[cfe-commits] r164917 - in /cfe/trunk: lib/CodeGen/CGExprAgg.cpp lib/CodeGen/CGExprCXX.cpp lib/CodeGen/CodeGenFunction.h test/CodeGenCXX/assign-construct-memcpy.cpp
Benjamin Kramer
benny.kra at googlemail.com
Sun Sep 30 05:43:38 PDT 2012
Author: d0k
Date: Sun Sep 30 07:43:37 2012
New Revision: 164917
URL: http://llvm.org/viewvc/llvm-project?rev=164917&view=rev
Log:
CodeGen: Copy tail padding when we're not dealing with a trivial copy assign or move assign operator.
This fixes a regression from r162254, the optimizer has problems reasoning
about the smaller memcpy as it's often not safe to widen a store but making it
smaller is.
Added:
cfe/trunk/test/CodeGenCXX/assign-construct-memcpy.cpp
Modified:
cfe/trunk/lib/CodeGen/CGExprAgg.cpp
cfe/trunk/lib/CodeGen/CGExprCXX.cpp
cfe/trunk/lib/CodeGen/CodeGenFunction.h
Modified: cfe/trunk/lib/CodeGen/CGExprAgg.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprAgg.cpp?rev=164917&r1=164916&r2=164917&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprAgg.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprAgg.cpp Sun Sep 30 07:43:37 2012
@@ -1274,7 +1274,8 @@
void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
llvm::Value *SrcPtr, QualType Ty,
bool isVolatile,
- CharUnits alignment) {
+ CharUnits alignment,
+ bool isAssignment) {
assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
if (getContext().getLangOpts().CPlusPlus) {
@@ -1303,9 +1304,13 @@
// implementation handles this case safely. If there is a libc that does not
// safely handle this, we can add a target hook.
- // Get data size and alignment info for this aggregate.
- std::pair<CharUnits, CharUnits> TypeInfo =
- getContext().getTypeInfoDataSizeInChars(Ty);
+ // Get data size and alignment info for this aggregate. If this is an
+ // assignment don't copy the tail padding. Otherwise copying it is fine.
+ std::pair<CharUnits, CharUnits> TypeInfo;
+ if (isAssignment)
+ TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty);
+ else
+ TypeInfo = getContext().getTypeInfoInChars(Ty);
if (alignment.isZero())
alignment = TypeInfo.second;
Modified: cfe/trunk/lib/CodeGen/CGExprCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprCXX.cpp?rev=164917&r1=164916&r2=164917&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprCXX.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprCXX.cpp Sun Sep 30 07:43:37 2012
@@ -241,7 +241,7 @@
// We don't like to generate the trivial copy/move assignment operator
// when it isn't necessary; just produce the proper effect here.
llvm::Value *RHS = EmitLValue(*CE->arg_begin()).getAddress();
- EmitAggregateCopy(This, RHS, CE->getType());
+ EmitAggregateAssign(This, RHS, CE->getType());
return RValue::get(This);
}
@@ -378,7 +378,7 @@
MD->isTrivial()) {
llvm::Value *Src = EmitLValue(E->getArg(1)).getAddress();
QualType Ty = E->getType();
- EmitAggregateCopy(This, Src, Ty);
+ EmitAggregateAssign(This, Src, Ty);
return RValue::get(This);
}
Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=164917&r1=164916&r2=164917&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Sun Sep 30 07:43:37 2012
@@ -1653,13 +1653,26 @@
void EmitExprAsInit(const Expr *init, const ValueDecl *D,
LValue lvalue, bool capturedByInit);
+ /// EmitAggregateCopy - Emit an aggrate assignment.
+ ///
+ /// The difference to EmitAggregateCopy is that tail padding is not copied.
+ /// This is required for correctness when assigning non-POD structures in C++.
+ void EmitAggregateAssign(llvm::Value *DestPtr, llvm::Value *SrcPtr,
+ QualType EltTy, bool isVolatile=false,
+ CharUnits Alignment = CharUnits::Zero()) {
+ EmitAggregateCopy(DestPtr, SrcPtr, EltTy, isVolatile, Alignment, true);
+ }
+
/// EmitAggregateCopy - Emit an aggrate copy.
///
/// \param isVolatile - True iff either the source or the destination is
/// volatile.
+ /// \param isAssignment - If false, allow padding to be copied. This often
+ /// yields more efficient.
void EmitAggregateCopy(llvm::Value *DestPtr, llvm::Value *SrcPtr,
QualType EltTy, bool isVolatile=false,
- CharUnits Alignment = CharUnits::Zero());
+ CharUnits Alignment = CharUnits::Zero(),
+ bool isAssignment = false);
/// StartBlock - Start new block named N. If insert block is a dummy block
/// then reuse it.
Added: cfe/trunk/test/CodeGenCXX/assign-construct-memcpy.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/assign-construct-memcpy.cpp?rev=164917&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCXX/assign-construct-memcpy.cpp (added)
+++ cfe/trunk/test/CodeGenCXX/assign-construct-memcpy.cpp Sun Sep 30 07:43:37 2012
@@ -0,0 +1,89 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin12 -emit-llvm -o - -std=c++11 %s -DPOD | FileCheck %s -check-prefix=CHECK-POD
+// RUN: %clang_cc1 -triple x86_64-apple-darwin12 -emit-llvm -o - -std=c++11 %s | FileCheck %s -check-prefix=CHECK-NONPOD
+
+// Declare the reserved placement operators.
+typedef __typeof__(sizeof(0)) size_t;
+void *operator new(size_t, void*) throw();
+void operator delete(void*, void*) throw();
+void *operator new[](size_t, void*) throw();
+void operator delete[](void*, void*) throw();
+template<typename T> T &&move(T&);
+
+struct foo {
+#ifndef POD
+ foo() {} // non-POD
+#endif
+ void *a, *b;
+ bool c;
+};
+
+// It is not legal to copy the tail padding in all cases, but if it is it can
+// yield better codegen.
+
+foo *test1(void *f, const foo &x) {
+ return new (f) foo(x);
+// CHECK-POD: test1
+// CHECK-POD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+
+// CHECK-NONPOD: test1
+// CHECK-NONPOD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+}
+
+foo *test2(const foo &x) {
+ return new foo(x);
+// CHECK-POD: test2
+// CHECK-POD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+
+// CHECK-NONPOD: test2
+// CHECK-NONPOD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+}
+
+foo test3(const foo &x) {
+ foo f = x;
+ return f;
+// CHECK-POD: test3
+// CHECK-POD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+
+// CHECK-NONPOD: test3
+// CHECK-NONPOD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+}
+
+foo *test4(foo &&x) {
+ return new foo(x);
+// CHECK-POD: test4
+// CHECK-POD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+
+// CHECK-NONPOD: test4
+// CHECK-NONPOD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+}
+
+void test5(foo &f, const foo &x) {
+ f = x;
+// CHECK-POD: test5
+// CHECK-POD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+
+// CHECK-NONPOD: test5
+// CHECK-NONPOD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 17, i32 8
+}
+
+extern foo globtest;
+
+void test6(foo &&x) {
+ globtest = move(x);
+// CHECK-POD: test6
+// CHECK-POD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+
+// CHECK-NONPOD: test6
+// CHECK-NONPOD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 17, i32 8
+}
+
+void byval(foo f);
+
+void test7(const foo &x) {
+ byval(x);
+// CHECK-POD: test7
+// CHECK-POD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+
+// CHECK-NONPOD: test7
+// CHECK-NONPOD: call void @llvm.memcpy.p0i8.p0i8.i64({{.*}}i64 24, i32 8
+}
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