[WebAssembly] Handle multiple loads of splatted loads

Summary:
Fixes an ISel failure when a splatted load is used more than once. The
failure was due to the hacks we were doing in ISel lowering to
preserve the original load as the operand of a LOAD_SPLAT node. The
fix is to properly lower the splatted use of the load to a separate
LOAD_SPLAT node.

Reviewers: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69640

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/WebAssembly/simd-load-splat.ll b/llvm/test/CodeGen/WebAssembly/simd-load-splat.ll
new file mode 100644
index 00000000000..4e693c285a3
--- /dev/null
+++ b/llvm/test/CodeGen/WebAssembly/simd-load-splat.ll
@@ -0,0 +1,21 @@
+; RUN: llc < %s -asm-verbose=false -verify-machineinstrs -disable-wasm-fallthrough-return-opt -wasm-keep-registers -wasm-disable-explicit-locals -mattr=+unimplemented-simd128 | FileCheck %s
+
+; Regression test for an ISel failure when a splatted load had more
+; than one use. The main tests for load_splat are in simd-offset.ll.
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+; CHECK-LABEL: load_splat:
+; CHECK-NEXT: .functype load_splat (i32, i32) -> (i32)
+; CHECK-NEXT: i32.load8_u $[[E:[0-9]+]]=, 0($0){{$}}
+; CHECK-NEXT: v8x16.load_splat $push[[V:[0-9]+]]=, 0($0){{$}}
+; CHECK-NEXT: v128.store 0($1), $pop[[V]]{{$}}
+; CHECK-NEXT: return $[[E]]{{$}}
+define i8 @load_splat(i8* %p, <16 x i8>* %out) {
+  %e = load i8, i8* %p
+  %v1 = insertelement <16 x i8> undef, i8 %e, i32 0
+  %v2 = shufflevector <16 x i8> %v1, <16 x i8> undef, <16 x i32> zeroinitializer
+  store <16 x i8> %v2, <16 x i8>* %out
+  ret i8 %e
+}