[llvm] [GlobalISel] Add a fadd 0.0 combine with nsz (PR #153748)

[Matt Arsenault via llvm-commits]

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@@ -560,6 +560,13 @@ def right_identity_neg_zero_fp: GICombineRule<
   (apply (GIReplaceReg $dst, $x))
 >;
 
+def right_identity_neg_zero_fp_nsz: GICombineRule<
+  (defs root:$dst),
+  (match (G_FADD $dst, $x, $y, (MIFlags FmNsz)):$root,
+    [{ return Helper.matchConstantFPOp(${y}, 0.0); }]),
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arsenm wrote:

We probably should have a dedicated isZero mirroring afloat 

https://github.com/llvm/llvm-project/pull/153748