[llvm-commits] [llvm] r112988 - /llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Fri Sep  3 13:36:56 2010
New Revision: 112988

URL: http://llvm.org/viewvc/llvm-project?rev=112988&view=rev
Log:
VirtRegRewriter checks for early clobbers before it reuses an available stack
slot.

Teach it to also check for early clobbered aliases, and early clobber operands
following the current operand.

This fixes the miscompilation in PR8044 where EC registers eax and ecx were
being used for inputs.

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

Modified: llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp?rev=112988&r1=112987&r2=112988&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp (original)
+++ llvm/trunk/lib/CodeGen/VirtRegRewriter.cpp Fri Sep  3 13:36:56 2010
@@ -2027,14 +2027,16 @@
           CanReuse = !ReusedOperands.isClobbered(PhysReg) &&
             Spills.canClobberPhysReg(PhysReg);
         }
-        // If this is an asm, and PhysReg is used elsewhere as an earlyclobber
-        // operand, we can't also use it as an input.  (Outputs always come
-        // before inputs, so we can stop looking at i.)
+        // If this is an asm, and a PhysReg alias is used elsewhere as an
+        // earlyclobber operand, we can't also use it as an input.
         if (MI.isInlineAsm()) {
-          for (unsigned k=0; k<i; ++k) {
+          for (unsigned k = 0, e = MI.getNumOperands(); k != e; ++k) {
             MachineOperand &MOk = MI.getOperand(k);
-            if (MOk.isReg() && MOk.getReg()==PhysReg && MOk.isEarlyClobber()) {
+            if (MOk.isReg() && MOk.isEarlyClobber() &&
+                TRI->regsOverlap(MOk.getReg(), PhysReg)) {
               CanReuse = false;
+              DEBUG(dbgs() << "Not reusing physreg " << TRI->getName(PhysReg)
+                           << " for vreg" << VirtReg << ": " << MOk << '\n');
               break;
             }
           }