[llvm] r290014 - AArch64: Enable post-ra liveness updates

[Matthias Braun via llvm-commits]

Author: matze
Date: Fri Dec 16 17:55:43 2016
New Revision: 290014

URL: http://llvm.org/viewvc/llvm-project?rev=290014&view=rev
Log:
AArch64: Enable post-ra liveness updates

Differential Revision: https://reviews.llvm.org/D27559

Modified:
    llvm/trunk/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
    llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
    llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.h
    llvm/trunk/test/CodeGen/AArch64/ldst-opt-dbg-limit.mir
    llvm/trunk/test/CodeGen/AArch64/movimm-wzr.mir

Modified: llvm/trunk/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp?rev=290014&r1=290013&r2=290014&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp Fri Dec 16 17:55:43 2016
@@ -897,9 +897,14 @@ bool AArch64ExpandPseudo::expandMI(Machi
   case AArch64::MOVi64imm:
     return expandMOVImm(MBB, MBBI, 64);
   case AArch64::RET_ReallyLR: {
+    // Hiding the LR use with RET_ReallyLR may lead to extra kills in the
+    // function and missing live-ins. We are fine in practice because callee
+    // saved register handling ensures the register value is restored before
+    // RET, but we need the undef flag here to appease the MachineVerifier
+    // liveness checks.
     MachineInstrBuilder MIB =
         BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(AArch64::RET))
-          .addReg(AArch64::LR);
+          .addReg(AArch64::LR, RegState::Undef);
     transferImpOps(MI, MIB, MIB);
     MI.eraseFromParent();
     return true;

Modified: llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp?rev=290014&r1=290013&r2=290014&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp Fri Dec 16 17:55:43 2016
@@ -767,6 +767,7 @@ AArch64LoadStoreOpt::promoteLoadFromStor
     // Remove the load, if the destination register of the loads is the same
     // register for stored value.
     if (StRt == LdRt && LoadSize == 8) {
+      StoreI->clearRegisterKills(StRt, TRI);
       DEBUG(dbgs() << "Remove load instruction:\n    ");
       DEBUG(LoadI->print(dbgs()));
       DEBUG(dbgs() << "\n");
@@ -831,6 +832,8 @@ AArch64LoadStoreOpt::promoteLoadFromStor
               .addImm(Imms);
     }
   }
+  StoreI->clearRegisterKills(StRt, TRI);
+
   (void)BitExtMI;
 
   DEBUG(dbgs() << "Promoting load by replacing :\n    ");

Modified: llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.h?rev=290014&r1=290013&r2=290014&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.h (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.h Fri Dec 16 17:55:43 2016
@@ -95,6 +95,10 @@ public:
 
   unsigned getRegPressureLimit(const TargetRegisterClass *RC,
                                MachineFunction &MF) const override;
+
+  bool trackLivenessAfterRegAlloc(const MachineFunction&) const override {
+    return true;
+  }
 };
 
 } // end namespace llvm

Modified: llvm/trunk/test/CodeGen/AArch64/ldst-opt-dbg-limit.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/ldst-opt-dbg-limit.mir?rev=290014&r1=290013&r2=290014&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/ldst-opt-dbg-limit.mir (original)
+++ llvm/trunk/test/CodeGen/AArch64/ldst-opt-dbg-limit.mir Fri Dec 16 17:55:43 2016
@@ -28,7 +28,7 @@
 name:            promote-load-from-store
 alignment:       2
 exposesReturnsTwice: false
-tracksRegLiveness: false
+tracksRegLiveness: true
 liveins:         
   - { reg: '%x0' }
   - { reg: '%w1' }
@@ -48,7 +48,7 @@ frameInfo:
   hasMustTailInVarArgFunc: false
 body:             |
   bb.0 (%ir-block.0):
-    liveins: %w1, %x0
+    liveins: %w1, %x0, %lr
   
     STRWui killed %w1, %x0, 0 :: (store 4 into %ir.dst)
     CFI_INSTRUCTION 0
@@ -76,13 +76,13 @@ body:             |
 
 ...
 # CHECK-LABEL: name:            promote-load-from-store
-# CHECK: STRWui killed %w1
+# CHECK: STRWui %w1
 # CHECK: UBFMWri %w1
 ---
 name:            store-pair
 alignment:       2
 exposesReturnsTwice: false
-tracksRegLiveness: false
+tracksRegLiveness: true
 liveins:         
   - { reg: '%x0' }
   - { reg: '%w1' }
@@ -102,7 +102,7 @@ frameInfo:
   hasMustTailInVarArgFunc: false
 body:             |
   bb.0 (%ir-block.0):
-    liveins: %w1, %x0
+    liveins: %w1, %x0, %lr
   
     STRWui %w1, %x0, 0 :: (store 4 into %ir.dst01)
     CFI_INSTRUCTION 0

Modified: llvm/trunk/test/CodeGen/AArch64/movimm-wzr.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/movimm-wzr.mir?rev=290014&r1=290013&r2=290014&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/movimm-wzr.mir (original)
+++ llvm/trunk/test/CodeGen/AArch64/movimm-wzr.mir Fri Dec 16 17:55:43 2016
@@ -39,4 +39,4 @@ body:             |
 ...
 
 # CHECK: bb.0
-# CHECK-NEXT: RET %lr
+# CHECK-NEXT: RET undef %lr