[SystemZ] Extend memcpy and memset support to all constant lengths

Lengths up to a certain threshold (currently 6 * 256) use a series of MVCs.
Lengths above that threshold use a loop to handle X*256 bytes followed
by a single MVC to handle the excess (if any).  This loop will also be
needed in future when support for variable lengths is added.

Because the same tablegen classes are used to define MVC and CLC,
the patch also has the side-effect of defining a pseudo loop instruction
for CLC.  That instruction isn't used yet (and wouldn't be handled correctly
if it were).  I'm planning to use it soon though.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189331 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 42 insertions, 6 deletions

diff --git a/test/CodeGen/SystemZ/memset-01.ll b/test/CodeGen/SystemZ/memset-01.ll
index b272a5bcc6..f17901cc73 100644
--- a/test/CodeGen/SystemZ/memset-01.ll
+++ b/test/CodeGen/SystemZ/memset-01.ll
@@ -103,22 +103,58 @@ define void @f10(i8 *%dest, i8 %val) {
   ret void
 }
 
-; 258 bytes, i32 version.  258 bytes is too big for a single MVC.
-; For now expect none, so that the test fails and gets updated when
-; large copies are implemented.
+; 258 bytes, i32 version.  We need two MVCs.
 define void @f11(i8 *%dest, i8 %val) {
 ; CHECK-LABEL: f11:
-; CHECK-NOT: mvc
+; CHECK: stc %r3, 0(%r2)
+; CHECK: mvc 1(256,%r2), 0(%r2)
+; CHECK: mvc 257(1,%r2), 256(%r2)
 ; CHECK: br %r14
   call void @llvm.memset.p0i8.i32(i8 *%dest, i8 %val, i32 258, i32 1, i1 false)
   ret void
 }
 
-; 258 bytes, i64 version, with the same comments as above.
+; 258 bytes, i64 version.
 define void @f12(i8 *%dest, i8 %val) {
 ; CHECK-LABEL: f12:
-; CHECK-NOT: mvc
+; CHECK: stc %r3, 0(%r2)
+; CHECK: mvc 1(256,%r2), 0(%r2)
+; CHECK: mvc 257(1,%r2), 256(%r2)
 ; CHECK: br %r14
   call void @llvm.memset.p0i8.i64(i8 *%dest, i8 %val, i64 258, i32 1, i1 false)
   ret void
 }
+
+; Test the largest case for which straight-line code is used.
+define void @f13(i8 *%dest, i8 %val) {
+; CHECK-LABEL: f13:
+; CHECK: stc %r3, 0(%r2)
+; CHECK: mvc 1(256,%r2), 0(%r2)
+; CHECK: mvc 257(256,%r2), 256(%r2)
+; CHECK: mvc 513(256,%r2), 512(%r2)
+; CHECK: mvc 769(256,%r2), 768(%r2)
+; CHECK: mvc 1025(256,%r2), 1024(%r2)
+; CHECK: mvc 1281(256,%r2), 1280(%r2)
+; CHECK: br %r14
+  call void @llvm.memset.p0i8.i64(i8 *%dest, i8 %val, i64 1537, i32 1,
+                                  i1 false)
+  ret void
+}
+
+; Test the next size up, which uses a loop.  We leave the other corner
+; cases to memcpy-01.ll.
+define void @f14(i8 *%dest, i8 %val) {
+; CHECK-LABEL: f14:
+; CHECK: stc %r3, 0(%r2)
+; CHECK: lghi [[COUNT:%r[0-5]]], 6
+; CHECK: [[LABEL:\.L[^:]*]]:
+; CHECK: pfd 2, 769(%r2)
+; CHECK: mvc 1(256,%r2), 0(%r2)
+; CHECK: la %r2, 256(%r2)
+; CHECK: brctg [[COUNT]], [[LABEL]]
+; CHECK: mvc 1(1,%r2), 0(%r2)
+; CHECK: br %r14
+  call void @llvm.memset.p0i8.i64(i8 *%dest, i8 %val, i64 1538, i32 1,
+                                  i1 false)
+  ret void
+}