IR, X86: Understand !absolute_symbol metadata on global variables.
Summary:
Attaching !absolute_symbol to a global variable does two things:
1) Marks it as an absolute symbol reference.
2) Specifies the value range of that symbol's address.
Teach the X86 backend to allow absolute symbols to appear in place of
immediates by extending the relocImm and mov64imm32 matchers. Start using
relocImm in more places where it is legal.
As previously proposed on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2016-October/105800.html
Differential Revision: https://reviews.llvm.org/D25878
llvm-svn: 289087
diff --git a/llvm/lib/Target/X86/X86Subtarget.cpp b/llvm/lib/Target/X86/X86Subtarget.cpp
index f1c490c..727ff70 100644
--- a/llvm/lib/Target/X86/X86Subtarget.cpp
+++ b/llvm/lib/Target/X86/X86Subtarget.cpp
@@ -92,6 +92,10 @@
if (TM.getCodeModel() == CodeModel::Large)
return X86II::MO_NO_FLAG;
+ // Absolute symbols can be referenced directly.
+ if (GV && GV->isAbsoluteSymbolRef())
+ return X86II::MO_NO_FLAG;
+
if (TM.shouldAssumeDSOLocal(M, GV))
return classifyLocalReference(GV);