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, 41 insertions, 7 deletions

diff --git a/lib/Sema/SemaStmtAsm.cpp b/lib/Sema/SemaStmtAsm.cpp
index 8c6012573c..ec8958c3c5 100644
--- a/lib/Sema/SemaStmtAsm.cpp
+++ b/lib/Sema/SemaStmtAsm.cpp
@@ -209,11 +209,12 @@ static StringRef extractRegisterName(const Expr *Expression,
 static SourceLocation
 getClobberConflictLocation(MultiExprArg Exprs, StringLiteral **Constraints,
                            StringLiteral **Clobbers, int NumClobbers,
+                           unsigned NumLabels,
                            const TargetInfo &Target, ASTContext &Cont) {
   llvm::StringSet<> InOutVars;
   // Collect all the input and output registers from the extended asm
   // statement in order to check for conflicts with the clobber list
-  for (unsigned int i = 0; i < Exprs.size(); ++i) {
+  for (unsigned int i = 0; i < Exprs.size() - NumLabels; ++i) {
     StringRef Constraint = Constraints[i]->getString();
     StringRef InOutReg = Target.getConstraintRegister(
         Constraint, extractRegisterName(Exprs[i], Target));
@@ -241,6 +242,7 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
                                  unsigned NumInputs, IdentifierInfo **Names,
                                  MultiExprArg constraints, MultiExprArg Exprs,
                                  Expr *asmString, MultiExprArg clobbers,
+                                 unsigned NumLabels,
                                  SourceLocation RParenLoc) {
   unsigned NumClobbers = clobbers.size();
   StringLiteral **Constraints =
@@ -269,7 +271,7 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
       return new (Context)
           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
-                     NumClobbers, Clobbers, RParenLoc);
+                     NumClobbers, Clobbers, NumLabels, RParenLoc);
     }
 
     ExprResult ER = CheckPlaceholderExpr(Exprs[i]);
@@ -330,7 +332,7 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
       return new (Context)
           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
-                     NumClobbers, Clobbers, RParenLoc);
+                     NumClobbers, Clobbers, NumLabels, RParenLoc);
     }
   }
 
@@ -352,7 +354,7 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
       return new (Context)
           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
-                     NumClobbers, Clobbers, RParenLoc);
+                     NumClobbers, Clobbers, NumLabels, RParenLoc);
     }
 
     ExprResult ER = CheckPlaceholderExpr(Exprs[i]);
@@ -451,14 +453,15 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
       return new (Context)
           GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
                      NumInputs, Names, Constraints, Exprs.data(), AsmString,
-                     NumClobbers, Clobbers, RParenLoc);
+                     NumClobbers, Clobbers, NumLabels, RParenLoc);
     }
   }
 
   GCCAsmStmt *NS =
     new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
                              NumInputs, Names, Constraints, Exprs.data(),
-                             AsmString, NumClobbers, Clobbers, RParenLoc);
+                             AsmString, NumClobbers, Clobbers, NumLabels,
+                             RParenLoc);
   // Validate the asm string, ensuring it makes sense given the operands we
   // have.
   SmallVector<GCCAsmStmt::AsmStringPiece, 8> Pieces;
@@ -476,8 +479,10 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
 
     // Look for the correct constraint index.
     unsigned ConstraintIdx = Piece.getOperandNo();
+    // Labels are the last in the Exprs list.
+    if (NS->isAsmGoto() && ConstraintIdx >= NS->getNumInputs())
+      continue;
     unsigned NumOperands = NS->getNumOutputs() + NS->getNumInputs();
-
     // Look for the (ConstraintIdx - NumOperands + 1)th constraint with
     // modifier '+'.
     if (ConstraintIdx >= NumOperands) {
@@ -660,10 +665,39 @@ StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
   // Check for conflicts between clobber list and input or output lists
   SourceLocation ConstraintLoc =
       getClobberConflictLocation(Exprs, Constraints, Clobbers, NumClobbers,
+                                 NumLabels,
                                  Context.getTargetInfo(), Context);
   if (ConstraintLoc.isValid())
     targetDiag(ConstraintLoc, diag::error_inoutput_conflict_with_clobber);
 
+  // Check for duplicate asm operand name between input, output and label lists.
+  typedef std::pair<StringRef , Expr *> NamedOperand;
+  SmallVector<NamedOperand, 4> NamedOperandList;
+  for (unsigned i = 0, e = NumOutputs + NumInputs + NumLabels; i != e; ++i)
+    if (Names[i])
+      NamedOperandList.emplace_back(
+          std::make_pair(Names[i]->getName(), Exprs[i]));
+  // Sort NamedOperandList.
+  std::stable_sort(NamedOperandList.begin(), NamedOperandList.end(),
+              [](const NamedOperand &LHS, const NamedOperand &RHS) {
+                return LHS.first < RHS.first;
+              });
+  // Find adjacent duplicate operand.
+  SmallVector<NamedOperand, 4>::iterator Found =
+      std::adjacent_find(begin(NamedOperandList), end(NamedOperandList),
+                         [](const NamedOperand &LHS, const NamedOperand &RHS) {
+                           return LHS.first == RHS.first;
+                         });
+  if (Found != NamedOperandList.end()) {
+    Diag((Found + 1)->second->getBeginLoc(),
+         diag::error_duplicate_asm_operand_name)
+        << (Found + 1)->first;
+    Diag(Found->second->getBeginLoc(), diag::note_duplicate_asm_operand_name)
+        << Found->first;
+    return StmtError();
+  }
+  if (NS->isAsmGoto())
+    setFunctionHasBranchIntoScope();
   return NS;
 }