Teach two-address pass to update the "source" map so it doesn't perform a

non-profitable commute using outdated info. The test case would still fail
because of poor pre-RA schedule. That will be fixed by MI scheduler.

rdar://11472010

llvm-svn: 157038

2 files changed, 23 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
index e299671b68b..8164690e40a 100644
--- a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1521,6 +1521,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
 #endif
 
           // Emit a copy or rematerialize the definition.
+          bool isCopy = false;
           const TargetRegisterClass *rc = MRI->getRegClass(regB);
           MachineInstr *DefMI = MRI->getVRegDef(regB);
           // If it's safe and profitable, remat the definition instead of
@@ -1537,10 +1538,11 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
           } else {
             BuildMI(*mbbi, mi, mi->getDebugLoc(), TII->get(TargetOpcode::COPY),
                     regA).addReg(regB);
+            isCopy = true;
           }
 
-          MachineBasicBlock::iterator prevMI = prior(mi);
           // Update DistanceMap.
+          MachineBasicBlock::iterator prevMI = prior(mi);
           DistanceMap.insert(std::make_pair(prevMI, Dist));
           DistanceMap[mi] = ++Dist;
 
@@ -1554,6 +1556,10 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
             RemovedKillFlag = true;
           }
           MO.setReg(regA);
+
+          if (isCopy)
+            // Propagate SrcRegMap.
+            SrcRegMap[regA] = regB;
         }
 
         if (AllUsesCopied) {
diff --git a/llvm/test/CodeGen/X86/2012-05-17-TwoAddressBug.ll b/llvm/test/CodeGen/X86/2012-05-17-TwoAddressBug.ll
new file mode 100644
index 00000000000..171c3f18dc8
--- /dev/null
+++ b/llvm/test/CodeGen/X86/2012-05-17-TwoAddressBug.ll
@@ -0,0 +1,16 @@
+; RUN: llc < %s -mtriple=x86_64-apple-macosx -pre-RA-sched=source | FileCheck %s
+
+; Teach two-address pass to update the "source" map so it doesn't perform a
+; non-profitable commute using outdated info. The test case would still fail
+; because of poor pre-RA schedule. That will be fixed by MI scheduler.
+; rdar://11472010
+define i32 @t(i32 %mask) nounwind readnone ssp {
+entry:
+; CHECK: t:
+; CHECK-NOT: mov
+  %sub = add i32 %mask, -65535
+  %shr = lshr i32 %sub, 23
+  %and = and i32 %mask, 1
+  %add = add i32 %shr, %and
+  ret i32 %add
+}