[llvm] [WASM] Fold bitselect with splat zero (PR #147305)

[Luke Lau via llvm-commits]

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@@ -0,0 +1,48 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s  -O3 -verify-machineinstrs -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -mattr=+simd128 | FileCheck %s
+target triple = "wasm32-unknown-unknown"
+
+define void @bitselect_first_zero(ptr %output, ptr  %input) {
+; CHECK-LABEL: bitselect_first_zero:
+; CHECK:         .functype bitselect_first_zero (i32, i32) -> ()
+; CHECK-NEXT:  # %bb.0: # %start
+; CHECK-NEXT:    v128.load $push6=, 0($1)
+; CHECK-NEXT:    local.tee $push5=, $2=, $pop6
+; CHECK-NEXT:    v128.const $push0=, 2139095040, 2139095040, 2139095040, 2139095040
+; CHECK-NEXT:    v128.and $push1=, $2, $pop0
+; CHECK-NEXT:    v128.const $push2=, 0, 0, 0, 0
+; CHECK-NEXT:    i32x4.ne $push3=, $pop1, $pop2
+; CHECK-NEXT:    v128.and $push4=, $pop5, $pop3
+; CHECK-NEXT:    v128.store 0($0), $pop4
+; CHECK-NEXT:    return
+start:
+  %input.val = load <4 x i32>, ptr %input, align 16
+  %0 = and <4 x i32> %input.val, splat (i32 2139095040)
+  %1 = icmp eq <4 x i32> %0, zeroinitializer
+  %2 = select <4 x i1> %1, <4 x i32> zeroinitializer, <4 x i32> %input.val
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lukel97 wrote:

Can we add two test cases without the and + icmp? Since I think with the `select` on its own we should see still the bitselect get converted to an and

https://github.com/llvm/llvm-project/pull/147305