clang/test/CodeGen/byval-memcpy-elim.c

   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
  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
  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
  47 void test3(struct Test3S a) {
  48   struct Test3S b = a;
  49   fooey();
  50   test2a(a);
  51   test2a(b);
  52 }