[cfe-commits] r76133 - in /cfe/trunk: lib/Analysis/CFG.cpp test/Analysis/dead-stores.c

[Ted Kremenek]

Awesome.  Thanks for doing this Mike!

On Jul 16, 2009, at 6:04 PM, Mike Stump <mrs at apple.com> wrote:

> Author: mrs
> Date: Thu Jul 16 20:04:31 2009
> New Revision: 76133
>
> URL: http://llvm.org/viewvc/llvm-project?rev=76133&view=rev
> Log:
> Make noreturn functions alter the CFG.
>
> Modified:
>    cfe/trunk/lib/Analysis/CFG.cpp
>    cfe/trunk/test/Analysis/dead-stores.c
>
> Modified: cfe/trunk/lib/Analysis/CFG.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/CFG.cpp?rev=76133&r1=76132&r2=76133&view=diff
>
> ===
> ===
> ===
> =====================================================================
> --- cfe/trunk/lib/Analysis/CFG.cpp (original)
> +++ cfe/trunk/lib/Analysis/CFG.cpp Thu Jul 16 20:04:31 2009
> @@ -117,9 +117,9 @@
>   CFGBlock* VisitStmt(Stmt* Statement);
>   CFGBlock* VisitSwitchStmt(SwitchStmt* Terminator);
>   CFGBlock* VisitWhileStmt(WhileStmt* W);
> -
> +
>   // FIXME: Add support for ObjC-specific control-flow structures.
> -
> +
>   // NYS == Not Yet Supported
>   CFGBlock* NYS() {
>     badCFG = true;
> @@ -280,7 +280,7 @@
> /// WalkAST - Used by addStmt to walk the subtree of a statement and
> ///   add extra blocks for ternary operators, &&, and ||.  We also
> ///   process "," and DeclStmts (which may contain nested control- 
> flow).
> -CFGBlock* CFGBuilder::WalkAST(Stmt* Terminator, bool AlwaysAddStmt  
> = false) {
> +CFGBlock* CFGBuilder::WalkAST(Stmt* Terminator, bool AlwaysAddStmt  
> = false) {
>   switch (Terminator->getStmtClass()) {
>     case Stmt::ConditionalOperatorClass: {
>       ConditionalOperator* C = cast<ConditionalOperator>(Terminator);
> @@ -478,6 +478,36 @@
>     case Stmt::ParenExprClass:
>       return WalkAST(cast<ParenExpr>(Terminator)->getSubExpr(),  
> AlwaysAddStmt);
>
> +  case Stmt::CallExprClass: {
> +    bool NoReturn = false;
> +    CallExpr *C = cast<CallExpr>(Terminator);
> +    Expr *CEE = C->getCallee()->IgnoreParenCasts();
> +    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CEE)) {
> +      // FIXME: We can follow objective-c methods and C++ member  
> functions...
> +      if (FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl 
> ())) {
> +        if (FD->hasAttr<NoReturnAttr>())
> +          NoReturn = true;
> +      }
> +    }
> +
> +    if (!NoReturn)
> +      break;
> +
> +    if (Block) {
> +      if (!FinishBlock(Block))
> +        return 0;
> +    }
> +
> +    // Create new block with no successor for the remaining pieces.
> +    Block = createBlock(false);
> +    Block->appendStmt(Terminator);
> +
> +    // Wire this to the exit block directly.
> +    Block->addSuccessor(&cfg->getExit());
> +
> +    return WalkAST_VisitChildren(Terminator);
> +  }
> +
>     default:
>       break;
>   };
> @@ -1190,7 +1220,7 @@
>       return 0;
>   }
>
> -  // Now create a new block that ends with the continue statement.
> +  // Now create a new block that ends with the break statement.
>   Block = createBlock(false);
>   Block->setTerminator(B);
>
>
> Modified: cfe/trunk/test/Analysis/dead-stores.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/dead-stores.c?rev=76133&r1=76132&r2=76133&view=diff
>
> === 
> === 
> === 
> =====================================================================
> --- cfe/trunk/test/Analysis/dead-stores.c (original)
> +++ cfe/trunk/test/Analysis/dead-stores.c Thu Jul 16 20:04:31 2009
> @@ -138,7 +138,8 @@
>
> // <rdar://problem/6506065>
> // The values of dead stores are only "consumed" in an enclosing  
> expression
> -// what that value is actually used.  In other words, don't say  
> "Although the value stored to 'x' is used...".
> +// what that value is actually used.  In other words, don't say  
> "Although the
> +// value stored to 'x' is used...".
> int f18() {
>    int x = 0; // no-warning
>    if (1)
> @@ -173,3 +174,14 @@
> #pragma unused(x)
> }
>
> +void halt() __attribute__((noreturn));
> +int f21() {
> +  int x = 4;
> +
> +  ++x; // expected-warning{{never read}}
> +  if (1) {
> +    halt();
> +    (void)x;
> +  }
> +  return 1;
> +}
>
>
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