xref: /llvm-project/clang/test/CodeGen/byval-memcpy-elim.c (revision 0f1c1be1968076d6f96f8a7bcc4a15cf195ecd97)
1 // RUN: %clang_cc1 -emit-llvm -triple x86_64-apple-darwin10 < %s | FileCheck %s
2 
3 struct Test1S {
4  long NumDecls;
5  long X;
6  long Y;
7 };
8 struct Test2S {
9  long NumDecls;
10  long X;
11 };
12 
13 // Make sure we don't generate extra memcpy for lvalues
14 void test1a(struct Test1S, struct Test2S);
15 // CHECK-LABEL: define{{.*}} void @test1(
16 // CHECK-NOT: memcpy
17 // CHECK: call void @test1a
test1(struct Test1S * A,struct Test2S * B)18 void test1(struct Test1S *A, struct Test2S *B) {
19   test1a(*A, *B);
20 }
21 
22 // The above gets tricker when the byval argument requires higher alignment
23 // than the natural alignment of the type in question.
24 
25 // Make sure we do generate a memcpy when we cannot guarantee alignment.
26 struct Test3S {
27   int a,b,c,d,e,f,g,h,i,j,k,l;
28 };
29 void test2a(struct Test3S q);
30 // CHECK-LABEL: define{{.*}} void @test2(
31 // CHECK: alloca %struct.Test3S, align 8
32 // CHECK: memcpy
33 // CHECK: call void @test2a
test2(struct Test3S * q)34 void test2(struct Test3S *q) {
35   test2a(*q);
36 }
37 
38 // But make sure we don't generate a memcpy when we can guarantee alignment.
39 void fooey(void);
40 // CHECK-LABEL: define{{.*}} void @test3(
41 // CHECK: alloca %struct.Test3S, align 8
42 // CHECK: call void @fooey
43 // CHECK-NOT: memcpy
44 // CHECK: call void @test2a
45 // CHECK-NOT: memcpy
46 // CHECK: call void @test2a
test3(struct Test3S a)47 void test3(struct Test3S a) {
48   struct Test3S b = a;
49   fooey();
50   test2a(a);
51   test2a(b);
52 }
53