GodeGen, NFC: Add test to track emitStoresForConstant behavior

[vitalybuka]

format

[vitalybuka]

add test

[eugenis]

LGTM

clang/test/CodeGen/init-memset.c

36

Would it be useful to check the range of the memset? I.e. does it overlap with the following store or not.

[vitalybuka]

clang/test/CodeGen/init-memset.c

36

I don't change ranges to it will only complicate tests

clang/test/CodeGen/init-memset.c

+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -O0 -emit-llvm -o - %s | FileCheck %s
+
+void use(void *);
+
+void test_small() {
+  // CHECK-LABEL: define void @test_small()
+  int a[] = {1, 2, 3, 4};
+  // CHECK: call void @llvm.memcpy.{{.*}}
+  use(a);
+}
+
+void test_different() {
+  // CHECK-LABEL: define void @test_different()
+  int a[] = {1, 2, 3, 4, 5, 6, 7, 8, 9};
+  // CHECK: call void @llvm.memcpy.{{.*}}
+  use(a);
+}
+
+void test_all_zeros() {
+  // CHECK-LABEL: define void @test_all_zeros()
+  int a[16] = {};
+  // CHECK: call void @llvm.memset.{{.*}}
+  use(a);
+}
+
+void test_all_a() {
+  // CHECK-LABEL: define void @test_all_a()
+  char a[] = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
+  // CHECK: call void @llvm.memcpy.{{.*}}
+  use(a);
+}
+
+void test_most_zeros() {
+  // CHECK-LABEL: define void @test_most_zeros()
+  int a[16] = {0, 0, 1};
+  // CHECK: call void @llvm.memset.{{.*}}
+  // CHECK: store i32 1
+  use(a);
+}
+
+void test_most_a() {
+  // CHECK-LABEL: define void @test_most_a()
+  char a[] = "aaaaazaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
+  // CHECK: call void @llvm.memcpy.{{.*}}
+  use(a);
+}
+
+void test_pointers() {
+  // CHECK-LABEL: define void @test_pointers()
+  void *a[] = {&use, &use, &use, &use, &use, &use};
+  // CHECK: call void @llvm.memset.{{.*}}
+  // CHECK: store i8*
+  // CHECK: store i8*
+  // CHECK: store i8*
+  // CHECK: store i8*
+  // CHECK: store i8*
+  // CHECK: store i8*
+  use(a);
+}