commit 459d729bc4d4b7b8c92dc5bb6412b3d99526ac08
author Eli Friedman <eli.friedman@gmail.com> Sat May 09 12:32:42 2009 +0000
committer Eli Friedman <eli.friedman@gmail.com> Sat May 09 12:32:42 2009 +0000
tree 9a651fda61ff46e13b4c756dc35b6c4bffd31bd6
parent 92195737400123e29156c4901ee7e99742514db5

Allow scalar evolution to compute iteration counts for loops with a 
pointer-based condition.  This fixes PR3171.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71354 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/ScalarEvolution.cpp

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index e65cdd2..107a7c4 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2372,10 +2372,8 @@
   
   ICmpInst *ExitCond = dyn_cast<ICmpInst>(ExitBr->getCondition());
 
-  // If it's not an integer comparison then compute it the hard way. 
-  // Note that ICmpInst deals with pointer comparisons too so we must check
-  // the type of the operand.
-  if (ExitCond == 0 || isa<PointerType>(ExitCond->getOperand(0)->getType()))
+  // If it's not an integer or pointer comparison then compute it the hard way.
+  if (ExitCond == 0)
     return ComputeBackedgeTakenCountExhaustively(L, ExitBr->getCondition(),
                                           ExitBr->getSuccessor(0) == ExitBlock);
 
@@ -2416,21 +2414,12 @@
   if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
     if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
       if (AddRec->getLoop() == L) {
-        // Form the comparison range using the constant of the correct type so
-        // that the ConstantRange class knows to do a signed or unsigned
-        // comparison.
-        ConstantInt *CompVal = RHSC->getValue();
-        const Type *RealTy = ExitCond->getOperand(0)->getType();
-        CompVal = dyn_cast<ConstantInt>(
-          ConstantExpr::getBitCast(CompVal, RealTy));
-        if (CompVal) {
-          // Form the constant range.
-          ConstantRange CompRange(
-              ICmpInst::makeConstantRange(Cond, CompVal->getValue()));
+        // Form the constant range.
+        ConstantRange CompRange(
+            ICmpInst::makeConstantRange(Cond, RHSC->getValue()->getValue()));
 
-          SCEVHandle Ret = AddRec->getNumIterationsInRange(CompRange, *this);
-          if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
-        }
+        SCEVHandle Ret = AddRec->getNumIterationsInRange(CompRange, *this);
+        if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
       }
 
   switch (Cond) {