[PATCH] D87870: [GISel] Add new combines for G_FMUL

[Jay Foad via Phabricator via llvm-commits]

foad added inline comments.


================
Comment at: llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h:358
 
+  /// Transform G_FMUL(x, -1.0) to G_FSUB(0.0, x)
+  bool applyCombineFMulByNegativeOne(MachineInstr &MI);
----------------
I think this should be "G_FSUB(-0.0, x)".


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Comment at: llvm/include/llvm/Target/GlobalISel/Combine.td:491
 
+// Transform (fmul x, 0.0) -> 0.0
+def fmul_by_zero: GICombineRule<
----------------
This is wrong if x is Inf or NaN.


================
Comment at: llvm/include/llvm/Target/GlobalISel/Combine.td:499
+
+// Transform (fmul x, -1.0) -> (fsub 0.0, x)
+def fmul_by_neg_one: GICombineRule <
----------------
"-0.0".


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D87870/new/

https://reviews.llvm.org/D87870