Fix a bug in the A57FPLoadBalancing register tracking/scavenger.

The code in AArch64A57FPLoadBalancing::scavengeRegister() to handle dead defs
was not correctly handling aliased registers.  E.g. if the dead def was of D2,
then S2 was not being marked as unavailable, so it could potentially be used
across a live-range in which it would be clobbered.

Patch by Geoff Berry <gberry@codeaurora.org>!
Phabricator: http://reviews.llvm.org/D10900

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241449 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp b/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp
index bffd9e6e8c76afec57e83bd80995772c1e66c0a8..9d6dbd641a1628a71e4bbd03d00a4aff26714a76 100644 (file)
--- a/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp
+++ b/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp
@@ -510,9 +510,17 @@ int AArch64A57FPLoadBalancing::scavengeRegister(Chain *G, Color C,
       if (J.isRegMask())
         AvailableRegs.clearBitsNotInMask(J.getRegMask());
 
-      if (J.isReg() && J.isDef() && AvailableRegs[J.getReg()]) {
-        assert(J.isDead() && "Non-dead def should have been removed by now!");
-        AvailableRegs.reset(J.getReg());
+      if (J.isReg() && J.isDef()) {
+        MCRegAliasIterator AI(J.getReg(), TRI, /*IncludeSelf=*/true);
+        if (J.isDead())
+          for (; AI.isValid(); ++AI)
+            AvailableRegs.reset(*AI);
+#ifndef NDEBUG
+        else
+          for (; AI.isValid(); ++AI)
+            assert(!AvailableRegs[*AI] &&
+                   "Non-dead def should have been removed by now!");
+#endif
       }
     }
   }