Mark dead physregdefs dead immediately. This helps MachineSink and

MachineLICM and other things which run before LiveVariables is run.

llvm-svn: 85360

2 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index d3ffb2a22d9..425f670763a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -571,6 +571,8 @@ void InstrEmitter::EmitNode(SDNode *Node, bool IsClone, bool IsCloned,
         unsigned Reg = II.getImplicitDefs()[i - II.getNumDefs()];
         if (Node->hasAnyUseOfValue(i))
           EmitCopyFromReg(Node, i, IsClone, IsCloned, Reg, VRBaseMap);
+        else
+          MI->addRegisterDead(Reg, TRI);
       }
     }
     return;
diff --git a/llvm/test/CodeGen/X86/sink-hoist.ll b/llvm/test/CodeGen/X86/sink-hoist.ll
index 4042a095c6c..7f6366972a9 100644
--- a/llvm/test/CodeGen/X86/sink-hoist.ll
+++ b/llvm/test/CodeGen/X86/sink-hoist.ll
@@ -41,3 +41,18 @@ bb:
 return:
   ret void
 }
+
+; Sink instructions with dead EFLAGS defs.
+
+; CHECK:      je
+; CHECK-NEXT: orb
+
+define zeroext i8 @zzz(i8 zeroext %a, i8 zeroext %b) nounwind readnone {
+entry:
+  %tmp = zext i8 %a to i32                        ; <i32> [#uses=1]
+  %tmp2 = icmp eq i8 %a, 0                    ; <i1> [#uses=1]
+  %tmp3 = or i8 %b, -128                          ; <i8> [#uses=1]
+  %tmp4 = and i8 %b, 127                          ; <i8> [#uses=1]
+  %b_addr.0 = select i1 %tmp2, i8 %tmp4, i8 %tmp3 ; <i8> [#uses=1]
+  ret i8 %b_addr.0
+}