Bruno Cardoso Lopes 6bf5b2b094 [AsmPrinter] Access pointers to globals via pcrel GOT entries ... Front-ends could use global unnamed_addr to hold pointers to other symbols, like @gotequivalent below: @foo = global i32 42 @gotequivalent = private unnamed_addr constant i32* @foo @delta = global i32 trunc (i64 sub (i64 ptrtoint (i32** @gotequivalent to i64), i64 ptrtoint (i32* @delta to i64)) to i32) The global @delta holds a data "PC"-relative offset to @gotequivalent, an unnamed pointer to @foo. The darwin/x86-64 assembly output for this follows: .globl _foo _foo: .long 42 .globl _gotequivalent _gotequivalent: .quad _foo .globl _delta _delta: .long _gotequivalent-_delta Since unnamed_addr indicates that the address is not significant, only the content, we can optimize the case above by replacing pc-relative accesses to "GOT equivalent" globals, by a PC relative access to the GOT entry of the final symbol instead. Therefore, "delta" can contain a pc relative relocation to foo's GOT entry and we avoid the emission of "gotequivalent", yielding the assembly code below: .globl _foo _foo: .long 42 .globl _delta _delta: .long _foo@GOTPCREL+4 There are a couple of advantages of doing this: (1) Front-ends that need to emit a great deal of data to store pointers to external symbols could save space by not emitting such "got equivalent" globals and (2) IR constructs combined with this opt opens a way to represent GOT pcrel relocations by using the LLVM IR, which is something we previously had no way to express. Differential Revision: http://reviews.llvm.org/D6922 rdar://problem/18534217 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230264 91177308-0d34-0410-b5e6-96231b3b80d8		2015-02-23 21:26:18 +00:00
..
Analysis	[LoopAccesses] Add -analyze support	2015-02-19 19:15:19 +00:00
Assembler	AsmParser: Check ConstantExpr insertvalue operands for type correctness	2015-02-23 07:13:52 +00:00
Bindings	[OCaml] Add Llvm.build_empty_phi.	2015-02-06 13:42:03 +00:00
Bitcode	Use common parse routine to read alignment values from bitcode	2015-02-22 19:32:03 +00:00
BugPoint
CodeGen	[X86][MMX] Fix test to reflect current codegen	2015-02-23 20:57:46 +00:00
DebugInfo	[llvm-pdbdump] Add an option to dump full class definitions.	2015-02-23 05:58:34 +00:00
ExecutionEngine	Make frem.ll flush after calling printf.	2015-02-18 19:32:28 +00:00
Feature	Don't promote asynch EH invokes of nounwind functions to calls	2015-02-11 01:23:16 +00:00
FileCheck
Instrumentation	[sanitizer] fix a test broken by r229940	2015-02-20 02:12:25 +00:00
Integer
JitListener
Linker	Add run line that was missing in r228999.	2015-02-13 16:00:03 +00:00
LTO	Introduce Target::createNullTargetStreamer and use it from IRObjectFile.	2015-02-19 00:45:02 +00:00
MC	[AsmPrinter] Access pointers to globals via pcrel GOT entries	2015-02-23 21:26:18 +00:00
Object	[obj2yaml/yaml2obj] Add SHT_GROUP support.	2015-02-21 04:28:26 +00:00
Other	Don't promote asynch EH invokes of nounwind functions to calls	2015-02-11 01:23:16 +00:00
SymbolRewriter
TableGen
tools	InstrProf: Teach llvm-cov to show the max count instead of the last	2015-02-23 21:21:34 +00:00
Transforms	Prevent hoisting fmul from THEN/ELSE to IF if there is fmsub/fmadd opportunity.	2015-02-23 19:15:16 +00:00
Unit
Verifier	Verifier: Unused comdats might not have a corresponding GV	2015-02-20 19:58:48 +00:00
YAMLParser
.clang-format
CMakeLists.txt	Back out two accidental changes that snuck in with r229245. Sorry these	2015-02-14 09:05:58 +00:00
lit.cfg	[gold] Consolidate the gold plugin options and actually search for	2015-02-14 09:43:57 +00:00
lit.site.cfg.in	Remove log statements from config scripts.	2015-02-22 07:31:42 +00:00
Makefile	Attempt to fix the builders.	2015-02-22 07:01:41 +00:00
Makefile.tests
TestRunner.sh