clang support gnu asm goto.

Syntax:
  asm [volatile] goto ( AssemblerTemplate
                      :
                      : InputOperands
                      : Clobbers
                      : GotoLabels)

https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html

New llvm IR is "callbr" for inline asm goto instead "call" for inline asm
For:
asm goto("testl %0, %0; jne %l1;" :: "r"(cond)::label_true, loop);
IR:
callbr void asm sideeffect "testl $0, $0; jne ${1:l};", "r,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %0, i8* blockaddress(@foo, %label_true), i8* blockaddress(@foo, %loop)) #1
          to label %asm.fallthrough [label %label_true, label %loop], !srcloc !3

asm.fallthrough:                                

Compiler need to generate:
1> a dummy constarint 'X' for each label.
2> an unique fallthrough label for each asm goto stmt " asm.fallthrough%number".


Diagnostic 
1>	duplicate asm operand name are used in output, input and label.
2>	goto out of scope.

llvm-svn: 362045

1 files changed, 23 insertions, 6 deletions

diff --git a/clang/lib/AST/Stmt.cpp b/clang/lib/AST/Stmt.cpp
index 4796ee87f72..e9a2c58f1a1 100644
--- a/clang/lib/AST/Stmt.cpp
+++ b/clang/lib/AST/Stmt.cpp
@@ -444,6 +444,14 @@ void GCCAsmStmt::setInputExpr(unsigned i, Expr *E) {
   Exprs[i + NumOutputs] = E;
 }
 
+AddrLabelExpr *GCCAsmStmt::getLabelExpr(unsigned i) const {
+  return cast<AddrLabelExpr>(Exprs[i + NumInputs]);
+}
+
+StringRef GCCAsmStmt::getLabelName(unsigned i) const {
+  return getLabelExpr(i)->getLabel()->getName();
+}
+
 /// getInputConstraint - Return the specified input constraint.  Unlike output
 /// constraints, these can be empty.
 StringRef GCCAsmStmt::getInputConstraint(unsigned i) const {
@@ -456,13 +464,16 @@ void GCCAsmStmt::setOutputsAndInputsAndClobbers(const ASTContext &C,
                                                 Stmt **Exprs,
                                                 unsigned NumOutputs,
                                                 unsigned NumInputs,
+                                                unsigned NumLabels,
                                                 StringLiteral **Clobbers,
                                                 unsigned NumClobbers) {
   this->NumOutputs = NumOutputs;
   this->NumInputs = NumInputs;
   this->NumClobbers = NumClobbers;
+  this->NumLabels = NumLabels;
+  assert(!(NumOutputs && NumLabels) && "asm goto cannot have outputs");
 
-  unsigned NumExprs = NumOutputs + NumInputs;
+  unsigned NumExprs = NumOutputs + NumInputs + NumLabels;
 
   C.Deallocate(this->Names);
   this->Names = new (C) IdentifierInfo*[NumExprs];
@@ -497,6 +508,10 @@ int GCCAsmStmt::getNamedOperand(StringRef SymbolicName) const {
     if (getInputName(i) == SymbolicName)
       return getNumOutputs() + NumPlusOperands + i;
 
+  for (unsigned i = 0, e = getNumLabels(); i != e; ++i)
+    if (getLabelName(i) == SymbolicName)
+      return i + getNumInputs();
+
   // Not found.
   return -1;
 }
@@ -614,8 +629,8 @@ unsigned GCCAsmStmt::AnalyzeAsmString(SmallVectorImpl<AsmStringPiece>&Pieces,
       while (CurPtr != StrEnd && isDigit(*CurPtr))
         N = N*10 + ((*CurPtr++)-'0');
 
-      unsigned NumOperands =
-        getNumOutputs() + getNumPlusOperands() + getNumInputs();
+      unsigned NumOperands = getNumOutputs() + getNumPlusOperands() +
+                             getNumInputs() + getNumLabels();
       if (N >= NumOperands) {
         DiagOffs = CurPtr-StrStart-1;
         return diag::err_asm_invalid_operand_number;
@@ -728,10 +743,12 @@ GCCAsmStmt::GCCAsmStmt(const ASTContext &C, SourceLocation asmloc,
                        unsigned numinputs, IdentifierInfo **names,
                        StringLiteral **constraints, Expr **exprs,
                        StringLiteral *asmstr, unsigned numclobbers,
-                       StringLiteral **clobbers, SourceLocation rparenloc)
+                       StringLiteral **clobbers, unsigned numlabels,
+                       SourceLocation rparenloc)
     : AsmStmt(GCCAsmStmtClass, asmloc, issimple, isvolatile, numoutputs,
-              numinputs, numclobbers), RParenLoc(rparenloc), AsmStr(asmstr) {
-  unsigned NumExprs = NumOutputs + NumInputs;
+              numinputs, numclobbers),
+              RParenLoc(rparenloc), AsmStr(asmstr), NumLabels(numlabels) {
+  unsigned NumExprs = NumOutputs + NumInputs + NumLabels;
 
   Names = new (C) IdentifierInfo*[NumExprs];
   std::copy(names, names + NumExprs, Names);