Add 'musttail' marker to call instructions

This is similar to the 'tail' marker, except that it guarantees that
tail call optimization will occur.  It also comes with convervative IR
verification rules that ensure that tail call optimization is possible.

Reviewers: nicholas

Differential Revision: http://llvm-reviews.chandlerc.com/D3240

llvm-svn: 207143

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/lib/AsmParser/LLParser.h b/llvm/lib/AsmParser/LLParser.h
index f5c8a5a26d1..e2bf46290b3 100644
--- a/llvm/lib/AsmParser/LLParser.h
+++ b/llvm/lib/AsmParser/LLParser.h
@@ -372,6 +372,8 @@ namespace llvm {
     bool ParseFunctionBody(Function &Fn);
     bool ParseBasicBlock(PerFunctionState &PFS);
 
+    enum TailCallType { TCT_None, TCT_Tail, TCT_MustTail };
+
     // Instruction Parsing.  Each instruction parsing routine can return with a
     // normal result, an error result, or return having eaten an extra comma.
     enum InstResult { InstNormal = 0, InstError = 1, InstExtraComma = 2 };
@@ -398,7 +400,8 @@ namespace llvm {
     bool ParseShuffleVector(Instruction *&I, PerFunctionState &PFS);
     int ParsePHI(Instruction *&I, PerFunctionState &PFS);
     bool ParseLandingPad(Instruction *&I, PerFunctionState &PFS);
-    bool ParseCall(Instruction *&I, PerFunctionState &PFS, bool isTail);
+    bool ParseCall(Instruction *&I, PerFunctionState &PFS,
+                   CallInst::TailCallKind IsTail);
     int ParseAlloc(Instruction *&I, PerFunctionState &PFS);
     int ParseLoad(Instruction *&I, PerFunctionState &PFS);
     int ParseStore(Instruction *&I, PerFunctionState &PFS);