[llvm] r174336 - [Stack Alignment] emit warning instead of a hard error

[Manman Ren]

Sorry about committing this before the official announcement :[

Manman

On Feb 4, 2013, at 3:45 PM, Manman Ren <mren at apple.com> wrote:

> Author: mren
> Date: Mon Feb  4 17:45:08 2013
> New Revision: 174336
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=174336&view=rev
> Log:
> [Stack Alignment] emit warning instead of a hard error
> 
> Per discussion in rdar://13127907, we should emit a hard error only if
> people write code where the requested alignment is larger than achievable
> and assumes the low bits are zeros. A warning should be good enough when
> we are not sure if the source code assumes the low bits are zeros.
> 
> rdar://13127907
> 
> Modified:
>    llvm/trunk/lib/CodeGen/MachineFunction.cpp
>    llvm/trunk/test/CodeGen/ARM/alloc-no-stack-realign-error.ll
> 
> Modified: llvm/trunk/lib/CodeGen/MachineFunction.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineFunction.cpp?rev=174336&r1=174335&r2=174336&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/MachineFunction.cpp (original)
> +++ llvm/trunk/lib/CodeGen/MachineFunction.cpp Mon Feb  4 17:45:08 2013
> @@ -479,11 +479,11 @@ static inline unsigned clampStackAlignme
>   if (!ShouldClamp || PrefAlign <= StackAlign)
>     return PrefAlign;
>   if (Alloca && MinAlign > StackAlign)
> -    Alloca->getParent()->getContext().emitError(Alloca,
> -        "Requested Minimal Alignment exceeds the Stack Alignment!");
> +    Alloca->getParent()->getContext().emitWarning(Alloca,
> +        "Requested alignment exceeds the stack alignment!");
>   else
>     assert(MinAlign <= StackAlign &&
> -           "Requested Minimal Alignment exceeds the Stack Alignment!");
> +           "Requested alignment exceeds the stack alignment!");
>   return StackAlign;
> }
> 
> 
> Modified: llvm/trunk/test/CodeGen/ARM/alloc-no-stack-realign-error.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/alloc-no-stack-realign-error.ll?rev=174336&r1=174335&r2=174336&view=diff
> ==============================================================================
> --- llvm/trunk/test/CodeGen/ARM/alloc-no-stack-realign-error.ll (original)
> +++ llvm/trunk/test/CodeGen/ARM/alloc-no-stack-realign-error.ll Mon Feb  4 17:45:08 2013
> @@ -6,10 +6,10 @@
> ; If alignment for alloc is smaller than or equal to stack alignment, but the 
> ; preferred type alignment is bigger, the alignment will be clamped.
> ; If alignment for alloca is bigger than stack alignment, the compiler
> -; will emit an error.
> +; will emit a warning.
> define void @test(<16 x float>* noalias sret %agg.result) nounwind ssp {
> entry:
> -; CHECK: Requested Minimal Alignment exceeds the Stack Alignment!
> +; CHECK: warning: Requested alignment exceeds the stack alignment!
>  %retval = alloca <16 x float>, align 16
>  %0 = load <16 x float>* @T3_retval, align 16
>  store <16 x float> %0, <16 x float>* %retval
> 
> 
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