[llvm-commits] [llvm] r164926 - /llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp

[Chandler Carruth]

On Mon, Oct 1, 2012 at 12:33 AM, Craig Topper <craig.topper at gmail.com>wrote:

> Author: ctopper
> Date: Mon Oct  1 02:33:27 2012
> New Revision: 164926
>
> URL: http://llvm.org/viewvc/llvm-project?rev=164926&view=rev
> Log:
> Use constants for all return values in switch. Allows clang to optimize it
> into a lookup table.
>
> Modified:
>     llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
>
> Modified: llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp?rev=164926&r1=164925&r2=164926&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp (original)
> +++ llvm/trunk/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp Mon Oct  1
> 02:33:27 2012
> @@ -243,9 +243,14 @@
>    case X86::R15: case X86::R15D: case X86::R15W: case X86::R15B:
>      return N86::EDI;
>
> -  case X86::ST0: case X86::ST1: case X86::ST2: case X86::ST3:
> -  case X86::ST4: case X86::ST5: case X86::ST6: case X86::ST7:
> -    return RegNo-X86::ST0;
> +  case X86::ST0: return 0;
> +  case X86::ST1: return 1;
> +  case X86::ST2: return 2;
> +  case X86::ST3: return 3;
> +  case X86::ST4: return 4;
> +  case X86::ST5: return 5;
> +  case X86::ST6: return 6;
> +  case X86::ST7: return 7;
>

Out of curiosity, why are we unable to form the lookup table out of this?
It seems like a common pattern that should be directly supported.
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