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.
30 lines
1.1 KiB
C++
30 lines
1.1 KiB
C++
// RUN: %clang_cc1 -std=c++1y -triple i686-pc-windows-msvc -emit-llvm %s -o - | FileCheck %s
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//CHECK: %[[A_LAMBDA:.*]] = type { %struct.A }
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//CHECK: %[[B_LAMBDA:.*]] = type { ptr }
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struct A {
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double a = 111;
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auto foo() { return [*this] { return a; }; }
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};
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namespace ns1 {
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int X = A{}.foo()();
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} //end ns1
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//CHECK: @"?foo@A@@QAE?A?<auto>@@XZ"(ptr {{[^,]*}} %this, ptr dead_on_unwind noalias writable sret(%class.anon) align 8 %[[A_LAMBDA_RETVAL:.*]])
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// get the first object with the closure type, which is of type 'struct.A'
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//CHECK: %[[I0:.+]] = getelementptr inbounds %[[A_LAMBDA]], ptr %[[A_LAMBDA_RETVAL]], i32 0, i32 0
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// copy the contents ...
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//CHECK: call void @llvm.memcpy.p0.p0.i32(ptr align 8 %[[I0]], ptr align 8 %this1, i32 8, i1 false)
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struct B {
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double b = 222;
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auto bar() { return [this] { return b; }; };
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};
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namespace ns2 {
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int X = B{}.bar()();
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}
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//CHECK: @"?bar@B@@QAE?A?<auto>@@XZ"(ptr {{[^,]*}} %this, ptr dead_on_unwind noalias writable sret(%class.anon.0) align 4 %agg.result)
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//CHECK: %[[I20:.+]] = getelementptr inbounds %class.anon.0, ptr %agg.result, i32 0, i32 0
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//CHECK: store ptr %this1, ptr %[[I20]], align 4
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