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158d72d728
Set the writable and dead_on_unwind attributes for sret arguments. These indicate that the argument points to writable memory (and it's legal to introduce spurious writes to it on entry to the function) and that the argument memory will not be used if the call unwinds. This enables additional MemCpyOpt/DSE/LICM optimizations.
146 lines
3.6 KiB
C++
146 lines
3.6 KiB
C++
// RUN: %clang_cc1 -triple armv7-unknown-linux-gnueabihf %s -o - -emit-llvm -O2 | FileCheck %s
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// Stack should be reused when possible, no need to allocate two separate slots
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// if they have disjoint lifetime.
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// Sizes of objects are related to previously existed threshold of 32. In case
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// of S_large stack size is rounded to 40 bytes.
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// 32B
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struct S_small {
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int a[8];
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};
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// 36B
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struct S_large {
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int a[9];
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};
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// Helper class for lifetime scope absence testing
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struct Combiner {
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S_large a, b;
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Combiner(S_large);
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Combiner f();
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};
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extern S_small foo_small();
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extern S_large foo_large();
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extern void bar_small(S_small*);
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extern void bar_large(S_large*);
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// Prevent mangling of function names.
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extern "C" {
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void small_rvoed_unnamed_temporary_object() {
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// CHECK-LABEL: define{{.*}} void @small_rvoed_unnamed_temporary_object
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9foo_smallv
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// CHECK: call void @llvm.lifetime.end
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9foo_smallv
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// CHECK: call void @llvm.lifetime.end
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foo_small();
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foo_small();
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}
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void large_rvoed_unnamed_temporary_object() {
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// CHECK-LABEL: define{{.*}} void @large_rvoed_unnamed_temporary_object
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9foo_largev
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// CHECK: call void @llvm.lifetime.end
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9foo_largev
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// CHECK: call void @llvm.lifetime.end
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foo_large();
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foo_large();
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}
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void small_rvoed_named_temporary_object() {
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// CHECK-LABEL: define{{.*}} void @small_rvoed_named_temporary_object
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9foo_smallv
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// CHECK: call void @llvm.lifetime.end
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9foo_smallv
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// CHECK: call void @llvm.lifetime.end
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{
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S_small s = foo_small();
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}
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{
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S_small s = foo_small();
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}
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}
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void large_rvoed_named_temporary_object() {
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// CHECK-LABEL: define{{.*}} void @large_rvoed_named_temporary_object
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9foo_largev
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// CHECK: call void @llvm.lifetime.end
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9foo_largev
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// CHECK: call void @llvm.lifetime.end
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{
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S_large s = foo_large();
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}
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{
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S_large s = foo_large();
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}
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}
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void small_auto_object() {
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// CHECK-LABEL: define{{.*}} void @small_auto_object
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9bar_smallP7S_small
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// CHECK: call void @llvm.lifetime.end
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9bar_smallP7S_small
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// CHECK: call void @llvm.lifetime.end
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{
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S_small s;
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bar_small(&s);
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}
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{
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S_small s;
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bar_small(&s);
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}
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}
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void large_auto_object() {
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// CHECK-LABEL: define{{.*}} void @large_auto_object
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9bar_largeP7S_large
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// CHECK: call void @llvm.lifetime.end
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// CHECK: call void @llvm.lifetime.start
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// CHECK: call void @_Z9bar_largeP7S_large
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// CHECK: call void @llvm.lifetime.end
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{
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S_large s;
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bar_large(&s);
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}
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{
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S_large s;
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bar_large(&s);
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}
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}
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int large_combiner_test(S_large s) {
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// CHECK-LABEL: define{{.*}} i32 @large_combiner_test
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// CHECK: [[T2:%.*]] = alloca %struct.Combiner
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// CHECK: [[T1:%.*]] = alloca %struct.Combiner
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// CHECK: [[T3:%.*]] = call noundef ptr @_ZN8CombinerC1E7S_large(ptr {{[^,]*}} [[T1]], [9 x i32] %s.coerce)
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// CHECK: call void @_ZN8Combiner1fEv(ptr dead_on_unwind nonnull writable sret(%struct.Combiner) align 4 [[T2]], ptr {{[^,]*}} [[T1]])
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// CHECK: [[T5:%.*]] = load i32, ptr [[T2]]
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// CHECK: ret i32 [[T5]]
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return Combiner(s).f().a.a[0];
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}
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}
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