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 8f1cce6..99fc6c9 100644
--- a/lib/CodeGen/RegAllocLocal.cpp
+++ b/lib/CodeGen/RegAllocLocal.cpp
@@ -368,7 +368,7 @@
// 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;
}