From ea81d62d3775ccd81c3957c26ae9ff20f9601cbc Mon Sep 17 00:00:00 2001
From: Jonas Paulsson <paulsson@linux.vnet.ibm.com>
Date: Thu, 29 Oct 2015 16:13:55 +0000
Subject: [PATCH] [SystemZ] Make the CCRegs regclass non-allocatable.

This was discovered to be necessary while running memchr-01.ll with
-verify-machinstrs, because it is not allowed to have a phys reg live
accross block boundaries while on SSA form, if the register is
allocatable (expect in entry block and landing pads).

In this test case, stringRRE pseudos are expanded after isel by adding
a loop block which produces a live out CC register. To make the test
pass, it was also necessary to not say that StringRRELoop pseudo uses
R0L, this is only true for the StringRRE opcode.

-verify-machineinstrs added to memchr-01.ll test.

New test case int-cmp-51.ll to test that MachineCSE can eliminate
an identical compare (which it couldn't do before).

Reviewed by Ulrich Weigand

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251634 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/SystemZ/SystemZInstrFormats.td |  1 +
 lib/Target/SystemZ/SystemZInstrInfo.td    |  6 ++--
 lib/Target/SystemZ/SystemZRegisterInfo.td |  3 +-
 test/CodeGen/SystemZ/int-cmp-51.ll        | 34 +++++++++++++++++++++++
 test/CodeGen/SystemZ/memchr-01.ll         |  2 +-
 5 files changed, 41 insertions(+), 5 deletions(-)
 create mode 100644 test/CodeGen/SystemZ/int-cmp-51.ll

diff --git a/lib/Target/SystemZ/SystemZInstrFormats.td b/lib/Target/SystemZ/SystemZInstrFormats.td
index 71eb9986499..01f4cdec05c 100644
--- a/lib/Target/SystemZ/SystemZInstrFormats.td
+++ b/lib/Target/SystemZ/SystemZInstrFormats.td
@@ -2381,6 +2381,7 @@ multiclass StringRRE<string mnemonic, bits<16> opcode,
   def "" : InstRRE<opcode, (outs GR64:$R1, GR64:$R2),
                    (ins GR64:$R1src, GR64:$R2src),
                    mnemonic#"\t$R1, $R2", []> {
+    let Uses = [R0L];
     let Constraints = "$R1 = $R1src, $R2 = $R2src";
     let DisableEncoding = "$R1src, $R2src";
   }
diff --git a/lib/Target/SystemZ/SystemZInstrInfo.td b/lib/Target/SystemZ/SystemZInstrInfo.td
index 628c51a48ef..b9f2eb5514a 100644
--- a/lib/Target/SystemZ/SystemZInstrInfo.td
+++ b/lib/Target/SystemZ/SystemZInstrInfo.td
@@ -397,7 +397,7 @@ let mayLoad = 1, mayStore = 1 in
   defm MVC : MemorySS<"mvc", 0xD2, z_mvc, z_mvc_loop>;
 
 // String moves.
-let mayLoad = 1, mayStore = 1, Defs = [CC], Uses = [R0L] in
+let mayLoad = 1, mayStore = 1, Defs = [CC] in
   defm MVST : StringRRE<"mvst", 0xB255, z_stpcpy>;
 
 //===----------------------------------------------------------------------===//
@@ -1185,7 +1185,7 @@ let mayLoad = 1, Defs = [CC] in
   defm CLC : MemorySS<"clc", 0xD5, z_clc, z_clc_loop>;
 
 // String comparison.
-let mayLoad = 1, Defs = [CC], Uses = [R0L] in
+let mayLoad = 1, Defs = [CC] in
   defm CLST : StringRRE<"clst", 0xB25D, z_strcmp>;
 
 // Test under mask.
@@ -1459,7 +1459,7 @@ let usesCustomInserter = 1 in {
 }
 
 // Search a block of memory for a character.
-let mayLoad = 1, Defs = [CC], Uses = [R0L] in
+let mayLoad = 1, Defs = [CC] in
   defm SRST : StringRRE<"srst", 0xb25e, z_search_string>;
 
 // Other instructions for inline assembly
diff --git a/lib/Target/SystemZ/SystemZRegisterInfo.td b/lib/Target/SystemZ/SystemZRegisterInfo.td
index 85aa0a62cc7..0d8b08b9cbd 100644
--- a/lib/Target/SystemZ/SystemZRegisterInfo.td
+++ b/lib/Target/SystemZ/SystemZRegisterInfo.td
@@ -282,4 +282,5 @@ def v128any : TypedReg<untyped, VR128>;
 // The 2-bit condition code field of the PSW.  Every register named in an
 // inline asm needs a class associated with it.
 def CC : SystemZReg<"cc">;
-def CCRegs : RegisterClass<"SystemZ", [i32], 32, (add CC)>;
+let isAllocatable = 0 in
+  def CCRegs : RegisterClass<"SystemZ", [i32], 32, (add CC)>;
diff --git a/test/CodeGen/SystemZ/int-cmp-51.ll b/test/CodeGen/SystemZ/int-cmp-51.ll
new file mode 100644
index 00000000000..85a0e4b4d3a
--- /dev/null
+++ b/test/CodeGen/SystemZ/int-cmp-51.ll
@@ -0,0 +1,34 @@
+; Check that modelling of CC/CCRegs does not stop MachineCSE from
+; removing a compare.  MachineCSE will not extend a live range of an
+; allocatable or reserved phys reg.
+;
+; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+
+declare void @bar(i8)
+
+; Check the low end of the CH range.
+define void @f1(i32 %lhs) {
+; CHECK-LABEL: BB#1:
+; CHECK-NOT: cijlh %r0, 1, .LBB0_3
+
+entry:
+  %and188 = and i32 %lhs, 255
+  %cmp189 = icmp ult i32 %and188, 2
+  br i1 %cmp189, label %if.then.191, label %if.else.201
+
+if.then.191:
+  %cmp194 = icmp eq i32 %and188, 1
+  br i1 %cmp194, label %if.then.196, label %if.else.198
+
+if.then.196:
+  call void @bar(i8 1);
+  br label %if.else.201
+
+if.else.198:
+  call void @bar(i8 0);
+  br label %if.else.201
+
+if.else.201:
+  ret void
+}
+
diff --git a/test/CodeGen/SystemZ/memchr-01.ll b/test/CodeGen/SystemZ/memchr-01.ll
index c51690b9848..f7509c4f256 100644
--- a/test/CodeGen/SystemZ/memchr-01.ll
+++ b/test/CodeGen/SystemZ/memchr-01.ll
@@ -1,6 +1,6 @@
 ; Test memchr using SRST, with a weird but usable prototype.
 ;
-; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+; RUN: llc < %s -mtriple=s390x-linux-gnu -verify-machineinstrs | FileCheck %s
 
 declare i8 *@memchr(i8 *%src, i16 %char, i32 %len)
 
-- 
2.34.1