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

2 files changed, 11 insertions, 0 deletions

diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 4d879b46e1a..52aa3d961d2 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -370,12 +370,14 @@ void ASTStmtReader::VisitAsmStmt(AsmStmt *S) {
 
 void ASTStmtReader::VisitGCCAsmStmt(GCCAsmStmt *S) {
   VisitAsmStmt(S);
+  S->NumLabels = Record.readInt();
   S->setRParenLoc(ReadSourceLocation());
   S->setAsmString(cast_or_null<StringLiteral>(Record.readSubStmt()));
 
   unsigned NumOutputs = S->getNumOutputs();
   unsigned NumInputs = S->getNumInputs();
   unsigned NumClobbers = S->getNumClobbers();
+  unsigned NumLabels = S->getNumLabels();
 
   // Outputs and inputs
   SmallVector<IdentifierInfo *, 16> Names;
@@ -392,9 +394,14 @@ void ASTStmtReader::VisitGCCAsmStmt(GCCAsmStmt *S) {
   for (unsigned I = 0; I != NumClobbers; ++I)
     Clobbers.push_back(cast_or_null<StringLiteral>(Record.readSubStmt()));
 
+  // Labels
+  for (unsigned I = 0, N = NumLabels; I != N; ++I)
+    Exprs.push_back(Record.readSubStmt());
+
   S->setOutputsAndInputsAndClobbers(Record.getContext(),
                                     Names.data(), Constraints.data(),
                                     Exprs.data(), NumOutputs, NumInputs,
+                                    NumLabels,
                                     Clobbers.data(), NumClobbers);
 }
 
diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index b0a35cf2f56..776aab6bf51 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -283,6 +283,7 @@ void ASTStmtWriter::VisitAsmStmt(AsmStmt *S) {
 
 void ASTStmtWriter::VisitGCCAsmStmt(GCCAsmStmt *S) {
   VisitAsmStmt(S);
+  Record.push_back(S->getNumLabels());
   Record.AddSourceLocation(S->getRParenLoc());
   Record.AddStmt(S->getAsmString());
 
@@ -304,6 +305,9 @@ void ASTStmtWriter::VisitGCCAsmStmt(GCCAsmStmt *S) {
   for (unsigned I = 0, N = S->getNumClobbers(); I != N; ++I)
     Record.AddStmt(S->getClobberStringLiteral(I));
 
+  // Labels
+  for (auto *E : S->labels()) Record.AddStmt(E);
+
   Code = serialization::STMT_GCCASM;
 }