From: Evan Cheng <evan.cheng@apple.com>
Date: Fri, 22 Feb 2008 20:30:53 +0000 (+0000)
Subject: Really really bad local register allocator bug. On X86, it was never using ESI, EDI... 
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=bcfa1ca9768a0ff0e4c2935832287d7bb9921cec;p=oota-llvm.git

Really really bad local register allocator bug. On X86, it was never using ESI, EDI, and EBP because of a bug in RALocal::isPhysRegAvailable(). For example, when
it checks if ESI is available, it then looks at registers aliases to ESI. SIL is marked -2 (not allocatable) but isPhysRegAvailable() incorrectly assumes it is in use and returns false for ESI.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47499 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/RegAllocLocal.cpp b/lib/CodeGen/RegAllocLocal.cpp
index 8f1cce6f4fb..99fc6c9028a 100644
--- a/lib/CodeGen/RegAllocLocal.cpp
+++ b/lib/CodeGen/RegAllocLocal.cpp
@@ -368,7 +368,7 @@ bool RALocal::isPhysRegAvailable(unsigned PhysReg) const {
   // not free!
   for (const unsigned *AliasSet = TRI->getAliasSet(PhysReg);
        *AliasSet; ++AliasSet)
-    if (PhysRegsUsed[*AliasSet] != -1) // Aliased register in use?
+    if (PhysRegsUsed[*AliasSet] >= 0) // Aliased register in use?
       return false;                    // Can't use this reg then.
   return true;
 }