[llvm-commits] [llvm] r172027 - in /llvm/trunk: include/llvm/CodeGen/MachineFrameInfo.h lib/CodeGen/MachineFunction.cpp lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp test/CodeGen/ARM/alloc-no-stack-realign-error.ll test/CodeGen/ARM/alloc-no-stack-realign.ll

[Bob Wilson]

On Jan 9, 2013, at 5:10 PM, Manman Ren <mren at apple.com> wrote:

> Author: mren
> Date: Wed Jan  9 19:10:10 2013
> New Revision: 172027
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=172027&view=rev
> Log:
> Stack Alignment: throw error if we can't satisfy the minimal alignment
> requirement when creating stack objects in MachineFrameInfo.
> 
> Add CreateStackObjectWithMinAlign to throw error when the minimal alignment
> can't be achieved and to clamp the alignment when the preferred alignment
> can't be achieved. Same is true for CreateVariableSizedObject.
> Will not emit error in CreateSpillStackObject or CreateStackObject.
> 
> As long as callers of CreateStackObject do not assume the object will be
> aligned at the requested alignment, we should not have miscompile since
> later optimizations which look at the object's alignment will have the correct
> information.
> 
> rdar://12713765
> 
> 
> Modified: llvm/trunk/lib/CodeGen/MachineFunction.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineFunction.cpp?rev=172027&r1=172026&r2=172027&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/MachineFunction.cpp (original)
> +++ llvm/trunk/lib/CodeGen/MachineFunction.cpp Wed Jan  9 19:10:10 2013
> @@ -473,24 +473,32 @@
> }
> 
> /// clampStackAlignment - Clamp the alignment if requested and emit a warning.
> -static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned Align,
> -                                           unsigned StackAlign) {
> -  if (!ShouldClamp || Align <= StackAlign)
> -    return Align;
> -  DEBUG(dbgs() << "Warning: requested alignment " << Align
> -               << " exceeds the stack alignment " << StackAlign
> -               << " when stack realignment is off" << '\n');
> +static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned PrefAlign,
> +                         unsigned MinAlign, unsigned StackAlign,
> +                         const AllocaInst *Alloca = 0) {
> +  if (!ShouldClamp || PrefAlign <= StackAlign)
> +    return PrefAlign;
> +  if (Alloca && MinAlign > StackAlign)
> +    Alloca->getParent()->getContext().emitError(Alloca,
> +        "Requested Minimal Alignment exceeds the Stack Alignment!");
> +  else
> +    assert(MinAlign <= StackAlign &&
> +           "Requested Minimal Alignment exceeds the Stack Alignment!");
>   return StackAlign;
> }

We don't usually capitalize diagnostic messages like that.  Please change the message to be all lowercase.  I think you could also drop the "minimal".