[llvm] r192124 - [mips] Disable tail merging when long branch pass is enabled.

[Rafael Espíndola]

testcase?

On 7 October 2013 15:13, Akira Hatanaka <ahatanaka at mips.com> wrote:
> Author: ahatanak
> Date: Mon Oct  7 14:13:53 2013
> New Revision: 192124
>
> URL: http://llvm.org/viewvc/llvm-project?rev=192124&view=rev
> Log:
> [mips] Disable tail merging when long branch pass is enabled.
>
> Modified:
>     llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp
>
> Modified: llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp?rev=192124&r1=192123&r2=192124&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp (original)
> +++ llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp Mon Oct  7 14:13:53 2013
> @@ -135,7 +135,13 @@ namespace {
>  class MipsPassConfig : public TargetPassConfig {
>  public:
>    MipsPassConfig(MipsTargetMachine *TM, PassManagerBase &PM)
> -    : TargetPassConfig(TM, PM) {}
> +    : TargetPassConfig(TM, PM) {
> +    // The current implementation of long branch pass requires a scratch
> +    // register ($at) to be available before branch instructions. Tail merging
> +    // can break this requirement, so disable it when long branch pass is
> +    // enabled.
> +    EnableTailMerge = !getMipsSubtarget().enableLongBranchPass();
> +  }
>
>    MipsTargetMachine &getMipsTargetMachine() const {
>      return getTM<MipsTargetMachine>();
>
>
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