[PATCH] [SelectionDAGBuilder] [Review request] incorrect reg class assigned after isel

[Jonas Paulsson via llvm-commits]

ping!

---
 From 8f6c3f6699bbd0dcdfa1fba89101b9f71eae4bb8 Mon Sep 17 00:00:00 2001
From: Jonas Paulsson <paulsson at linux.vnet.ibm.com>
Date: Mon, 2 Nov 2015 09:31:20 +0100
Subject: [PATCH] [SelectionDAGBuilder] Make sure DemoteReg ends up in right
  reg-class.

The virtual register containing the address for returned value on
stack should in the DAG be represented with a CopyFromReg node and not
a Register node. Otherwise, InstrEmitter will not make sure that it
ends up in the right register class for the target instruction.

SystemZ needs this, becuause the reg class for address registers is a
subset of the general 64 bit register class.

test/SystemZ/CodeGen/args-07.ll and args-04.ll updated to run with
-verify-machineinstrs.

---
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 3 ++-
  test/CodeGen/SystemZ/args-04.ll                  | 2 +-
  test/CodeGen/SystemZ/args-07.ll                  | 2 +-
  3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp 
b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 8d04f47..71d2fcc 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1338,7 +1338,8 @@ void SelectionDAGBuilder::visitRet(const 
ReturnInst &I) {
      ComputeValueVTs(TLI, DL, PointerType::getUnqual(F->getReturnType()),
                      PtrValueVTs);

-    SDValue RetPtr = DAG.getRegister(DemoteReg, PtrValueVTs[0]);
+    SDValue RetPtr = DAG.getCopyFromReg(DAG.getEntryNode(), getCurSDLoc(),
+                                        DemoteReg, PtrValueVTs[0]);
      SDValue RetOp = getValue(I.getOperand(0));

      SmallVector<EVT, 4> ValueVTs;
diff --git a/test/CodeGen/SystemZ/args-04.ll 
b/test/CodeGen/SystemZ/args-04.ll
index 48a2cf4..475cceb 100644
--- a/test/CodeGen/SystemZ/args-04.ll
+++ b/test/CodeGen/SystemZ/args-04.ll
@@ -1,7 +1,7 @@
  ; Test incoming GPR, FPR and stack arguments when no extension type is 
given.
  ; This type of argument is used for passing structures, etc.
  ;
-; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+; RUN: llc < %s -mtriple=s390x-linux-gnu -verify-machineinstrs | 
FileCheck %s

  ; Do some arithmetic so that we can see the register being used.
  define i8 @f1(i8 %r2) {
diff --git a/test/CodeGen/SystemZ/args-07.ll 
b/test/CodeGen/SystemZ/args-07.ll
index 29d9b31..44a31fa 100644
--- a/test/CodeGen/SystemZ/args-07.ll
+++ b/test/CodeGen/SystemZ/args-07.ll
@@ -1,6 +1,6 @@
  ; Test multiple return values (LLVM ABI extension)
  ;
-; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+; RUN: llc < %s -mtriple=s390x-linux-gnu -verify-machineinstrs| 
FileCheck %s

  ; Up to four integer return values fit into GPRs.
  define { i64, i64, i64, i64 } @f1() {
-- 
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