[llvm-commits] [llvm] r91381 - in /llvm/trunk: lib/Target/X86/X86ISelLowering.cpp lib/Target/X86/X86ISelLowering.h lib/Target/X86/X86Instr64bit.td lib/Target/X86/X86InstrInfo.td test/CodeGen/X86/setcc.ll

[Dan Gohman]

On Dec 14, 2009, at 4:53 PM, Evan Cheng wrote:
> 
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/X86Instr64bit.td (original)
> +++ llvm/trunk/lib/Target/X86/X86Instr64bit.td Mon Dec 14 18:53:42 2009
> @@ -1333,6 +1333,15 @@
>                                      X86_COND_NO, EFLAGS))]>, TB;
> } // isTwoAddress
> 
> +// Use sbb to materialize carry flag into a GPR.
> +let Defs = [EFLAGS], Uses = [EFLAGS], isCodeGenOnly = 1 in
> +def SETB_C64r : RI<0x19, MRMDestReg, (outs GR64:$dst), (ins),
> +                  "sbb{q}\t$dst, $dst",
> +                 [(set GR64:$dst, (zext (X86setcc_c X86_COND_B, EFLAGS)))]>;

An sbbq will set all 64 bits. Why does the pattern here have a zext in it?

Dan