[llvm-commits] [llvm] r157651 - /llvm/trunk/include/llvm/Target/TargetRegisterInfo.h

[Jakob Stoklund Olesen]

Author: stoklund
Date: Tue May 29 18:40:02 2012
New Revision: 157651

URL: http://llvm.org/viewvc/llvm-project?rev=157651&view=rev
Log:
Use MCRegUnitIterator to compute regsOverlap().

The register unit lists are typically much shorter than the register
overlap lists, and the backing table for register units has better cache
locality because it is smaller.

This makes llc about 0.5% faster. The regsOverlap() function isn't that hot.

Modified:
    llvm/trunk/include/llvm/Target/TargetRegisterInfo.h

Modified: llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetRegisterInfo.h?rev=157651&r1=157650&r2=157651&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetRegisterInfo.h (original)
+++ llvm/trunk/include/llvm/Target/TargetRegisterInfo.h Tue May 29 18:40:02 2012
@@ -337,9 +337,15 @@
     if (regA == regB) return true;
     if (isVirtualRegister(regA) || isVirtualRegister(regB))
       return false;
-    for (const uint16_t *regList = getOverlaps(regA)+1; *regList; ++regList) {
-      if (*regList == regB) return true;
-    }
+
+    // Regunits are numerically ordered. Find a common unit.
+    MCRegUnitIterator RUA(regA, this);
+    MCRegUnitIterator RUB(regB, this);
+    do {
+      if (*RUA == *RUB) return true;
+      if (*RUA < *RUB) ++RUA;
+      else             ++RUB;
+    } while (RUA.isValid() && RUB.isValid());
     return false;
   }