llvm-project/clang
Benjamin Kramer 3d8aa5c77d CodeGen: Emit constant temporaries into read-only globals.
Instead of creating a copy on the stack just stash them in a private
constant global. This saves both the copying overhead and the stack
space, and gives the optimizer more room to constant fold.

This tries to make array temporaries more similar to regular arrays,
they can't use the same logic because a temporary has no VarDecl to be
bound to so we roll our own version here.

The original use case for this optimization was code like
  for (int i : {1, 2, 3, 4, 5, 6, 7, 8, 10})
    foo(i);
where without this patch (assuming that the loop is not unrolled) we
would alloca an array on the stack, copy the 10 values over and
iterate on that. With this patch we put the array in .text use it
directly. Apart from that case this helps on virtually any passing of
a constant std::initializer_list as a function argument.

Differential Revision: http://reviews.llvm.org/D8034

llvm-svn: 231508
2015-03-06 20:00:03 +00:00
..
INPUTS
bindings This reverts commit r227432, r227438 and r227448. 2015-01-29 17:22:53 +00:00
cmake/modules Make it easier to build against a pre-built Clang package with CMake 2014-11-05 23:14:59 +00:00
docs Revert "[UBSan] Split -fsanitize=shift into -fsanitize=shift-base and -fsanitize=shift-exponent." 2015-03-05 21:57:35 +00:00
examples Replace size() calls on containers with empty() calls where appropriate. NFC 2015-01-23 15:36:10 +00:00
include MS ABI: Insert copy-constructors into the CatchableType 2015-03-06 18:53:55 +00:00
lib CodeGen: Emit constant temporaries into read-only globals. 2015-03-06 20:00:03 +00:00
runtime Remove support for building sanitizers from Makefile/autoconf build on Linux. 2015-02-18 22:26:22 +00:00
test CodeGen: Emit constant temporaries into read-only globals. 2015-03-06 20:00:03 +00:00
tools Clang side change following r231392. 2015-03-05 19:15:09 +00:00
unittests Fix isOverride() for the case of a dependent typed base class. 2015-03-06 16:24:47 +00:00
utils Replace size() calls on containers with empty() calls where appropriate. NFC 2015-01-23 15:36:10 +00:00
www Add a download link to the web page (PR22764) 2015-03-06 00:13:55 +00:00
.arcconfig
.clang-format
.clang-tidy Enable display of compiler diagnostics in clang-tidy. 2014-10-29 17:28:51 +00:00
.gitignore
CMakeLists.txt clang/CMakeLists.txt: Introduce LLVM_SHLIB_OUTPUT_INTDIR also here, or plugins tests might fail. 2015-01-05 14:06:14 +00:00
CODE_OWNERS.TXT Add myself as a code owner for Microsoft C++ ABI code and general Windows support 2015-02-26 20:37:49 +00:00
INSTALL.txt
LICENSE.TXT
Makefile
ModuleInfo.txt
NOTES.txt
README.txt

README.txt

//===----------------------------------------------------------------------===//
// C Language Family Front-end
//===----------------------------------------------------------------------===//

Welcome to Clang.  This is a compiler front-end for the C family of languages
(C, C++, Objective-C, and Objective-C++) which is built as part of the LLVM
compiler infrastructure project.

Unlike many other compiler frontends, Clang is useful for a number of things
beyond just compiling code: we intend for Clang to be host to a number of
different source-level tools.  One example of this is the Clang Static Analyzer.

If you're interested in more (including how to build Clang) it is best to read
the relevant web sites.  Here are some pointers:

Information on Clang:              http://clang.llvm.org/
Building and using Clang:          http://clang.llvm.org/get_started.html
Clang Static Analyzer:             http://clang-analyzer.llvm.org/
Information on the LLVM project:   http://llvm.org/

If you have questions or comments about Clang, a great place to discuss them is
on the Clang development mailing list:
  http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev

If you find a bug in Clang, please file it in the LLVM bug tracker:
  http://llvm.org/bugs/