[CodeGenPrepare] Respect endianness in splitMergedValStore.

splitMergedValStore will split a store into two if target prefers this, or if
-force-split-store is passed.

This patch adds the missing handling for endianness in this function along
with a test case.

Review: Eli Friedman
https://reviews.llvm.org/D44396

llvm-svn: 327375

1 files changed, 22 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/SystemZ/codegenprepare-splitstore.ll b/llvm/test/CodeGen/SystemZ/codegenprepare-splitstore.ll
new file mode 100644
index 00000000000..0b1e2b477c2
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/codegenprepare-splitstore.ll
@@ -0,0 +1,22 @@
+; Test that CodeGenPrepare respects endianness when splitting a store.
+;
+; RUN: llc -mtriple=s390x-linux-gnu -mcpu=z13 -force-split-store < %s  | FileCheck %s
+
+define void @fun(i16* %Src, i16* %Dst) {
+; CHECK-LABEL: # %bb.0:
+; CHECK:       lh   %r0, 0(%r2)
+; CHECK-NEXT:  stc  %r0, 1(%r3)
+; CHECK-NEXT:  srl  %r0, 8
+; CHECK-NEXT:  stc  %r0, 0(%r3)
+; CHECK-NEXT:  br   %r14
+  %1 = load i16, i16* %Src
+  %2 = trunc i16 %1 to i8
+  %3 = lshr i16 %1, 8
+  %4 = trunc i16 %3 to i8
+  %5 = zext i8 %2 to i16
+  %6 = zext i8 %4 to i16
+  %7 = shl nuw i16 %6, 8
+  %8 = or i16 %7, %5
+  store i16 %8, i16* %Dst
+  ret void
+}