From ccf6aaba910a9669fbf123282e681686b8447d2e Mon Sep 17 00:00:00 2001
From: Nemanja Ivanovic <nemanja.i.ibm@gmail.com>
Date: Tue, 8 Aug 2017 13:52:45 +0000
Subject: [PATCH] [PowerPC] Don't crash on larger splats achieved through
 1-byte splats

We've implemented a 1-byte splat using XXSPLTISB on P9. However, LLVM will
produce a 1-byte splat even for wider element BUILD_VECTOR nodes. This patch
prevents crashing in that situation.

Differential Revision: https://reviews.llvm.org/D35650


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310358 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/PowerPC/PPCISelLowering.cpp        |  9 +++++++++
 .../PowerPC/splat-larger-types-as-v16i8.ll    | 20 +++++++++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 test/CodeGen/PowerPC/splat-larger-types-as-v16i8.ll

diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 2c0936b1c64..204bdcc329c 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -7650,6 +7650,15 @@ SDValue PPCTargetLowering::LowerBUILD_VECTOR(SDValue Op,
         return DAG.getBitcast(Op.getValueType(), NewBV);
       return NewBV;
     }
+
+    // BuildVectorSDNode::isConstantSplat() is actually pretty smart. It'll
+    // detect that constant splats like v8i16: 0xABAB are really just splats
+    // of a 1-byte constant. In this case, we need to convert the node to a
+    // splat of v16i8 and a bitcast.
+    if (Op.getValueType() != MVT::v16i8)
+      return DAG.getBitcast(Op.getValueType(),
+                            DAG.getConstant(SplatBits, dl, MVT::v16i8));
+
     return Op;
   }
 
diff --git a/test/CodeGen/PowerPC/splat-larger-types-as-v16i8.ll b/test/CodeGen/PowerPC/splat-larger-types-as-v16i8.ll
new file mode 100644
index 00000000000..2ae61f1bb57
--- /dev/null
+++ b/test/CodeGen/PowerPC/splat-larger-types-as-v16i8.ll
@@ -0,0 +1,20 @@
+; RUN: llc -mcpu=pwr9 -mtriple=powerpc64-unknown-unknown < %s | FileCheck %s
+; RUN: llc -mcpu=pwr9 -mtriple=powerpc64le-unknown-unknown < %s | FileCheck %s
+define <8 x i16> @test1() {
+entry:
+  ret <8 x i16> <i16 257, i16 257, i16 257, i16 257, i16 257, i16 257, i16 257, i16 257>
+; CHECK-LABEL: test1
+; CHECK: xxspltib 34, 1
+}
+define <8 x i16> @testAB() {
+entry:
+; CHECK-LABEL: testAB
+; CHECK: xxspltib 34, 171
+  ret <8 x i16> <i16 43947, i16 43947, i16 43947, i16 43947, i16 43947, i16 43947, i16 43947, i16 43947>
+}
+define <4 x i32> @testAB32() {
+entry:
+; CHECK-LABEL: testAB32
+; CHECK: xxspltib 34, 171
+  ret <4 x i32> <i32 2880154539, i32 2880154539, i32 2880154539, i32 2880154539>
+}
-- 
2.40.0