Revert "[TargetRegisterInfo] Refactor the code to use BitMaskClassIterator."

This reverts commit r265734.
Looks like ASan is not happy about it.
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/11741

Looking.

llvm-svn: 265755

1 files changed, 12 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/TargetRegisterInfo.cpp b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
index e1d90cb913e..fc88629b5c8 100644
--- a/llvm/lib/CodeGen/TargetRegisterInfo.cpp
+++ b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
@@ -112,11 +112,18 @@ TargetRegisterInfo::getAllocatableClass(const TargetRegisterClass *RC) const {
   if (!RC || RC->isAllocatable())
     return RC;
 
-  for (BitMaskClassIterator It(RC->getSubClassMask(), *this); It.isValid();
-       ++It) {
-    const TargetRegisterClass *SubRC = getRegClass(It.getID());
-    if (SubRC->isAllocatable())
-      return SubRC;
+  const unsigned *SubClass = RC->getSubClassMask();
+  for (unsigned Base = 0, BaseE = getNumRegClasses();
+       Base < BaseE; Base += 32) {
+    unsigned Idx = Base;
+    for (unsigned Mask = *SubClass++; Mask; Mask >>= 1) {
+      unsigned Offset = countTrailingZeros(Mask);
+      const TargetRegisterClass *SubRC = getRegClass(Idx + Offset);
+      if (SubRC->isAllocatable())
+        return SubRC;
+      Mask >>= Offset;
+      Idx += Offset + 1;
+    }
   }
   return nullptr;
 }