Fix small bug in handling instructions with more than one implicitly defined operand.

ProcessImplicitDefs would only mark one operand per instruction with <undef>.
This fixed PR6086.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95319 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ProcessImplicitDefs.cpp b/lib/CodeGen/ProcessImplicitDefs.cpp
index a00f450..a0a781b 100644
--- a/lib/CodeGen/ProcessImplicitDefs.cpp
+++ b/lib/CodeGen/ProcessImplicitDefs.cpp
@@ -264,8 +264,8 @@
         }
       }
       RUses.clear();
+      ModInsts.clear();
     }
-    ModInsts.clear();
     ImpDefRegs.clear();
     ImpDefMIs.clear();
   }
diff --git a/test/CodeGen/X86/2010-02-03-DualUndef.ll b/test/CodeGen/X86/2010-02-03-DualUndef.ll
new file mode 100644
index 0000000..d116ecc
--- /dev/null
+++ b/test/CodeGen/X86/2010-02-03-DualUndef.ll
@@ -0,0 +1,27 @@
+; RUN: llc < %s -march=x86-64
+; PR6086
+define fastcc void @prepOutput() nounwind {
+bb:                                               ; preds = %output.exit
+  br label %bb.i1
+
+bb.i1:                                            ; preds = %bb7.i, %bb
+  br i1 undef, label %bb7.i, label %bb.nph.i
+
+bb.nph.i:                                         ; preds = %bb.i1
+  br label %bb3.i
+
+bb3.i:                                            ; preds = %bb5.i6, %bb.nph.i
+  %tmp10.i = trunc i64 undef to i32               ; <i32> [#uses=1]
+  br i1 undef, label %bb4.i, label %bb5.i6
+
+bb4.i:                                            ; preds = %bb3.i
+  br label %bb5.i6
+
+bb5.i6:                                           ; preds = %bb4.i, %bb3.i
+  %0 = phi i32 [ undef, %bb4.i ], [ undef, %bb3.i ] ; <i32> [#uses=1]
+  %1 = icmp slt i32 %0, %tmp10.i                  ; <i1> [#uses=1]
+  br i1 %1, label %bb7.i, label %bb3.i
+
+bb7.i:                                            ; preds = %bb5.i6, %bb.i1
+  br label %bb.i1
+}