4deb75d2e8
In C, we'll wait until the end of the scope to clean up aggregate
temporaries used for returns from calls. This means in cases like:
{
// Assuming that `Bar` is large enough to warrant indirect returns
struct Bar b = {};
b = foo(&b);
b = foo(&b);
b = foo(&b);
b = foo(&b);
}
...We'll allocate space for 5 Bars on the stack (`b`, and 4
temporaries). This becomes painful in things like large switch
statements.
If cleaning up sooner is trivial, we should do it.
llvm-svn: 327229
102 lines
3.5 KiB
C
102 lines
3.5 KiB
C
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O1 -S -emit-llvm -o - %s | FileCheck %s --check-prefix=O1
|
|
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O0 -S -emit-llvm -o - %s | FileCheck %s --check-prefix=O0
|
|
//
|
|
// Ensure that we place appropriate lifetime markers around indirectly returned
|
|
// temporaries, and that the lifetime.ends appear in a timely manner.
|
|
//
|
|
// -O1 is used so lifetime markers actually get emitted.
|
|
|
|
struct S {
|
|
int ns[40];
|
|
};
|
|
|
|
struct S foo(void);
|
|
|
|
// CHECK-LABEL: define dso_local void @bar
|
|
struct S bar() {
|
|
// O0-NOT: @llvm.lifetime.start
|
|
// O0-NOT: @llvm.lifetime.end
|
|
|
|
struct S r;
|
|
// O1: call void @llvm.lifetime.start.p0i8({{[^,]*}}, i8* nonnull %[[R_TMP:[^)]+]])
|
|
|
|
// O1: call void @llvm.lifetime.start.p0i8({{[^,]*}}, i8* nonnull %[[TMP1:[^)]+]])
|
|
// O1: call void @foo
|
|
r = foo();
|
|
// O1: call void @llvm.lifetime.end.p0i8({{[^,]*}}, i8* nonnull %[[TMP1]])
|
|
|
|
// O1: call void @llvm.lifetime.start.p0i8({{[^,]*}}, i8* nonnull %[[TMP2:[^)]+]])
|
|
// O1: call void @foo
|
|
r = foo();
|
|
// O1: call void @llvm.lifetime.end.p0i8({{[^,]*}}, i8* nonnull %[[TMP2]])
|
|
|
|
// O1: call void @llvm.lifetime.start.p0i8({{[^,]*}}, i8* nonnull %[[TMP3:[^)]+]])
|
|
// O1: call void @foo
|
|
r = foo();
|
|
// O1: call void @llvm.lifetime.end.p0i8({{[^,]*}}, i8* nonnull %[[TMP3]])
|
|
|
|
// O1: call void @llvm.lifetime.end.p0i8({{[^,]*}}, i8* nonnull %[[R_TMP]])
|
|
return r;
|
|
}
|
|
|
|
struct S foo_int(int);
|
|
|
|
// Be sure that we're placing the lifetime.end so that all paths go through it.
|
|
// Since this function turns out to be large-ish, optnone to hopefully keep it
|
|
// stable.
|
|
// CHECK-LABEL: define dso_local void @baz
|
|
__attribute__((optnone))
|
|
struct S baz(int i, volatile int *j) {
|
|
// O0-NOT: @llvm.lifetime.start
|
|
// O0-NOT: @llvm.lifetime.end
|
|
|
|
struct S r;
|
|
// O1: %[[RESULT_ALLOCA:[^ ]+]] = alloca %struct.S
|
|
// O1: %[[TMP1_ALLOCA:[^ ]+]] = alloca %struct.S
|
|
// O1: %[[TMP2_ALLOCA:[^ ]+]] = alloca %struct.S
|
|
// O1: %[[P:[^ ]+]] = bitcast %struct.S* %[[RESULT_ALLOCA]] to i8*
|
|
// O1: call void @llvm.lifetime.start.p0i8({{[^,]*}}, i8* %[[P]])
|
|
// O1: br label %[[DO_BODY:.+]]
|
|
|
|
do {
|
|
// O1: [[DO_BODY]]:
|
|
// O1: %[[P:[^ ]+]] = bitcast %struct.S* %[[TMP1_ALLOCA]] to i8*
|
|
// O1: call void @llvm.lifetime.start.p0i8({{[^,]*}}, i8* %[[P]])
|
|
// O1: br i1 {{[^,]+}}, label %[[IF_THEN:[^,]+]], label %[[IF_END:[^,]+]]
|
|
//
|
|
// O1: [[IF_THEN]]:
|
|
// O1: %[[P:[^ ]+]] = bitcast %struct.S* %[[TMP1_ALLOCA]] to i8*
|
|
// O1: call void @llvm.lifetime.end.p0i8({{[^,]*}}, i8* %[[P]])
|
|
// O1: br label %[[DO_END:.*]]
|
|
//
|
|
// O1: [[IF_END]]:
|
|
// O1: call void @foo_int(%struct.S* sret %[[TMP1_ALLOCA]],
|
|
// O1: call void @llvm.memcpy
|
|
// O1: %[[P:[^ ]+]] = bitcast %struct.S* %[[TMP1_ALLOCA]] to i8*
|
|
// O1: call void @llvm.lifetime.end.p0i8({{[^,]*}}, i8* %[[P]])
|
|
// O1: %[[P:[^ ]+]] = bitcast %struct.S* %[[TMP2_ALLOCA]] to i8*
|
|
// O1: call void @llvm.lifetime.start.p0i8({{[^,]*}}, i8* %[[P]])
|
|
// O1: call void @foo_int(%struct.S* sret %[[TMP2_ALLOCA]],
|
|
// O1: call void @llvm.memcpy
|
|
// O1: %[[P:[^ ]+]] = bitcast %struct.S* %[[TMP2_ALLOCA]] to i8*
|
|
// O1: call void @llvm.lifetime.end.p0i8({{[^,]*}}, i8* %[[P]])
|
|
// O1: br label %[[DO_COND:.*]]
|
|
//
|
|
// O1: [[DO_COND]]:
|
|
// O1: br label %[[DO_BODY]]
|
|
r = foo_int(({
|
|
if (*j)
|
|
break;
|
|
i++;
|
|
}));
|
|
|
|
r = foo_int(i++);
|
|
} while (1);
|
|
|
|
// O1: [[DO_END]]:
|
|
// O1: call void @llvm.memcpy
|
|
// O1: %[[P:[^ ]+]] = bitcast %struct.S* %[[RESULT_ALLOCA]] to i8*
|
|
// O1: call void @llvm.lifetime.end.p0i8({{[^,]*}}, i8* %[[P]])
|
|
return r;
|
|
}
|