Handle cases where a register and one of its super-register are both marked as

defined on the same instruction. This fixes PR1767.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43699 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 2 deletions

diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 57396b7416..7e8965ea84 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -203,7 +203,7 @@ bool LiveVariables::addRegisterKilled(unsigned IncomingReg, MachineInstr *MI,
                  RegInfo->isSuperRegister(IncomingReg, Reg) &&
                  MO.isKill())
         // A super-register kill already exists.
-        return true;
+        Found = true;
     }
   }
 
@@ -357,7 +357,9 @@ void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI) {
     } else if (PhysRegPartUse[Reg])
       // Add implicit use / kill to last partial use.
       addRegisterKilled(Reg, PhysRegPartUse[Reg], true);
-    else
+    else if (LastRef != MI)
+      // Defined, but not used. However, watch out for cases where a super-reg
+      // is also defined on the same MI.
       addRegisterDead(Reg, LastRef);
   }
 
diff --git a/test/CodeGen/X86/2007-11-04-LiveVariablesBug.ll b/test/CodeGen/X86/2007-11-04-LiveVariablesBug.ll
new file mode 100644
index 0000000000..7e41f36790
--- /dev/null
+++ b/test/CodeGen/X86/2007-11-04-LiveVariablesBug.ll
@@ -0,0 +1,16 @@
+; RUN: llvm-as < %s | llc -mtriple=x86_64-unknown-linux-gnu
+; PR1767
+
+define void @xor_sse_2(i64 %bytes, i64* %p1, i64* %p2) {
+entry:
+        %p2_addr = alloca i64*          ; <i64**> [#uses=2]
+        %lines = alloca i32             ; <i32*> [#uses=2]
+        store i64* %p2, i64** %p2_addr, align 8
+        %tmp1 = lshr i64 %bytes, 8              ; <i64> [#uses=1]
+        %tmp12 = trunc i64 %tmp1 to i32         ; <i32> [#uses=2]
+        store i32 %tmp12, i32* %lines, align 4
+        %tmp6 = call i64* asm sideeffect "foo",
+"=r,=*r,=*r,r,0,1,2,~{dirflag},~{fpsr},~{flags},~{memory}"( i64** %p2_addr,
+i32* %lines, i64 256, i64* %p1, i64* %p2, i32 %tmp12 )              ; <i64*> [#uses=0]
+        ret void
+}