[objc] Don't require null-check and don't emit memset when result is ignored for struct-returning method calls [clang part]

This fixes an issue with the emission of lifetime markers for struct-returning Obj-C msgSend calls. When the result of a struct-returning call is ignored, the temporary storage is only marked with lifetime markers in one of the two branches of the nil-receiver-check. The check is, however, not required when the result is unused. If we still need to emit the check (due to consumer arguments), let's not emit the memset to zero out the result if it's unused. This fixes a use-after-scope false positive with AddressSanitizer.

Differential Revision: https://reviews.llvm.org/D34834



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@306837 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 44 insertions, 1 deletions

diff --git a/test/CodeGenObjC/stret-1.m b/test/CodeGenObjC/stret-1.m
index a7bcdda48b..2314d5a9ec 100644
--- a/test/CodeGenObjC/stret-1.m
+++ b/test/CodeGenObjC/stret-1.m
@@ -12,11 +12,20 @@ struct stret one = {{1}};
 
 int main(int argc, const char **argv)
 {
-    [(id)(argc&~255) method];
+    struct stret s;
+    s = [(id)(argc&~255) method];
     // CHECK: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (%struct.stret*, i8*, i8*)*)(%struct.stret* sret [[T0:%[^,]+]]
     // CHECK: [[T0P:%.*]] = bitcast %struct.stret* [[T0]] to i8*
     // CHECK: call void @llvm.memset.p0i8.i64(i8* [[T0P]], i8 0, i64 400, i32 4, i1 false)
 
+    s = [Test method];
+    // CHECK: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (%struct.stret*, i8*, i8*)*)(%struct.stret* sret [[T1:%[^,]+]]
+    // CHECK-NOT: call void @llvm.memset.p0i8.i64(
+
+    [(id)(argc&~255) method];
+    // CHECK: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (%struct.stret*, i8*, i8*)*)(%struct.stret* sret [[T1:%[^,]+]]
+    // CHECK-NOT: call void @llvm.memset.p0i8.i64(
+
     [Test method];
     // CHECK: call void bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to void (%struct.stret*, i8*, i8*)*)(%struct.stret* sret [[T1:%[^,]+]]
     // CHECK-NOT: call void @llvm.memset.p0i8.i64(
diff --git a/test/CodeGenObjC/stret-lifetime.m b/test/CodeGenObjC/stret-lifetime.m
new file mode 100644
index 0000000000..d81ef34aee
--- /dev/null
+++ b/test/CodeGenObjC/stret-lifetime.m
@@ -0,0 +1,34 @@
+// RUN: %clang_cc1 -triple arm64-apple-darwin    -S -emit-llvm -o - -O2 -disable-llvm-passes %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -S -emit-llvm -o - -O2 -disable-llvm-passes %s | FileCheck %s
+// RUN: %clang_cc1 -triple arm64-apple-darwin    -fobjc-arc -S -emit-llvm -o - -O2 -disable-llvm-passes %s | FileCheck %s --check-prefixes=CHECK,ARC
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fobjc-arc -S -emit-llvm -o - -O2 -disable-llvm-passes %s | FileCheck %s --check-prefixes=CHECK,ARC
+
+struct stret { int x[100]; };
+struct stret one = {{1}};
+
+@interface Test
++(struct stret) method;
++(struct stret) methodConsuming:(id __attribute__((ns_consumed)))consumed;
+@end
+
+void foo(id o, id p) {
+  [o method];
+  // CHECK: @llvm.lifetime.start
+  // CHECK: call void bitcast {{.*}} @objc_msgSend
+  // CHECK: @llvm.lifetime.end
+  // CHECK-NOT: call void @llvm.memset
+
+  [o methodConsuming:p];
+  // ARC: [[T0:%.*]] = icmp eq i8*
+  // ARC: br i1 [[T0]]
+
+  // CHECK: @llvm.lifetime.start
+  // CHECK: call void bitcast {{.*}} @objc_msgSend
+  // CHECK: @llvm.lifetime.end
+  // ARC: br label
+
+  // ARC: call void @objc_release
+  // ARC: br label
+
+  // CHECK-NOT: call void @llvm.memset
+}