[llvm] [DAG] SelectionDAG::canCreateUndefOrPoison - Mark AVGFLOORS and AVGCEILS as safe (PR #148191)

[Simon Pilgrim via llvm-commits]

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+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+
+; RUN: llc < %s -march=arm64 -mattr=+neon | FileCheck %s
+; Test that the presence of 'freeze' does not block instruction selection of:
+; - uhadd
+; - urhadd
+; - shadd
+; - srhadd
+
+declare <8 x i16> @llvm.aarch64.neon.uhadd.v8i16(<8 x i16>, <8 x i16>)
+declare <8 x i16> @llvm.aarch64.neon.urhadd.v8i16(<8 x i16>, <8 x i16>)
+declare <8 x i16> @llvm.aarch64.neon.shadd.v8i16(<8 x i16>, <8 x i16>)
+declare <8 x i16> @llvm.aarch64.neon.srhadd.v8i16(<8 x i16>, <8 x i16>)
+
+;===---------------------------------------------------------------------===;
+; Test: freeze does not block uhadd instruction selection
+;===---------------------------------------------------------------------===;
+
+define <8 x i16> @uhadd_freeze(<8 x i16> %a0, <8 x i16> %a1) {
+; CHECK-LABEL: uhadd_freeze:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    movi v2.8h, #15
+; CHECK-NEXT:    and v0.16b, v0.16b, v2.16b
+; CHECK-NEXT:    and v1.16b, v1.16b, v2.16b
+; CHECK-NEXT:    movi v2.8h, #31
+; CHECK-NEXT:    uhadd v0.8h, v0.8h, v1.8h
+; CHECK-NEXT:    and v0.16b, v0.16b, v2.16b
+; CHECK-NEXT:    ret
+  %m0 = and <8 x i16> %a0, <i16 15, i16 15, i16 15, i16 15, i16 15, i16 15, i16 15, i16 15>
+  %m1 = and <8 x i16> %a1, <i16 15, i16 15, i16 15, i16 15, i16 15, i16 15, i16 15, i16 15>
+  %avg = call <8 x i16> @llvm.aarch64.neon.uhadd.v8i16(<8 x i16> %m0, <8 x i16> %m1)
+  %frozen = freeze <8 x i16> %avg
+  %masked = and <8 x i16> %frozen, <i16 31, i16 31, i16 31, i16 31, i16 31, i16 31, i16 31, i16 31>
+  ret <8 x i16> %masked
+}
+
+;===---------------------------------------------------------------------===;
+; Test: freeze does not block urhadd instruction selection
+;===---------------------------------------------------------------------===;
+
+define <8 x i16> @urhadd_freeze(<8 x i16> %a0, <8 x i16> %a1) {
+; CHECK-LABEL: urhadd_freeze:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    movi v2.8h, #15
+; CHECK-NEXT:    and v0.16b, v0.16b, v2.16b
+; CHECK-NEXT:    and v1.16b, v1.16b, v2.16b
+; CHECK-NEXT:    movi v2.8h, #31
+; CHECK-NEXT:    urhadd v0.8h, v0.8h, v1.8h
+; CHECK-NEXT:    and v0.16b, v0.16b, v2.16b
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RKSimon wrote:

This and should have gone - any idea why it hasn't?

https://github.com/llvm/llvm-project/pull/148191