Emit !callback metadata and introduce the callback attribute

  With commit r351627, LLVM gained the ability to apply (existing) IPO
  optimizations on indirections through callbacks, or transitive calls.
  The general idea is that we use an abstraction to hide the middle man
  and represent the callback call in the context of the initial caller.
  It is described in more detail in the commit message of the LLVM patch
  r351627, the llvm::AbstractCallSite class description, and the
  language reference section on callback-metadata.

  This commit enables clang to emit !callback metadata that is
  understood by LLVM. It does so in three different cases:
    1) For known broker functions declarations that are directly
       generated, e.g., __kmpc_fork_call for the OpenMP pragma parallel.
    2) For known broker functions that are identified by their name and
       source location through the builtin detection, e.g.,
       pthread_create from the POSIX thread API.
    3) For user annotated functions that carry the "callback(callee, ...)"
       attribute. The attribute has to include the name, or index, of
       the callback callee and how the passed arguments can be
       identified (as many as the callback callee has). See the callback
       attribute documentation for detailed information.

Differential Revision: https://reviews.llvm.org/D55483

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@351629 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 19 insertions, 0 deletions

diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 298a2bad56..be43194278 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -223,6 +223,15 @@ static bool attributeHasVariadicIdentifierArg(const IdentifierInfo &II) {
 #undef CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST
 }
 
+/// Determine whether the given attribute treats kw_this as an identifier.
+static bool attributeTreatsKeywordThisAsIdentifier(const IdentifierInfo &II) {
+#define CLANG_ATTR_THIS_ISA_IDENTIFIER_ARG_LIST
+  return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
+#include "clang/Parse/AttrParserStringSwitches.inc"
+           .Default(false);
+#undef CLANG_ATTR_THIS_ISA_IDENTIFIER_ARG_LIST
+}
+
 /// Determine whether the given attribute parses a type argument.
 static bool attributeIsTypeArgAttr(const IdentifierInfo &II) {
 #define CLANG_ATTR_TYPE_ARG_LIST
@@ -287,6 +296,12 @@ unsigned Parser::ParseAttributeArgsCommon(
   // Ignore the left paren location for now.
   ConsumeParen();
 
+  bool ChangeKWThisToIdent = attributeTreatsKeywordThisAsIdentifier(*AttrName);
+
+  // Interpret "kw_this" as an identifier if the attributed requests it.
+  if (ChangeKWThisToIdent && Tok.is(tok::kw_this))
+    Tok.setKind(tok::identifier);
+
   ArgsVector ArgExprs;
   if (Tok.is(tok::identifier)) {
     // If this attribute wants an 'identifier' argument, make it so.
@@ -314,6 +329,10 @@ unsigned Parser::ParseAttributeArgsCommon(
 
     // Parse the non-empty comma-separated list of expressions.
     do {
+      // Interpret "kw_this" as an identifier if the attributed requests it.
+      if (ChangeKWThisToIdent && Tok.is(tok::kw_this))
+        Tok.setKind(tok::identifier);
+
       ExprResult ArgExpr;
       if (Tok.is(tok::identifier) &&
           attributeHasVariadicIdentifierArg(*AttrName)) {