[PATCH] Pragma optimize on/off

Dario Domizioli dario.domizioli at gmail.com
Wed May 7 08:16:31 PDT 2014


Hi Aaron.
Thank you for the review. I'm attaching a new patch.


On 7 May 2014 15:10, Aaron Ballman <aaron at aaronballman.com> wrote:

>
> Style change -- else if should be on the same line as }
>

Fixed.


> --- test/SemaCXX/pragma-optimize-diagnostics.cpp (revision 0)
> > +++ test/SemaCXX/pragma-optimize-diagnostics.cpp (revision 0)
>
> This seems like it should be a parser test more than a sema test.
>

Moved to the Parser directory. Also added a few comments and changed the
diagnostic message (see below).


> +// - #pragma clang optimize on/off
> > +def err_pragma_optimize_malformed : Error<
> > +  "malformed argument to '#pragma clang optimize' - expected 'on' or
> 'off'">;
>
> Should probably be worded to use "unexpected" instead of "malformed."
> Perhaps: "unexpected argument '%0'; expected 'on' or 'off'" or
> something akin to that?
>

Adding a %0 is problematic as sometimes the error is that the argument is
missing or is not an identifier, so there's no text to display in the %0.
Rather than adding another diagnostic just for that specific case, I have
changed the error to "pragma clang optimize is malformed; it requires 'on'
or 'off'", which is very similar to an error message a couple of lines
above (the one about pragma detect_mismatch).
Is that satisfactory?


> +  /// directive if such directive has not been closed by an "on" yet. If
>
> "such directive" should be "such a directive".
>

Fixed.

Cheers,
    Dario Domizioli
    SN Systems - Sony Computer Entertainment Group
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Index: lib/Parse/ParsePragma.cpp
===================================================================
--- lib/Parse/ParsePragma.cpp	(revision 208218)
+++ lib/Parse/ParsePragma.cpp	(working copy)
@@ -131,6 +131,16 @@
                     Token &FirstToken) override;
 };
 
+/// PragmaOptimizeHandler - "\#pragma clang optimize on/off".
+struct PragmaOptimizeHandler : public PragmaHandler {
+  PragmaOptimizeHandler(Sema &S)
+    : PragmaHandler("optimize"), Actions(S) {}
+  void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
+                    Token &FirstToken) override;
+private:
+  Sema &Actions;
+};
+
 }  // end namespace
 
 void Parser::initializePragmaHandlers() {
@@ -195,6 +205,9 @@
     MSSection.reset(new PragmaMSPragma("section"));
     PP.AddPragmaHandler(MSSection.get());
   }
+
+  OptimizeHandler.reset(new PragmaOptimizeHandler(Actions));
+  PP.AddPragmaHandler("clang", OptimizeHandler.get());
 }
 
 void Parser::resetPragmaHandlers() {
@@ -249,6 +262,9 @@
 
   PP.RemovePragmaHandler("STDC", FPContractHandler.get());
   FPContractHandler.reset();
+
+  PP.RemovePragmaHandler("clang", OptimizeHandler.get());
+  OptimizeHandler.reset();
 }
 
 /// \brief Handle the annotation token produced for #pragma unused(...)
@@ -1531,3 +1547,34 @@
 
   Actions.ActOnPragmaMSComment(Kind, ArgumentString);
 }
+
+// #pragma clang optimize off
+// #pragma clang optimize on
+void PragmaOptimizeHandler::HandlePragma(Preprocessor &PP, 
+                                        PragmaIntroducerKind Introducer,
+                                        Token &FirstToken) {
+  Token Tok;
+  PP.Lex(Tok);
+  if (Tok.isNot(tok::identifier)) {
+    PP.Diag(Tok.getLocation(), diag::err_pragma_optimize_malformed);
+    return;
+  }
+  const IdentifierInfo *II = Tok.getIdentifierInfo();
+  // The only accepted values are 'on' or 'off'.
+  bool IsOn = false;
+  if (II->isStr("on")) {
+    IsOn = true;
+  } else if (!II->isStr("off")) {
+    PP.Diag(Tok.getLocation(), diag::err_pragma_optimize_malformed);
+    return;
+  }
+  PP.Lex(Tok);
+  
+  if (Tok.isNot(tok::eod)) {
+    PP.Diag(Tok.getLocation(), diag::warn_pragma_extra_tokens_at_eol)
+      << "clang optimize";
+    return;
+  }
+
+  Actions.ActOnPragmaOptimize(IsOn, FirstToken.getLocation());
+}
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp	(revision 208218)
+++ lib/Sema/SemaDecl.cpp	(working copy)
@@ -7378,6 +7378,11 @@
   // marking the function.
   AddCFAuditedAttribute(NewFD);
 
+  // If this is a function definition, check if we have to apply optnone due to
+  // a pragma.
+  if(D.isFunctionDefinition())
+    AddRangeBasedOptnone(NewFD);
+
   // If this is the first declaration of an extern C variable, update
   // the map of such variables.
   if (NewFD->isFirstDecl() && !NewFD->isInvalidDecl() &&
Index: lib/Sema/SemaAttr.cpp
===================================================================
--- lib/Sema/SemaAttr.cpp	(revision 208218)
+++ lib/Sema/SemaAttr.cpp	(working copy)
@@ -470,6 +470,34 @@
   D->addAttr(CFAuditedTransferAttr::CreateImplicit(Context, Loc));
 }
 
+void Sema::ActOnPragmaOptimize(bool On, SourceLocation PragmaLoc) {
+  if(On)
+    OptimizeOffPragmaLocation = SourceLocation();
+  else
+    OptimizeOffPragmaLocation = PragmaLoc;
+}
+
+void Sema::AddRangeBasedOptnone(FunctionDecl *FD) {
+  // In the future, check other pragmas if they're implemented (e.g. pragma
+  // optimize 0 will probably map to this functionality too).
+  if(OptimizeOffPragmaLocation.isValid())
+    AddOptnoneAttributeIfNoConflicts(FD, OptimizeOffPragmaLocation);
+}
+
+void Sema::AddOptnoneAttributeIfNoConflicts(FunctionDecl *FD, 
+                                            SourceLocation Loc) {
+  // Don't add a conflicting attribute. No diagnostic is needed.
+  if (FD->hasAttr<MinSizeAttr>() || FD->hasAttr<AlwaysInlineAttr>())
+    return;
+
+  // Add attributes only if required. Optnone requires noinline as well, but if
+  // either is already present then don't bother adding them.
+  if (!FD->hasAttr<OptimizeNoneAttr>())
+    FD->addAttr(OptimizeNoneAttr::CreateImplicit(Context, Loc));
+  if (!FD->hasAttr<NoInlineAttr>())
+    FD->addAttr(NoInlineAttr::CreateImplicit(Context, Loc));
+}
+
 typedef std::vector<std::pair<unsigned, SourceLocation> > VisStack;
 enum : unsigned { NoVisibility = ~0U };
 
Index: test/Parser/pragma-optimize-diagnostics.cpp
===================================================================
--- test/Parser/pragma-optimize-diagnostics.cpp	(revision 0)
+++ test/Parser/pragma-optimize-diagnostics.cpp	(revision 0)
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+#pragma clang optimize off
+
+#pragma clang optimize on
+
+// Extra arguments
+#pragma clang optimize on top of spaghetti  // expected-warning {{extra tokens at end of '#pragma clang optimize' - ignored}}
+
+// Wrong argument
+#pragma clang optimize something_wrong  // expected-error {{pragma clang optimize is malformed; it requires 'on' or 'off'}}
+
+// No argument
+#pragma clang optimize // expected-error {{pragma clang optimize is malformed; it requires 'on' or 'off'}}
+
+// Check that macros can be used in the pragma
+#define OFF off
+#define ON on
+#pragma clang optimize OFF
+#pragma clang optimize ON
+
Index: test/SemaCXX/pragma-optimize.cpp
===================================================================
--- test/SemaCXX/pragma-optimize.cpp	(revision 0)
+++ test/SemaCXX/pragma-optimize.cpp	(revision 0)
@@ -0,0 +1,113 @@
+// RUN: %clang_cc1 -x c++ -std=c++11 -emit-llvm -O2 < %s | FileCheck %s
+
+#pragma clang optimize off
+
+// This is a macro definition and therefore its text is not present after
+// preprocessing. The pragma has no effect here.
+#define CREATE_FUNC(name)        \
+int name (int param) {           \
+    return param;                \
+}                                \
+
+// This is a declaration and therefore it is not decorated with `optnone`.
+extern int foo(int a, int b);
+// CHECK-DAG: @_Z3fooii{{.*}} [[ATTRFOO:#[0-9]+]]
+
+// This is a definition and therefore it will be decorated with `optnone`.
+int bar(int x, int y) {
+    for(int i = 0; i < x; ++i)
+        y += x;
+    return y + foo(x, y);
+}
+// CHECK-DAG: @_Z3barii{{.*}} [[ATTRBAR:#[0-9]+]]
+
+// The function "int created (int param)" created by the macro invocation
+// is also decorated with the `optnone` attribute because it is within a
+// region of code affected by the functionality (not because of the position
+// of the macro definition).
+CREATE_FUNC (created)
+// CHECK-DAG: @_Z7createdi{{.*}} [[ATTRCREATED:#[0-9]+]]
+
+class MyClass {
+    public:
+        // The declaration of the method is not decorated with `optnone`.
+        int method(int blah);
+};
+
+// The definition of the method instead is decorated with `optnone`.
+int MyClass::method(int blah) {
+    return blah + 1;
+}
+// CHECK-DAG: @_ZN7MyClass6methodEi{{.*}} [[ATTRMETHOD:#[0-9]+]]
+
+// A template declaration will not be decorated with `optnone`.
+template <typename T> T twice (T param);
+
+// The template definition will be decorated with the attribute `optnone`.
+template <typename T> T thrice (T param) {
+    return 3 * param;
+}
+
+// This function definition will not be decorated with `optnone` because the
+// attribute would conflict with `always_inline`.
+int __attribute__((always_inline)) baz(int z) {
+    return foo(z, 2);
+}
+// CHECK-DAG: @_Z3bazi{{.*}} [[ATTRBAZ:#[0-9]+]]
+
+#pragma clang optimize on
+
+// The function "int wombat(int param)" created by the macro is not
+// decorated with `optnone`, because the pragma applies its effects only
+// after preprocessing. The position of the macro definition is not
+// relevant.
+CREATE_FUNC (wombat)
+// CHECK-DAG: @_Z6wombati{{.*}} [[ATTRWOMBAT:#[0-9]+]]
+
+// This instantiation of the "twice" template function with a "float" type
+// will not have an `optnone` attribute because the template declaration was
+// not affected by the pragma.
+float container (float par) {
+    return twice(par);
+}
+// CHECK-DAG: @_Z9containerf{{.*}} [[ATTRCONTAINER:#[0-9]+]]
+// CHECK-DAG: @_Z5twiceIfET_S0_{{.*}} [[ATTRTWICE:#[0-9]+]]
+
+// This instantiation of the "thrice" template function with a "float" type
+// will have an `optnone` attribute because the template definition was
+// affected by the pragma.
+float container2 (float par) {
+    return thrice(par);
+}
+// CHECK-DAG: @_Z10container2f{{.*}} [[ATTRCONTAINER2:#[0-9]+]]
+// CHECK-DAG: @_Z6thriceIfET_S0_{{.*}} [[ATTRTHRICEFLOAT:#[0-9]+]]
+
+
+// A template specialization is a new definition and it will not be
+// decorated with an `optnone` attribute because it is now outside of the
+// affected region.
+template<> int thrice(int par) {
+    return (par << 1) + par;
+}
+int container3 (int par) {
+    return thrice(par);
+}
+// CHECK-DAG: @_Z10container3i{{.*}} [[ATTRCONTAINER3:#[0-9]+]]
+// CHECK-DAG: @_Z6thriceIiET_S0_{{.*}} [[ATTRTHRICEINT:#[0-9]+]]
+
+
+// Check for both noinline and optnone on each function that should have them.
+// CHECK-DAG: attributes [[ATTRBAR]] = { {{.*}}noinline{{.*}}optnone{{.*}} }
+// CHECK-DAG: attributes [[ATTRCREATED]] = { {{.*}}noinline{{.*}}optnone{{.*}} }
+// CHECK-DAG: attributes [[ATTRMETHOD]] = { {{.*}}noinline{{.*}}optnone{{.*}} }
+// CHECK-DAG: attributes [[ATTRTHRICEFLOAT]] = { {{.*}}noinline{{.*}}optnone{{.*}} }
+
+// Check that the other functions do NOT have optnone.
+// CHECK-DAG-NOT: attributes [[ATTRFOO]] = { {{.*}}optnone{{.*}} }
+// CHECK-DAG-NOT: attributes [[ATTRBAZ]] = { {{.*}}optnone{{.*}} }
+// CHECK-DAG-NOT: attributes [[ATTRWOMBAT]] = { {{.*}}optnone{{.*}} }
+// CHECK-DAG-NOT: attributes [[ATTRCONTAINER]] = { {{.*}}optnone{{.*}} }
+// CHECK-DAG-NOT: attributes [[ATTRTWICE]] = { {{.*}}optnone{{.*}} }
+// CHECK-DAG-NOT: attributes [[ATTRCONTAINER2]] = { {{.*}}optnone{{.*}} }
+// CHECK-DAG-NOT: attributes [[ATTRCONTAINER3]] = { {{.*}}optnone{{.*}} }
+// CHECK-DAG-NOT: attributes [[ATTRTHRICEINT]] = { {{.*}}optnone{{.*}} }
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h	(revision 208218)
+++ include/clang/Sema/Sema.h	(working copy)
@@ -333,6 +333,11 @@
   /// VisContext - Manages the stack for \#pragma GCC visibility.
   void *VisContext; // Really a "PragmaVisStack*"
 
+  /// \brief This represents the last location of a "#pragma clang optimize off"
+  /// directive if such a directive has not been closed by an "on" yet. If
+  /// optimizations are currently "on", this is set to an invalid location.
+  SourceLocation OptimizeOffPragmaLocation;
+
   /// \brief Flag indicating if Sema is building a recovery call expression.
   ///
   /// This flag is used to avoid building recovery call expressions
@@ -7228,6 +7233,19 @@
   /// the appropriate attribute.
   void AddCFAuditedAttribute(Decl *D);
 
+  /// \brief Called on well formed \#pragma clang optimize.
+  void ActOnPragmaOptimize(bool On, SourceLocation PragmaLoc);
+
+  /// \brief Only called on function definitions; if there is a pragma in scope
+  /// with the effect of a range-based optnone, consider marking the function
+  /// with attribute optnone.
+  void AddRangeBasedOptnone(FunctionDecl *FD);
+
+  /// \brief Adds the 'optnone' attribute to the function declaration if there
+  /// are no conflicts; Loc represents the location causing the 'optnone'
+  /// attribute to be added (usually because of a pragma).
+  void AddOptnoneAttributeIfNoConflicts(FunctionDecl *FD, SourceLocation Loc);
+
   /// AddAlignedAttr - Adds an aligned attribute to a particular declaration.
   void AddAlignedAttr(SourceRange AttrRange, Decl *D, Expr *E,
                       unsigned SpellingListIndex, bool IsPackExpansion);
Index: include/clang/Parse/Parser.h
===================================================================
--- include/clang/Parse/Parser.h	(revision 208218)
+++ include/clang/Parse/Parser.h	(working copy)
@@ -160,6 +160,7 @@
   std::unique_ptr<PragmaHandler> MSConstSeg;
   std::unique_ptr<PragmaHandler> MSCodeSeg;
   std::unique_ptr<PragmaHandler> MSSection;
+  std::unique_ptr<PragmaHandler> OptimizeHandler;
 
   std::unique_ptr<CommentHandler> CommentSemaHandler;
 
Index: include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- include/clang/Basic/DiagnosticParseKinds.td	(revision 208218)
+++ include/clang/Basic/DiagnosticParseKinds.td	(working copy)
@@ -841,6 +841,9 @@
 def err_pragma_pointers_to_members_unknown_kind : Error<
   "unexpected %0, expected to see one of %select{|'best_case', 'full_generality', }1"
   "'single_inheritance', 'multiple_inheritance', or 'virtual_inheritance'">;
+// - #pragma clang optimize on/off
+def err_pragma_optimize_malformed : Error<
+  "pragma clang optimize is malformed; it requires 'on' or 'off'">;
 
 // OpenCL Section 6.8.g
 def err_not_opencl_storage_class_specifier : Error<


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