From bc96bcdaf9bd4d61cae955cf7b54c108947208cd Mon Sep 17 00:00:00 2001
From: Manman Ren <mren@apple.com>
Date: Fri, 28 Sep 2012 18:53:24 +0000
Subject: [PATCH] X86: when replacing SUB with TEST in ISelDAGToDAG, only
 replace uses of the second output of SUB with first output of TEST.

PR13966


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164835 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86ISelDAGToDAG.cpp | 33 +++++++++++++++++++++++++-----
 1 file changed, 28 insertions(+), 5 deletions(-)

diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 40605afb699..b4c71548a2b 100644
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -2525,7 +2525,13 @@ SDNode *X86DAGToDAGISel::Select(SDNode *Node) {
                                                         MVT::i8, Reg);
 
         // Emit a testb.
-        return CurDAG->getMachineNode(X86::TEST8ri, dl, MVT::i32, Subreg, Imm);
+        SDNode *NewNode = CurDAG->getMachineNode(X86::TEST8ri, dl, MVT::i32,
+                                                 Subreg, Imm);
+        // Replace SUB|CMP with TEST, since SUB has two outputs while TEST has
+        // one, do not call ReplaceAllUsesWith.
+        ReplaceUses(SDValue(Node, (Opcode == X86ISD::SUB ? 1 : 0)),
+                    SDValue(NewNode, 0));
+        return NULL;
       }
 
       // For example, "testl %eax, $2048" to "testb %ah, $8".
@@ -2556,8 +2562,13 @@ SDNode *X86DAGToDAGISel::Select(SDNode *Node) {
         // Emit a testb.  The EXTRACT_SUBREG becomes a COPY that can only
         // target GR8_NOREX registers, so make sure the register class is
         // forced.
-        return CurDAG->getMachineNode(X86::TEST8ri_NOREX, dl, MVT::i32,
-                                      Subreg, ShiftedImm);
+        SDNode *NewNode = CurDAG->getMachineNode(X86::TEST8ri_NOREX, dl,
+                                                 MVT::i32, Subreg, ShiftedImm);
+        // Replace SUB|CMP with TEST, since SUB has two outputs while TEST has
+        // one, do not call ReplaceAllUsesWith.
+        ReplaceUses(SDValue(Node, (Opcode == X86ISD::SUB ? 1 : 0)),
+                    SDValue(NewNode, 0));
+        return NULL;
       }
 
       // For example, "testl %eax, $32776" to "testw %ax, $32776".
@@ -2573,7 +2584,13 @@ SDNode *X86DAGToDAGISel::Select(SDNode *Node) {
                                                         MVT::i16, Reg);
 
         // Emit a testw.
-        return CurDAG->getMachineNode(X86::TEST16ri, dl, MVT::i32, Subreg, Imm);
+        SDNode *NewNode = CurDAG->getMachineNode(X86::TEST16ri, dl, MVT::i32,
+                                                 Subreg, Imm);
+        // Replace SUB|CMP with TEST, since SUB has two outputs while TEST has
+        // one, do not call ReplaceAllUsesWith.
+        ReplaceUses(SDValue(Node, (Opcode == X86ISD::SUB ? 1 : 0)),
+                    SDValue(NewNode, 0));
+        return NULL;
       }
 
       // For example, "testq %rax, $268468232" to "testl %eax, $268468232".
@@ -2589,7 +2606,13 @@ SDNode *X86DAGToDAGISel::Select(SDNode *Node) {
                                                         MVT::i32, Reg);
 
         // Emit a testl.
-        return CurDAG->getMachineNode(X86::TEST32ri, dl, MVT::i32, Subreg, Imm);
+        SDNode *NewNode = CurDAG->getMachineNode(X86::TEST32ri, dl, MVT::i32,
+                                                 Subreg, Imm);
+        // Replace SUB|CMP with TEST, since SUB has two outputs while TEST has
+        // one, do not call ReplaceAllUsesWith.
+        ReplaceUses(SDValue(Node, (Opcode == X86ISD::SUB ? 1 : 0)),
+                    SDValue(NewNode, 0));
+        return NULL;
       }
     }
     break;