[llvm-commits] [llvm] r127857 - /llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Thu Mar 17 22:06:04 2011
New Revision: 127857

URL: http://llvm.org/viewvc/llvm-project?rev=127857&view=rev
Log:
Accept instructions that read undefined values.

This is not supposed to happen, but I have seen the x86 rematter getting
confused when rematerializing partial redefs.

Modified:
    llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp

Modified: llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp?rev=127857&r1=127856&r2=127857&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp (original)
+++ llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp Thu Mar 17 22:06:04 2011
@@ -761,7 +761,15 @@
       continue;
     SlotIndex Idx = getInstructionIndex(UseMI).getUseIndex();
     VNInfo *VNI = li->getVNInfoAt(Idx);
-    assert(VNI && "Live interval not live into reading instruction");
+    if (!VNI) {
+      // This shouldn't happen: readsVirtualRegister returns true, but there is
+      // no live value. It is likely caused by a target getting <undef> flags
+      // wrong.
+      DEBUG(dbgs() << Idx << '\t' << *UseMI
+                   << "Warning: Instr claims to read non-existent value in "
+                    << *li << '\n');
+      continue;
+    }
     if (VNI->def == Idx) {
       // Special case: An early-clobber tied operand reads and writes the
       // register one slot early.