odr global {{.*}} { ptr @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE1_ }
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// CHECK: @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE3_ = linkonce_odr constant i32 2
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// CHECK: @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE2_ = linkonce_odr global {{.*}} { ptr @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE3_ }
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// CHECK: @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE5_ = linkonce_odr constant i32 3
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// CHECK: @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE4_ = linkonce_odr global {{.*}} { ptr @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE5_ }
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// CHECK: @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE7_ = linkonce_odr constant i32 4
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// CHECK: @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE6_ = linkonce_odr global {{.*}} { ptr @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE7_ }
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// CHECK: @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE_ = linkonce_odr global %"struct.VariableTemplateWithPack::S" { ptr @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE0_, ptr @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE2_, ptr @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE4_, ptr @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE6_ }
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// CHECK: @_ZN24VariableTemplateWithPack1pE ={{.*}} global {{.*}} @_ZGRN24VariableTemplateWithPack1sIJLi1ELi2ELi3ELi4EEEE_
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namespace VariableTemplateWithPack {
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struct A {
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const int &r;
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};
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struct S {
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A &&a, &&b, &&c, &&d;
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};
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template <int... N>
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S &&s = {A{N}...};
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S *p = &s<1, 2, 3, 4>;
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}
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// CHECK: @_ZGR1z_ ={{.*}} global [2 x i32] [i32 10, i32 2]
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// CHECK: @z = global { ptr, i32 } { ptr @_ZGR1z_, i32 10 }
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typedef int v[2];
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struct Z { int &&x, y; };
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Z z = { v{1,2}[0], z.x = 10 };
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// CHECK: @_ZGR2z2_ ={{.*}} global %struct.R { i64 10 }
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// @z = {{.}} global %struct.Z { ptr @_ZGR1z_, %struct.R { i64 10 } }
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struct R { mutable long x; };
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struct Z2 { const R &x, y; };
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Z2 z2 = { R{1}, z2.x.x = 10 };
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// CHECK: __cxa_atexit({{.*}} @_ZN1BD1Ev, {{.*}} @b
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// CHECK: define
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// CHECK-NOT: @_ZGRN21ModifyStaticTemporary1cE_
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// CHECK: store {{.*}} @_ZGRN21ModifyStaticTemporary1cE_, {{.*}} @_ZN21ModifyStaticTemporary1cE
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// CHECK: add
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// CHECK: store
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// CHECK: load {{.*}} @_ZN21ModifyStaticTemporary1bE
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// CHECK: store {{.*}} @_ZN21ModifyStaticTemporary1cE
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