[llvm] r251620 - [MachineVerifier] Analyze MachineMemOperands for mem-to-mem moves.

[Jonas Paulsson via llvm-commits]

Author: jonpa
Date: Thu Oct 29 03:28:35 2015
New Revision: 251620

URL: http://llvm.org/viewvc/llvm-project?rev=251620&view=rev
Log:
[MachineVerifier] Analyze MachineMemOperands for mem-to-mem moves.

Since the verifier will give false reports if it incorrectly thinks MI is
loading or storing using an FI, it is necessary to scan memoperands and
find out how the FI is used in the instruction. This should be relatively
rare.

Needed to make CodeGen/SystemZ/spill-01.ll pass, which now runs with this flag.

Reviewed by Quentin Colombet.

Modified:
    llvm/trunk/lib/CodeGen/MachineVerifier.cpp
    llvm/trunk/test/CodeGen/SystemZ/spill-01.ll

Modified: llvm/trunk/lib/CodeGen/MachineVerifier.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineVerifier.cpp?rev=251620&r1=251619&r2=251620&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineVerifier.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineVerifier.cpp Thu Oct 29 03:28:35 2015
@@ -992,15 +992,34 @@ MachineVerifier::visitMachineOperand(con
   case MachineOperand::MO_FrameIndex:
     if (LiveStks && LiveStks->hasInterval(MO->getIndex()) &&
         LiveInts && !LiveInts->isNotInMIMap(MI)) {
-      LiveInterval &LI = LiveStks->getInterval(MO->getIndex());
+      int FI = MO->getIndex();
+      LiveInterval &LI = LiveStks->getInterval(FI);
       SlotIndex Idx = LiveInts->getInstructionIndex(MI);
 
-      // For a memory-to-memory move, we don't know if MI is using
-      // this frame index for loading or storing, so check for
-      // liveness at reg-slot only in the simple load case.
       bool stores = MI->mayStore();
-      bool simpleLoad = (MI->mayLoad() && !stores);
-      if (simpleLoad && !LI.liveAt(Idx.getRegSlot(true))) {
+      bool loads = MI->mayLoad();
+      // For a memory-to-memory move, we need to check if the frame
+      // index is used for storing or loading, by inspecting the
+      // memory operands.
+      if (stores && loads) {
+        for (auto *MMO : MI->memoperands()) {
+          const PseudoSourceValue *PSV = MMO->getPseudoValue();
+          if (PSV == nullptr) continue;
+          const FixedStackPseudoSourceValue *Value =
+            dyn_cast<FixedStackPseudoSourceValue>(PSV);
+          if (Value == nullptr) continue;
+          if (Value->getFrameIndex() != FI) continue;
+
+          if (MMO->isStore())
+            loads = false;
+          else
+            stores = false;
+          break;
+        }
+        if (loads == stores)
+          report("Missing fixed stack memoperand.", MI);
+      }
+      if (loads && !LI.liveAt(Idx.getRegSlot(true))) {
         report("Instruction loads from dead spill slot", MO, MONum);
         errs() << "Live stack: " << LI << '\n';
       }

Modified: llvm/trunk/test/CodeGen/SystemZ/spill-01.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/SystemZ/spill-01.ll?rev=251620&r1=251619&r2=251620&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/SystemZ/spill-01.ll (original)
+++ llvm/trunk/test/CodeGen/SystemZ/spill-01.ll Thu Oct 29 03:28:35 2015
@@ -1,7 +1,7 @@
 ; Test spilling using MVC.  The tests here assume z10 register pressure,
 ; without the high words being available.
 ;
-; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z10 | FileCheck %s
+; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z10 -verify-machineinstrs | FileCheck %s
 
 declare void @foo()