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[MCU] Fix assertion failure on function returning empty union. 

Treat empty struct/union in return type as void for MCU ABI. PR26438.

Differential Revision: http://reviews.llvm.org/D16808


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@260510 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Denis Zobnin 2016-02-11 11:26:03 +00:00
parent 96afe93511
commit bc350ca21c
2 changed files with 75 additions and 1 deletions
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6
lib/CodeGen/TargetInfo.cpp
View File

@ -364,7 +364,7 @@ static bool isEmptyField(ASTContext &Context, const FieldDecl *FD,
static bool isEmptyRecord(ASTContext &Context, QualType T, bool AllowArrays) {
const RecordType *RT = T->getAs<RecordType>();
if (!RT)
return 0;
return false;
const RecordDecl *RD = RT->getDecl();
if (RD->hasFlexibleArrayMember())
return false;
@ -1119,6 +1119,10 @@ ABIArgInfo X86_32ABIInfo::classifyReturnType(QualType RetTy,
if (!IsRetSmallStructInRegABI && !RetTy->isAnyComplexType())
return getIndirectReturnResult(RetTy, State);
// Ignore empty structs/unions.
if (isEmptyRecord(getContext(), RetTy, true))
return ABIArgInfo::getIgnore();
// Small structures which are register sized are generally returned
// in a register.
if (shouldReturnTypeInRegister(RetTy, getContext())) {

70
test/CodeGen/mcu-struct-return.c Normal file
View File

@ -0,0 +1,70 @@
// RUN: %clang_cc1 -triple i386-pc-elfiamcu -emit-llvm %s -o - | FileCheck %s
// Structure that is more than 8 byte.
struct Big {
double a[10];
};
// Empty union with zero size must be returned as void.
union U1 {
} u1;
// Too large union (80 bytes) must be returned via memory.
union U2 {
struct Big b;
} u2;
// Must be returned in register.
union U3 {
int x;
} u3;
// Empty struct with zero size, must be returned as void.
struct S1 {
} s1;
// Must be returend in register.
struct S2 {
int x;
} s2;
// CHECK: [[UNION1_TYPE:%.+]] = type {}
// CHECK: [[UNION2_TYPE:%.+]] = type { [[STRUCT_TYPE:%.+]] }
// CHECK: [[STRUCT_TYPE]] = type { [10 x double] }
// CHECK: [[UNION3_TYPE:%.+]] = type { i32 }
// CHECK: [[STRUCT1_TYPE:%.+]] = type {}
// CHECK: [[STRUCT2_TYPE:%.+]] = type { i32 }
union U1 foo1() { return u1; }
union U2 foo2() { return u2; }
union U3 foo3() { return u3; }
struct S1 bar1() { return s1; }
struct S2 bar2() { return s2; }
struct S1 bar3(union U1 u) { return s1; }
// CHECK: define void @foo1()
// CHECK: define void @foo2([[UNION2_TYPE]]* noalias sret %{{.+}})
// CHECK: define i32 @foo3()
// CHECK: define void @bar1()
// CHECK: define i32 @bar2()
// CHECK: define void @bar3()
void run() {
union U1 x1 = foo1();
union U2 x2 = foo2();
union U3 x3 = foo3();
struct S1 y1 = bar1();
struct S2 y2 = bar2();
struct S1 y3 = bar3(x1);
// CHECK: [[X1:%.+]] = alloca [[UNION1_TYPE]]
// CHECK: [[X2:%.+]] = alloca [[UNION2_TYPE]]
// CHECK: [[X3:%.+]] = alloca [[UNION3_TYPE]]
// CHECK: [[Y1:%.+]] = alloca [[STRUCT1_TYPE]]
// CHECK: [[Y2:%.+]] = alloca [[STRUCT2_TYPE]]
// CHECK: call void @foo1()
// CHECK: call void @foo2([[UNION2_TYPE]]* sret [[X2]])
// CHECK: {{.+}} = call i32 @foo3()
// CHECK: call void @bar1()
// CHECK: {{.+}} = call i32 @bar2()
// CHECK: call void @bar3()
}