[llvm] r268412 - [ImplicitNullChecks] Account for implicit-defs as well when updating the liveness.

[Quentin Colombet via llvm-commits]

Author: qcolombet
Date: Tue May  3 13:09:06 2016
New Revision: 268412

URL: http://llvm.org/viewvc/llvm-project?rev=268412&view=rev
Log:
[ImplicitNullChecks] Account for implicit-defs as well when updating the liveness.

The replaced load may have implicit-defs and those defs may be used
in the block of the original load. Make sure to update the liveness
accordingly.

This is a generalization of r267817.

Modified:
    llvm/trunk/lib/CodeGen/ImplicitNullChecks.cpp
    llvm/trunk/test/CodeGen/X86/implicit-null-check.ll

Modified: llvm/trunk/lib/CodeGen/ImplicitNullChecks.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ImplicitNullChecks.cpp?rev=268412&r1=268411&r2=268412&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/ImplicitNullChecks.cpp (original)
+++ llvm/trunk/lib/CodeGen/ImplicitNullChecks.cpp Tue May  3 13:09:06 2016
@@ -398,13 +398,18 @@ void ImplicitNullChecks::rewriteNullChec
     // control flow, we've just made it implicit.
     MachineInstr *FaultingLoad =
         insertFaultingLoad(NC.MemOperation, NC.CheckBlock, NC.NullSucc);
-    // Now the value of the MemOperation, if any, is live-in of block
-    // of MemOperation.
-    unsigned Reg = FaultingLoad->getOperand(0).getReg();
-    if (Reg) {
-      MachineBasicBlock *MBB = NC.MemOperation->getParent();
-      if (!MBB->isLiveIn(Reg))
-        MBB->addLiveIn(Reg);
+    // Now the values defined by MemOperation, if any, are live-in of
+    // the block of MemOperation.
+    // The original load operation may define implicit-defs alongside
+    // the loaded value.
+    MachineBasicBlock *MBB = NC.MemOperation->getParent();
+    for (const MachineOperand &MO : FaultingLoad->operands()) {
+      if (!MO.isReg() || !MO.isDef())
+        continue;
+      unsigned Reg = MO.getReg();
+      if (!Reg || MBB->isLiveIn(Reg))
+        continue;
+      MBB->addLiveIn(Reg);
     }
     NC.MemOperation->eraseFromParent();
     NC.CheckOperation->eraseFromParent();

Modified: llvm/trunk/test/CodeGen/X86/implicit-null-check.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/implicit-null-check.ll?rev=268412&r1=268411&r2=268412&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/implicit-null-check.ll (original)
+++ llvm/trunk/test/CodeGen/X86/implicit-null-check.ll Tue May  3 13:09:06 2016
@@ -1,4 +1,4 @@
-; RUN: llc -O3 -mtriple=x86_64-apple-macosx -enable-implicit-null-checks < %s | FileCheck %s
+; RUN: llc -verify-machineinstrs -O3 -mtriple=x86_64-apple-macosx -enable-implicit-null-checks < %s | FileCheck %s
 
 ; RUN: llc < %s -mtriple=x86_64-apple-macosx -enable-implicit-null-checks \
 ; RUN:    | llvm-mc -triple x86_64-apple-macosx -filetype=obj -o - \