[cfe-commits] r162254 - in /cfe/trunk: include/clang/AST/ASTContext.h lib/AST/ASTContext.cpp lib/CodeGen/CGExprAgg.cpp test/CodeGenObjCXX/implicit-copy-assign-operator.mm
Nico Weber
thakis at chromium.org
Fri Nov 2 15:05:02 PDT 2012
This regressed v8 garbage collection performance by 10%. Not sure if
the optimizations you're alluding to would help. I filed PR14206 for
this.
On Mon, Aug 20, 2012 at 9:10 PM, John McCall <rjmccall at apple.com> wrote:
> Author: rjmccall
> Date: Mon Aug 20 23:10:00 2012
> New Revision: 162254
>
> URL: http://llvm.org/viewvc/llvm-project?rev=162254&view=rev
> Log:
> When performing a trivial copy of a C++ type, we must be careful not
> to overwrite objects that might have been allocated into the type's
> tail padding. This patch is missing some potential optimizations where
> the destination is provably a complete object, but it's necessary for
> correctness.
>
> Patch by Jonathan Sauer.
>
> Modified:
> cfe/trunk/include/clang/AST/ASTContext.h
> cfe/trunk/lib/AST/ASTContext.cpp
> cfe/trunk/lib/CodeGen/CGExprAgg.cpp
> cfe/trunk/test/CodeGenObjCXX/implicit-copy-assign-operator.mm
>
> Modified: cfe/trunk/include/clang/AST/ASTContext.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/ASTContext.h?rev=162254&r1=162253&r2=162254&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/AST/ASTContext.h (original)
> +++ cfe/trunk/include/clang/AST/ASTContext.h Mon Aug 20 23:10:00 2012
> @@ -1427,6 +1427,10 @@
> /// characters. This method does not work on incomplete types.
> CharUnits getTypeAlignInChars(QualType T) const;
> CharUnits getTypeAlignInChars(const Type *T) const;
> +
> + // getTypeInfoDataSizeInChars - Return the size of a type, in chars. If the
> + // type is a record, its data size is returned.
> + std::pair<CharUnits, CharUnits> getTypeInfoDataSizeInChars(QualType T) const;
>
> std::pair<CharUnits, CharUnits> getTypeInfoInChars(const Type *T) const;
> std::pair<CharUnits, CharUnits> getTypeInfoInChars(QualType T) const;
>
> Modified: cfe/trunk/lib/AST/ASTContext.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ASTContext.cpp?rev=162254&r1=162253&r2=162254&view=diff
> ==============================================================================
> --- cfe/trunk/lib/AST/ASTContext.cpp (original)
> +++ cfe/trunk/lib/AST/ASTContext.cpp Mon Aug 20 23:10:00 2012
> @@ -1080,6 +1080,27 @@
> return toCharUnitsFromBits(Align);
> }
>
> +// getTypeInfoDataSizeInChars - Return the size of a type, in
> +// chars. If the type is a record, its data size is returned. This is
> +// the size of the memcpy that's performed when assigning this type
> +// using a trivial copy/move assignment operator.
> +std::pair<CharUnits, CharUnits>
> +ASTContext::getTypeInfoDataSizeInChars(QualType T) const {
> + std::pair<CharUnits, CharUnits> sizeAndAlign = getTypeInfoInChars(T);
> +
> + // In C++, objects can sometimes be allocated into the tail padding
> + // of a base-class subobject. We decide whether that's possible
> + // during class layout, so here we can just trust the layout results.
> + if (getLangOpts().CPlusPlus) {
> + if (const RecordType *RT = T->getAs<RecordType>()) {
> + const ASTRecordLayout &layout = getASTRecordLayout(RT->getDecl());
> + sizeAndAlign.first = layout.getDataSize();
> + }
> + }
> +
> + return sizeAndAlign;
> +}
> +
> std::pair<CharUnits, CharUnits>
> ASTContext::getTypeInfoInChars(const Type *T) const {
> std::pair<uint64_t, unsigned> Info = getTypeInfo(T);
>
> Modified: cfe/trunk/lib/CodeGen/CGExprAgg.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprAgg.cpp?rev=162254&r1=162253&r2=162254&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGExprAgg.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGExprAgg.cpp Mon Aug 20 23:10:00 2012
> @@ -1300,9 +1300,9 @@
> // implementation handles this case safely. If there is a libc that does not
> // safely handle this, we can add a target hook.
>
> - // Get size and alignment info for this aggregate.
> + // Get data size and alignment info for this aggregate.
> std::pair<CharUnits, CharUnits> TypeInfo =
> - getContext().getTypeInfoInChars(Ty);
> + getContext().getTypeInfoDataSizeInChars(Ty);
>
> if (alignment.isZero())
> alignment = TypeInfo.second;
>
> Modified: cfe/trunk/test/CodeGenObjCXX/implicit-copy-assign-operator.mm
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjCXX/implicit-copy-assign-operator.mm?rev=162254&r1=162253&r2=162254&view=diff
> ==============================================================================
> --- cfe/trunk/test/CodeGenObjCXX/implicit-copy-assign-operator.mm (original)
> +++ cfe/trunk/test/CodeGenObjCXX/implicit-copy-assign-operator.mm Mon Aug 20 23:10:00 2012
> @@ -1,4 +1,6 @@
> -// RUN: %clang_cc1 -fobjc-gc -emit-llvm -triple x86_64-apple-darwin10.0.0 -fobjc-runtime=macosx-fragile-10.5 -o - %s | FileCheck %s
> +// RUN: %clang_cc1 -fobjc-gc -emit-llvm -triple x86_64-apple-darwin10.0.0 -fobjc-runtime=macosx-fragile-10.5 -o - %s | FileCheck %s -check-prefix=CHECK-OBJ
> +// RUN: %clang_cc1 -x c++ -emit-llvm -triple x86_64-apple-darwin10.0.0 -o - %s | FileCheck %s -check-prefix=CHECK-CPP
> +#ifdef __OBJC__
> struct A {
> A &operator=(const A&);
> A &operator=(A&);
> @@ -41,17 +43,82 @@
> d1 = d2;
> }
>
> -// CHECK: define linkonce_odr %struct.D* @_ZN1DaSERS_
> -// CHECK: {{call.*_ZN1AaSERS_}}
> -// CHECK: {{call.*_ZN1BaSERS_}}
> -// CHECK: {{call.*_ZN1CaSERKS_}}
> -// CHECK: {{call void @llvm.memcpy.p0i8.p0i8.i64.*i64 24}}
> -// CHECK: {{call.*_ZN1BaSERS_}}
> -// CHECK: br
> -// CHECK: {{call.*_ZN1CaSERKS_}}
> -// CHECK: {{call.*@objc_memmove_collectable}}
> -// CHECK: {{call void @llvm.memcpy.p0i8.p0i8.i64.*i64 12}}
> -// CHECK: call void @_ZN11CopyByValueC1ERKS_
> -// CHECK: {{call.*_ZN11CopyByValueaSES_}}
> -// CHECK: ret
> -
> +// CHECK-OBJ: define linkonce_odr %struct.D* @_ZN1DaSERS_
> +// CHECK-OBJ: {{call.*_ZN1AaSERS_}}
> +// CHECK-OBJ: {{call.*_ZN1BaSERS_}}
> +// CHECK-OBJ: {{call.*_ZN1CaSERKS_}}
> +// CHECK-OBJ: {{call void @llvm.memcpy.p0i8.p0i8.i64.*i64 24}}
> +// CHECK-OBJ: {{call.*_ZN1BaSERS_}}
> +// CHECK-OBJ: br
> +// CHECK-OBJ: {{call.*_ZN1CaSERKS_}}
> +// CHECK-OBJ: {{call.*@objc_memmove_collectable}}
> +// CHECK-OBJ: {{call void @llvm.memcpy.p0i8.p0i8.i64.*i64 12}}
> +// CHECK-OBJ: call void @_ZN11CopyByValueC1ERKS_
> +// CHECK-OBJ: {{call.*_ZN11CopyByValueaSES_}}
> +// CHECK-OBJ: ret
> +#endif
> +
> +namespace PR13329 {
> +#ifndef __OBJC__
> + typedef void* id;
> +#endif
> + struct POD {
> + id i;
> + short s;
> + };
> +
> + struct NonPOD {
> + id i;
> + short s;
> +
> + NonPOD();
> + };
> +
> + struct DerivedNonPOD: NonPOD {
> + char c;
> + };
> +
> + struct DerivedPOD: POD {
> + char c;
> + };
> +
> + void testPOD() {
> + POD a;
> + POD b;
> + // CHECK-OBJ: @objc_memmove_collectable{{.*}}i64 16
> + // CHECK-CPP: @llvm.memcpy{{.*}}i64 16
> + b = a;
> + }
> +
> + void testNonPOD() {
> + NonPOD a;
> + NonPOD b;
> + // CHECK-OBJ: @objc_memmove_collectable{{.*}}i64 10
> + // CHECK-CPP: @llvm.memcpy{{.*}}i64 10
> + b = a;
> + }
> +
> + void testDerivedNonPOD() {
> + DerivedNonPOD a;
> + NonPOD b;
> + DerivedNonPOD c;
> + // CHECK-OBJ: @objc_memmove_collectable{{.*}}i64 10
> + // CHECK-CPP: @llvm.memcpy{{.*}}i64 10
> + (NonPOD&) a = b;
> + // CHECK-OBJ: @objc_memmove_collectable{{.*}}i64 11
> + // CHECK-CPP: @llvm.memcpy{{.*}}i64 11
> + a = c;
> + };
> +
> + void testDerivedPOD() {
> + DerivedPOD a;
> + POD b;
> + DerivedPOD c;
> + // CHECK-OBJ: @objc_memmove_collectable{{.*}}i64 16
> + // CHECK-CPP: @llvm.memcpy{{.*}}i64 16
> + (POD&) a = b;
> + // CHECK-OBJ: @objc_memmove_collectable{{.*}}i64 17
> + // CHECK-CPP: @llvm.memcpy{{.*}}i64 17
> + a = c;
> + };
> +}
>
>
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