llvm-project

Commit Graph

Author	SHA1	Message	Date
David Green	be0c5b6d3c	[CodeGen] Align rtti and vtable data Previously the alignment on the newly created rtti/typeinfo data was largely not set, meaning that DataLayout::getPreferredAlignment was free to overalign it to 16 bytes. This causes unnecessary code bloat. Differential Revision: https://reviews.llvm.org/D51416 llvm-svn: 342053	2018-09-12 14:09:06 +00:00
Peter Collingbourne	2849c4e841	CodeGen: New vtable group representation: struct of vtable arrays. In a future change, this representation will allow us to use the new inrange annotation on getelementptr to allow the optimizer to split vtable groups. Differential Revision: https://reviews.llvm.org/D22296 llvm-svn: 289584	2016-12-13 20:40:39 +00:00
Benjamin Kramer	5d34a2b887	CodeGen: Use a fixed alignment for vtables. Pointer-sized alignment is sufficient as we only ever read single values from the table. Otherwise we'd bump the alignment to 16 bytes in the backend if the vtable is larger than 16 bytes. This is great for structures that are accessed with vector instructions or copied around, but that's simply not the case for vtables. Shrinks the data segment of a Release x86_64 clang by 0.3%. The wins are larger for i386 and code bases that use vtables more often than we do. This matches the behavior of GCC 5. llvm-svn: 217495	2014-09-10 12:50:59 +00:00

Author

SHA1

Message

Date

David Green

be0c5b6d3c

[CodeGen] Align rtti and vtable data

Previously the alignment on the newly created rtti/typeinfo data was largely
not set, meaning that DataLayout::getPreferredAlignment was free to overalign
it to 16 bytes. This causes unnecessary code bloat.

Differential Revision: https://reviews.llvm.org/D51416

llvm-svn: 342053

2018-09-12 14:09:06 +00:00

Peter Collingbourne

2849c4e841

CodeGen: New vtable group representation: struct of vtable arrays.

In a future change, this representation will allow us to use the new inrange
annotation on getelementptr to allow the optimizer to split vtable groups.

Differential Revision: https://reviews.llvm.org/D22296

llvm-svn: 289584

2016-12-13 20:40:39 +00:00

Benjamin Kramer

5d34a2b887

CodeGen: Use a fixed alignment for vtables.

Pointer-sized alignment is sufficient as we only ever read single values
from the table. Otherwise we'd bump the alignment to 16 bytes in the
backend if the vtable is larger than 16 bytes. This is great for
structures that are accessed with vector instructions or copied around, but
that's simply not the case for vtables.

Shrinks the data segment of a Release x86_64 clang by 0.3%. The wins are
larger for i386 and code bases that use vtables more often than we do.

This matches the behavior of GCC 5.

llvm-svn: 217495

2014-09-10 12:50:59 +00:00

3 Commits