[llvm-commits] [llvm] r73717 - /llvm/trunk/lib/Analysis/ScalarEvolution.cpp

[Dan Gohman]

Author: djg
Date: Thu Jun 18 15:21:07 2009
New Revision: 73717

URL: http://llvm.org/viewvc/llvm-project?rev=73717&view=rev
Log:
Recognize n != 0 ? n : 1 as umax(n, 1). Previously only ULT/UGT/ULE/UGE
comparisons were recognized for umax, but instcombine canonicalizes
unsigned comparisons with zero to this simpler form.

Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=73717&r1=73716&r2=73717&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Thu Jun 18 15:21:07 2009
@@ -2580,6 +2580,24 @@
           return getNotSCEV(getUMaxExpr(getNotSCEV(getSCEV(LHS)),
                                         getNotSCEV(getSCEV(RHS))));
         break;
+      case ICmpInst::ICMP_NE:
+        // n != 0 ? n : 1  ->  umax(n, 1)
+        if (LHS == U->getOperand(1) &&
+            isa<ConstantInt>(U->getOperand(2)) &&
+            cast<ConstantInt>(U->getOperand(2))->isOne() &&
+            isa<ConstantInt>(RHS) &&
+            cast<ConstantInt>(RHS)->isZero())
+          return getUMaxExpr(getSCEV(LHS), getSCEV(U->getOperand(2)));
+        break;
+      case ICmpInst::ICMP_EQ:
+        // n == 0 ? 1 : n  ->  umax(n, 1)
+        if (LHS == U->getOperand(2) &&
+            isa<ConstantInt>(U->getOperand(1)) &&
+            cast<ConstantInt>(U->getOperand(1))->isOne() &&
+            isa<ConstantInt>(RHS) &&
+            cast<ConstantInt>(RHS)->isZero())
+          return getUMaxExpr(getSCEV(LHS), getSCEV(U->getOperand(1)));
+        break;
       default:
         break;
       }