[llvm-commits] [llvm] r97046 - /llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Wed Feb 24 12:57:08 2010
New Revision: 97046

URL: http://llvm.org/viewvc/llvm-project?rev=97046&view=rev
Log:
Stay away from str <undef> in ARMLoadStoreOpt. This pass does not understand
<undef> operands, and can cause scavenger failures when it translates
<kill,undef> to <kill>.

Modified:
    llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp

Modified: llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp?rev=97046&r1=97045&r2=97046&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMLoadStoreOptimizer.cpp Wed Feb 24 12:57:08 2010
@@ -748,11 +748,19 @@
     if (MMO->isVolatile())
       return false;
 
-    // Unaligned ldr/str is emulated by some kernels, but unaligned ldm/stm is not.
+    // Unaligned ldr/str is emulated by some kernels, but unaligned ldm/stm is
+    // not.
     if (MMO->getAlignment() < 4)
       return false;
   }
 
+  // str <undef> could probably be eliminated entirely, but for now we just want
+  // to avoid making a mess of it.
+  // FIXME: Use str <undef> as a wildcard to enable better stm folding.
+  if (MI->getNumOperands() > 0 && MI->getOperand(0).isReg() &&
+      MI->getOperand(0).isUndef())
+    return false;
+
   int Opcode = MI->getOpcode();
   switch (Opcode) {
   default: break;