================
@@ -151,6 +151,17 @@ def zext_of_shift_amount_combines : GICombineGroup<[
canonicalize_zext_lshr, canonicalize_zext_ashr, canonicalize_zext_shl
]>;
+// Early select of uniform BFX into S_BFE instructions.
+// These instructions encode the offset/width in a way that requires using
+// bitwise operations. Selecting these instructions early allow the combiner
+// to potentially fold these.
+class lower_uniform_bfx<Instruction bfx> : GICombineRule<
+ (defs root:$bfx),
+ (combine (bfx $dst, $src, $o, $w):$bfx, [{ return lowerUniformBFX(*${bfx});
}])>;
+
+def lower_uniform_sbfx : lower_uniform_bfx<G_SBFX>;
+def lower_uniform_ubfx : lower_uniform_bfx<G_UBFX>;
----------------
arsenm wrote:
This needs more elaboration; needs to be clear that this can't be a mandatory
lowering performed in a combiner
https://github.com/llvm/llvm-project/pull/141589
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