[PATCH] D12134: Improve debug info for implicitly captured vars in lambdas

[David Blaikie via cfe-commits]

On Tue, Aug 25, 2015 at 8:18 AM, Bataev, Alexey <a.bataev at hotmail.com>
wrote:

> I though about this. I think it will be more convenient for user to see
> the diagnostic on the first use of the variable rather than on '=' or '&'
> symbol.
>

Why the difference between the diagnostic & the debug info, then?


>
> Best regards,
> Alexey Bataev
> =============
> Software Engineer
> Intel Compiler Team
>
> 25.08.2015 18:07, David Blaikie пишет:
>
>>
>>
>> On Tue, Aug 18, 2015 at 9:05 PM, Alexey Bataev via cfe-commits <
>> cfe-commits at lists.llvm.org <mailto:cfe-commits at lists.llvm.org>> wrote:
>>
>>     ABataev created this revision.
>>     ABataev added reviewers: echristo, rjmccall, rsmith.
>>     ABataev added a subscriber: cfe-commits.
>>
>>     When variables are implicitly captured in lambdas, debug info
>>     generated for captured variables points to location where they are
>>     used first.  This patch makes debug info to point to capture
>>     default location.
>>
>>
>> Not sure if this is the right tradeoff, or if it is, perhaps we should
>> reconsider how our diagnostics work too?
>>
>> Currently if you, say, capture a variable by value and that variable
>> doesn't have an accessible copy ctor, the diagnostic points to the first
>> use. Should we change that too?
>>
>>
>>     http://reviews.llvm.org/D12134
>>
>>     Files:
>>       lib/Sema/SemaLambda.cpp
>>       test/CodeGenCXX/debug-lambda-expressions.cpp
>>
>>     Index: lib/Sema/SemaLambda.cpp
>>     ===================================================================
>>     --- lib/Sema/SemaLambda.cpp
>>     +++ lib/Sema/SemaLambda.cpp
>>     @@ -1377,10 +1377,10 @@
>>      }
>>
>>      static ExprResult performLambdaVarCaptureInitialization(
>>     -    Sema &S, LambdaScopeInfo::Capture &Capture,
>>     -    FieldDecl *Field,
>>     +    Sema &S, LambdaScopeInfo::Capture &Capture, FieldDecl *Field,
>>          SmallVectorImpl<VarDecl *> &ArrayIndexVars,
>>     -    SmallVectorImpl<unsigned> &ArrayIndexStarts) {
>>     +    SmallVectorImpl<unsigned> &ArrayIndexStarts, bool
>>     ImplicitCapture,
>>     +    SourceLocation CaptureDefaultLoc) {
>>        assert(Capture.isVariableCapture() && "not a variable capture");
>>
>>        auto *Var = Capture.getVariable();
>>     @@ -1399,7 +1399,10 @@
>>        //   An entity captured by a lambda-expression is odr-used (3.2) in
>>        //   the scope containing the lambda-expression.
>>        ExprResult RefResult = S.BuildDeclarationNameExpr(
>>     -      CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(),
>>     Loc), Var);
>>     +      CXXScopeSpec(),
>>     +      DeclarationNameInfo(Var->getDeclName(),
>>     +                          ImplicitCapture ? CaptureDefaultLoc : Loc),
>>     +      Var);
>>        if (RefResult.isInvalid())
>>          return ExprError();
>>        Expr *Ref = RefResult.get();
>>     @@ -1561,7 +1564,8 @@
>>            Expr *Init = From.getInitExpr();
>>            if (!Init) {
>>              auto InitResult = performLambdaVarCaptureInitialization(
>>     -            *this, From, *CurField, ArrayIndexVars,
>>     ArrayIndexStarts);
>>     +            *this, From, *CurField, ArrayIndexVars, ArrayIndexStarts,
>>     +            CaptureDefault != LCD_None, CaptureDefaultLoc);
>>              if (InitResult.isInvalid())
>>                return ExprError();
>>              Init = InitResult.get();
>>     Index: test/CodeGenCXX/debug-lambda-expressions.cpp
>>     ===================================================================
>>     --- test/CodeGenCXX/debug-lambda-expressions.cpp
>>     +++ test/CodeGenCXX/debug-lambda-expressions.cpp
>>     @@ -14,6 +14,19 @@
>>      struct D { D(); D(const D&); int x; };
>>      int d(int x) { D y[10]; return [x,y] { return y[x].x; }(); }
>>
>>     +// CHECK-LABEL: foo
>>     +int foo(int x) {
>>     +// CHECK: [[X:%.+]] = alloca i32,
>>     +// CHECK: call void @llvm.dbg.declare(
>>     +// CHECK: [[X_REF:%.+]] = getelementptr inbounds %{{.+}},
>>     %{{.+}}* %{{.+}}, i32 0, i32 0, !dbg ![[DBG_FOO:[0-9]+]]
>>     +// CHECK: [[X_VAL:%.+]] = load i32, i32* [[X]], align 4, !dbg
>>     ![[DBG_FOO]]
>>     +// CHECK: store i32 [[X_VAL]], i32* [[X_REF]], align 4, !dbg
>>     ![[DBG_FOO]]
>>     +// CHECK: call i32 @{{.+}}, !dbg ![[DBG_FOO]]
>>     +  return [=] {
>>     +    return x;
>>     +  }();
>>     +}
>>     +
>>      // Randomness for file. -- 6
>>      // CHECK: [[FILE:.*]] = !DIFile(filename:
>>     "{{.*}}debug-lambda-expressions.cpp",
>>
>>     @@ -100,3 +113,5 @@
>>      // CHECK-SAME:                          line: [[VAR_LINE]],
>>      // CHECK-SAME:                          elements:
>>     ![[VAR_ARGS:[0-9]+]]
>>      // CHECK: ![[VAR_ARGS]] = !{!{{[0-9]+}}}
>>     +
>>     +// CHECK: [[DBG_FOO:![0-9]+]] = !DILocation(line: 25,
>>
>>
>>
>>     _______________________________________________
>>     cfe-commits mailing list
>>     cfe-commits at lists.llvm.org <mailto:cfe-commits at lists.llvm.org>
>>     http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>>
>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20150825/813ead6a/attachment-0001.html>