[llvm-commits] [PATCH] optimization of -(x != 0) to use neg in X86

[Chad Rosier]

Manman,

+      if (ConstantSDNode *YC = dyn_cast<ConstantSDNode>(Y))
+        if (YC && YC->isNullValue() && 
+            (isAllOnes(Op1) == (CondCode == X86::COND_NE))) {

The dyn_cast<> operator returns null if the operand is not of the correct type.  Thus, the "YC &&" check is not necessary.

 Chad

On Apr 27, 2012, at 6:03 PM, manman ren wrote:

> 
> This patch will optimize -(x != 0) on X86
> FROM 
> cmpl	$0x01,%edi
> sbbl	%eax,%eax
> notl	%eax
> TO
> negl %edi
> sbbl %eax %eax
> 
> Please review & provide feedback,
> Thanks,
> Manman
> 
> <sext_ne.patch>
> 
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