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.
71 lines
2.1 KiB
C++
71 lines
2.1 KiB
C++
// RUN: %clang_cc1 -emit-llvm %s -o - -triple=i686-pc-win32 -mconstructor-aliases -fno-rtti | FileCheck %s
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struct A {
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A() : a(42) {}
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A(const A &o) : a(o.a) {}
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~A() {}
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int a;
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};
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struct B {
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A foo(A o);
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A __cdecl bar(A o);
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A __stdcall baz(A o);
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A __fastcall qux(A o);
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};
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A B::foo(A x) {
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return x;
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}
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// CHECK-LABEL: define dso_local x86_thiscallcc ptr @"?foo@B@@QAE?AUA@@U2@@Z"
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// CHECK: (ptr noundef %this, ptr inalloca(<{ ptr, %struct.A }>) %0)
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// CHECK: getelementptr inbounds <{ ptr, %struct.A }>, ptr %{{.*}}, i32 0, i32 0
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// CHECK: load ptr, ptr
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// CHECK: ret ptr
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A B::bar(A x) {
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return x;
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}
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// CHECK-LABEL: define dso_local ptr @"?bar@B@@QAA?AUA@@U2@@Z"
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// CHECK: (ptr inalloca(<{ ptr, ptr, %struct.A }>) %0)
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// CHECK: getelementptr inbounds <{ ptr, ptr, %struct.A }>, ptr %{{.*}}, i32 0, i32 1
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// CHECK: load ptr, ptr
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// CHECK: ret ptr
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A B::baz(A x) {
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return x;
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}
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// CHECK-LABEL: define dso_local x86_stdcallcc ptr @"?baz@B@@QAG?AUA@@U2@@Z"
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// CHECK: (ptr inalloca(<{ ptr, ptr, %struct.A }>) %0)
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// CHECK: getelementptr inbounds <{ ptr, ptr, %struct.A }>, ptr %{{.*}}, i32 0, i32 1
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// CHECK: load ptr, ptr
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// CHECK: ret ptr
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A B::qux(A x) {
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return x;
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}
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// CHECK-LABEL: define dso_local x86_fastcallcc void @"?qux@B@@QAI?AUA@@U2@@Z"
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// CHECK: (ptr inreg noundef %this, ptr dead_on_unwind inreg noalias writable sret(%struct.A) align 4 %agg.result, ptr inalloca(<{ %struct.A }>) %0)
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// CHECK: ret void
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int main() {
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B b;
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A a = b.foo(A());
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a = b.bar(a);
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a = b.baz(a);
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a = b.qux(a);
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}
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// CHECK: call x86_thiscallcc ptr @"?foo@B@@QAE?AUA@@U2@@Z"
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// CHECK: (ptr noundef %{{[^,]*}}, ptr inalloca(<{ ptr, %struct.A }>) %{{[^,]*}})
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// CHECK: call ptr @"?bar@B@@QAA?AUA@@U2@@Z"
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// CHECK: (ptr inalloca(<{ ptr, ptr, %struct.A }>) %{{[^,]*}})
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// CHECK: call x86_stdcallcc ptr @"?baz@B@@QAG?AUA@@U2@@Z"
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// CHECK: (ptr inalloca(<{ ptr, ptr, %struct.A }>) %{{[^,]*}})
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// CHECK: call x86_fastcallcc void @"?qux@B@@QAI?AUA@@U2@@Z"
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// CHECK: (ptr inreg noundef %{{[^,]*}}, ptr dead_on_unwind inreg writable sret(%struct.A) align 4 %{{.*}}, ptr inalloca(<{ %struct.A }>) %{{[^,]*}})
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