llvm-project/clang/test/CodeGenCXX/compound-literals.cpp

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// RUN: %clang_cc1 -std=c++11 -triple armv7-none-eabi -emit-llvm -o - %s | FileCheck %s
struct X {
X();
X(const X&);
X(const char*);
~X();
};
struct Y {
int i;
X x;
};
// CHECK-LABEL: define i32 @_Z1fv()
int f() {
// CHECK: [[LVALUE:%[a-z0-9.]+]] = alloca
// CHECK-NEXT: [[I:%[a-z0-9]+]] = getelementptr inbounds {{.*}}, {{.*}}* [[LVALUE]], i32 0, i32 0
// CHECK-NEXT: store i32 17, i32* [[I]]
// CHECK-NEXT: [[X:%[a-z0-9]+]] = getelementptr inbounds {{.*}} [[LVALUE]], i32 0, i32 1
// CHECK-NEXT: call %struct.X* @_ZN1XC1EPKc({{.*}}[[X]]
// CHECK-NEXT: [[I:%[a-z0-9]+]] = getelementptr inbounds {{.*}} [[LVALUE]], i32 0, i32 0
// CHECK-NEXT: [[RESULT:%[a-z0-9]+]] = load i32, i32*
// CHECK-NEXT: call %struct.Y* @_ZN1YD1Ev
// CHECK-NEXT: ret i32 [[RESULT]]
return ((Y){17, "seventeen"}).i;
}
// CHECK-LABEL: define i32 @_Z1gv()
int g() {
// CHECK: store [2 x i32]* %{{[a-z0-9.]+}}, [2 x i32]** [[V:%[a-z0-9.]+]]
const int (&v)[2] = (int [2]) {1,2};
// CHECK: [[A:%[a-z0-9.]+]] = load [2 x i32]*, [2 x i32]** [[V]]
// CHECK-NEXT: [[A0ADDR:%[a-z0-9.]+]] = getelementptr inbounds [2 x i32], [2 x i32]* [[A]], i32 0, {{.*}} 0
// CHECK-NEXT: [[A0:%[a-z0-9.]+]] = load i32, i32* [[A0ADDR]]
// CHECK-NEXT: ret i32 [[A0]]
return v[0];
}
struct Z { int i[3]; };
int *p = (Z){ {1, 2, 3} }.i;
// CHECK: define {{.*}}__cxx_global_var_init()
// CHECK: store i32* getelementptr inbounds (%struct.Z, %struct.Z* @.compoundliteral, i32 0, i32 0, i32 0), i32** @p
int *PR21912_1 = (int []){};
// CHECK-LABEL: define {{.*}}__cxx_global_var_init.1()
// CHECK: store i32* getelementptr inbounds ([0 x i32], [0 x i32]* @.compoundliteral.2, i32 0, i32 0), i32** @PR21912_1
union PR21912Ty {
long long l;
double d;
};
union PR21912Ty *PR21912_2 = (union PR21912Ty[]){{.d = 2.0}, {.l = 3}};
// CHECK-LABEL: define {{.*}}__cxx_global_var_init.3()
// CHECK: store %union.PR21912Ty* getelementptr inbounds ([2 x %union.PR21912Ty], [2 x %union.PR21912Ty]* bitcast (<{ { double }, %union.PR21912Ty }>* @.compoundliteral.4 to [2 x %union.PR21912Ty]*), i32 0, i32 0), %union.PR21912Ty** @PR21912_2
A compound literal within a global lambda or block is still within the body of a function for the purposes of computing its storage duration and deciding whether its initializer must be constant. There are a number of problems in our current treatment of compound literals. C specifies that a compound literal yields an l-value referring to an object with either static or automatic storage duration, depending on where it was written; in the latter case, the literal object has a lifetime tied to the enclosing scope (much like an ObjC block), not the enclosing full-expression. To get these semantics fully correct in our current design, we would need to collect compound literals on the ExprWithCleanups, just like we do with ObjC blocks; we would probably also want to identify literals like we do with materialized temporaries. But it gets stranger; GCC adds compound literals to C++ as an extension, but makes them r-values, which are generally assumed to have temporary storage duration. Ignoring destructor ordering, the difference only matters if the object's address escapes the full-expression, which for an r-value can only happen with reference binding (which extends temporaries) or array-to-pointer decay (which does not). GCC then attempts to lock down on array-to-pointer decay in ad hoc ways. Arguably a far superior language solution for C++ (and perhaps even array r-values in C, which can occur in other ways) would be to propagate lifetime extension through array-to-pointer decay, so that initializing a pointer object to a decayed r-value array extends the lifetime of the complete object containing the array. But this would be a major change in semantics which arguably ought to be blessed by the committee(s). Anyway, I'm not fixing any of that in this patch; I did try, but it got out of hand. Fixes rdar://28949016. llvm-svn: 285643
2016-11-01 05:56:26 +08:00
// This compound literal should have local scope.
int computed_with_lambda = [] {
int *array = (int[]) { 1, 3, 5, 7 };
return array[0];
}();
// CHECK-LABEL: define internal i32 @{{.*}}clEv
// CHECK: alloca [4 x i32]