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.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@362045 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 50 insertions, 1 deletions

diff --git a/include/clang/AST/Stmt.h b/include/clang/AST/Stmt.h
index 77b2173fcb..fe5d802688 100644
--- a/include/clang/AST/Stmt.h
+++ b/include/clang/AST/Stmt.h
@@ -46,6 +46,7 @@ class Attr;
 class CapturedDecl;
 class Decl;
 class Expr;
+class AddrLabelExpr;
 class LabelDecl;
 class ODRHash;
 class PrinterHelper;
@@ -2816,13 +2817,15 @@ class GCCAsmStmt : public AsmStmt {
   StringLiteral **Constraints = nullptr;
   StringLiteral **Clobbers = nullptr;
   IdentifierInfo **Names = nullptr;
+  unsigned NumLabels = 0;
 
 public:
   GCCAsmStmt(const ASTContext &C, SourceLocation asmloc, bool issimple,
              bool isvolatile, unsigned numoutputs, unsigned numinputs,
              IdentifierInfo **names, StringLiteral **constraints, Expr **exprs,
              StringLiteral *asmstr, unsigned numclobbers,
-             StringLiteral **clobbers, SourceLocation rparenloc);
+             StringLiteral **clobbers, unsigned numlabels,
+             SourceLocation rparenloc);
 
   /// Build an empty inline-assembly statement.
   explicit GCCAsmStmt(EmptyShell Empty) : AsmStmt(GCCAsmStmtClass, Empty) {}
@@ -2947,6 +2950,51 @@ public:
     return const_cast<GCCAsmStmt*>(this)->getInputExpr(i);
   }
 
+  //===--- Labels ---===//
+
+  bool isAsmGoto() const {
+    return NumLabels > 0;
+  }
+
+  unsigned getNumLabels() const {
+    return NumLabels;
+  }
+
+  IdentifierInfo *getLabelIdentifier(unsigned i) const {
+    return Names[i + NumInputs];
+  }
+
+  AddrLabelExpr *getLabelExpr(unsigned i) const;
+  StringRef getLabelName(unsigned i) const;
+  using labels_iterator = CastIterator<AddrLabelExpr>;
+  using const_labels_iterator = ConstCastIterator<AddrLabelExpr>;
+  using labels_range = llvm::iterator_range<labels_iterator>;
+  using labels_const_range = llvm::iterator_range<const_labels_iterator>;
+
+  labels_iterator begin_labels() {
+    return &Exprs[0] + NumInputs;
+  }
+
+  labels_iterator end_labels() {
+    return &Exprs[0] + NumInputs + NumLabels;
+  }
+
+  labels_range labels() {
+    return labels_range(begin_labels(), end_labels());
+  }
+
+  const_labels_iterator begin_labels() const {
+    return &Exprs[0] + NumInputs;
+  }
+
+  const_labels_iterator end_labels() const {
+    return &Exprs[0] + NumInputs + NumLabels;
+  }
+
+  labels_const_range labels() const {
+    return labels_const_range(begin_labels(), end_labels());
+  }
+
 private:
   void setOutputsAndInputsAndClobbers(const ASTContext &C,
                                       IdentifierInfo **Names,
@@ -2954,6 +3002,7 @@ private:
                                       Stmt **Exprs,
                                       unsigned NumOutputs,
                                       unsigned NumInputs,
+                                      unsigned NumLabels,
                                       StringLiteral **Clobbers,
                                       unsigned NumClobbers);