[llvm-commits] [llvm] r106878 - /llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp

[Bill Wendling]

This patch is from a suggestion by Jacob!

-bw

On Jun 25, 2010, at 1:42 PM, Bill Wendling wrote:

> Author: void
> Date: Fri Jun 25 15:42:55 2010
> New Revision: 106878
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=106878&view=rev
> Log:
> We should remove the live range from the destination register only if *all* defs
> are dead, not just the def of this register. I.e., a register could be dead, but
> it's subreg isn't.
> 
> Testcase to follow with a subsequent patch.
> 
> Modified:
>    llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
> 
> Modified: llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp?rev=106878&r1=106877&r2=106878&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp Fri Jun 25 15:42:55 2010
> @@ -1892,8 +1892,8 @@
>         if (li_->hasInterval(SrcReg)) {
>           LiveInterval &RegInt = li_->getInterval(SrcReg);
>           // If def of this move instruction is dead, remove its live range
> -          // from the dstination register's live interval.
> -          if (MI->registerDefIsDead(DstReg)) {
> +          // from the destination register's live interval.
> +          if (MI->allDefsAreDead()) {
>             if (!ShortenDeadCopySrcLiveRange(RegInt, MI))
>               ShortenDeadCopyLiveRange(RegInt, MI);
>           } else {
> 
> 
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