[polly] r190384 - TempScopInfo: Microoptimize constant conditions

[Tobias Grosser]

Author: grosser
Date: Mon Sep  9 23:47:19 2013
New Revision: 190384

URL: http://llvm.org/viewvc/llvm-project?rev=190384&view=rev
Log:
TempScopInfo: Microoptimize constant conditions

Use 0 >= 1 instead of 0 != 0 to represent 'false'. This might be slightly more
efficient as isl may create a union of sets for 0 != 0, whereas this is never
needed for the expression 0 >= 1.

Contributed-by: Alexandre Isoard <alexandre.isoard at gmail.com>

Modified:
    polly/trunk/lib/Analysis/TempScopInfo.cpp

Modified: polly/trunk/lib/Analysis/TempScopInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/TempScopInfo.cpp?rev=190384&r1=190383&r2=190384&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/TempScopInfo.cpp (original)
+++ polly/trunk/lib/Analysis/TempScopInfo.cpp Mon Sep  9 23:47:19 2013
@@ -230,14 +230,15 @@ void TempScopInfo::buildLoopBounds(TempS
 void TempScopInfo::buildAffineCondition(Value &V, bool inverted,
                                         Comparison **Comp) const {
   if (ConstantInt *C = dyn_cast<ConstantInt>(&V)) {
-    // If this is always true condition, we will create 0 == 0,
-    // otherwise we will create 0 != 0.
+    // If this is always true condition, we will create 0 <= 1,
+    // otherwise we will create 0 >= 1.
     const SCEV *LHS = SE->getConstant(C->getType(), 0);
+    const SCEV *RHS = SE->getConstant(C->getType(), 1);
 
     if (C->isOne() == inverted)
-      *Comp = new Comparison(LHS, LHS, ICmpInst::ICMP_NE);
+      *Comp = new Comparison(LHS, RHS, ICmpInst::ICMP_SLE);
     else
-      *Comp = new Comparison(LHS, LHS, ICmpInst::ICMP_EQ);
+      *Comp = new Comparison(LHS, RHS, ICmpInst::ICMP_SGE);
 
     return;
   }