Add a new function attribute 'cold' to functions.

Other than recognizing the attribute, the patch does little else.
It changes the branch probability analyzer so that edges into
blocks postdominated by a cold function are given low weight.

Added analysis and code generation tests.  Added documentation for the
new attribute.

llvm-svn: 182638

3 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/AsmParser/LLLexer.cpp b/llvm/lib/AsmParser/LLLexer.cpp
index e7a9f2ad1e3..82d9975ca68 100644
--- a/llvm/lib/AsmParser/LLLexer.cpp
+++ b/llvm/lib/AsmParser/LLLexer.cpp
@@ -564,6 +564,7 @@ lltok::Kind LLLexer::LexIdentifier() {
 
   KEYWORD(alwaysinline);
   KEYWORD(byval);
+  KEYWORD(cold);
   KEYWORD(inlinehint);
   KEYWORD(inreg);
   KEYWORD(minsize);
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 62d8070d186..b22d251f9e9 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -909,6 +909,7 @@ bool LLParser::ParseFnAttributeValuePairs(AttrBuilder &B,
       continue;
     }
     case lltok::kw_alwaysinline:      B.addAttribute(Attribute::AlwaysInline); break;
+    case lltok::kw_cold:              B.addAttribute(Attribute::Cold); break;
     case lltok::kw_inlinehint:        B.addAttribute(Attribute::InlineHint); break;
     case lltok::kw_minsize:           B.addAttribute(Attribute::MinSize); break;
     case lltok::kw_naked:             B.addAttribute(Attribute::Naked); break;
@@ -1222,6 +1223,7 @@ bool LLParser::ParseOptionalReturnAttrs(AttrBuilder &B) {
 
     case lltok::kw_alignstack:
     case lltok::kw_alwaysinline:
+    case lltok::kw_cold:
     case lltok::kw_inlinehint:
     case lltok::kw_minsize:
     case lltok::kw_naked:
diff --git a/llvm/lib/AsmParser/LLToken.h b/llvm/lib/AsmParser/LLToken.h
index 3bf54fa1cc6..e889a2bfd0e 100644
--- a/llvm/lib/AsmParser/LLToken.h
+++ b/llvm/lib/AsmParser/LLToken.h
@@ -96,6 +96,7 @@ namespace lltok {
     kw_alwaysinline,
     kw_sanitize_address,
     kw_byval,
+    kw_cold,
     kw_inlinehint,
     kw_inreg,
     kw_minsize,