[llvm-commits] [llvm] r39893 - in /llvm/trunk: include/llvm/Analysis/ScalarEvolutionExpressions.h lib/Analysis/ScalarEvolution.cpp test/Analysis/ScalarEvolution/2007-07-15-NegativeStride.ll
Nick Lewycky
nicholas at mxc.ca
Sun Jul 15 19:08:01 PDT 2007
Author: nicholas
Date: Sun Jul 15 21:08:00 2007
New Revision: 39893
URL: http://llvm.org/viewvc/llvm-project?rev=39893&view=rev
Log:
Handle decrementing loops properly. Fixes PR1533.
Always pass the constant as the second parameter to HowManyLessThans.
Remove obsolete "isSigned" parameter.
Added:
llvm/trunk/test/Analysis/ScalarEvolution/2007-07-15-NegativeStride.ll
Modified:
llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpressions.h
llvm/trunk/lib/Analysis/ScalarEvolution.cpp
Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpressions.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpressions.h?rev=39893&r1=39892&r2=39893&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpressions.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpressions.h Sun Jul 15 21:08:00 2007
@@ -475,10 +475,8 @@
/// looking at this is that it returns the first iteration number where the
/// value is not in the condition, thus computing the exit count. If the
/// iteration count can't be computed, an instance of SCEVCouldNotCompute is
- /// returned. The isSigned parameter indicates whether the ConstantRange
- /// should be treated as signed or unsigned.
- SCEVHandle getNumIterationsInRange(ConstantRange Range,
- bool isSigned) const;
+ /// returned.
+ SCEVHandle getNumIterationsInRange(ConstantRange Range) const;
SCEVHandle replaceSymbolicValuesWithConcrete(const SCEVHandle &Sym,
const SCEVHandle &Conc) const;
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=39893&r1=39892&r2=39893&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Sun Jul 15 21:08:00 2007
@@ -1671,8 +1671,7 @@
ConstantRange CompRange(
ICmpInst::makeConstantRange(Cond, CompVal->getValue()));
- SCEVHandle Ret = AddRec->getNumIterationsInRange(CompRange,
- false /*Always treat as unsigned range*/);
+ SCEVHandle Ret = AddRec->getNumIterationsInRange(CompRange);
if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
}
}
@@ -1696,7 +1695,8 @@
break;
}
case ICmpInst::ICMP_SGT: {
- SCEVHandle TC = HowManyLessThans(RHS, LHS, L);
+ SCEVHandle TC = HowManyLessThans(SCEV::getNegativeSCEV(LHS),
+ SCEV::getNegativeSCEV(RHS), L);
if (!isa<SCEVCouldNotCompute>(TC)) return TC;
break;
}
@@ -2406,8 +2406,7 @@
/// this is that it returns the first iteration number where the value is not in
/// the condition, thus computing the exit count. If the iteration count can't
/// be computed, an instance of SCEVCouldNotCompute is returned.
-SCEVHandle SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range,
- bool isSigned) const {
+SCEVHandle SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range) const {
if (Range.isFullSet()) // Infinite loop.
return new SCEVCouldNotCompute();
@@ -2419,7 +2418,7 @@
SCEVHandle Shifted = SCEVAddRecExpr::get(Operands, getLoop());
if (SCEVAddRecExpr *ShiftedAddRec = dyn_cast<SCEVAddRecExpr>(Shifted))
return ShiftedAddRec->getNumIterationsInRange(
- Range.subtract(SC->getValue()->getValue()),isSigned);
+ Range.subtract(SC->getValue()->getValue()));
// This is strange and shouldn't happen.
return new SCEVCouldNotCompute();
}
@@ -2443,17 +2442,16 @@
// If this is an affine expression then we have this situation:
// Solve {0,+,A} in Range === Ax in Range
- // Since we know that zero is in the range, we know that the upper value of
- // the range must be the first possible exit value. Also note that we
- // already checked for a full range.
- const APInt &Upper = Range.getUpper();
- APInt A = cast<SCEVConstant>(getOperand(1))->getValue()->getValue();
+ // We know that zero is in the range. If A is positive then we know that
+ // the upper value of the range must be the first possible exit value.
+ // If A is negative then the lower of the range is the last possible loop
+ // value. Also note that we already checked for a full range.
APInt One(getBitWidth(),1);
+ APInt A = cast<SCEVConstant>(getOperand(1))->getValue()->getValue();
+ APInt End = A.sge(One) ? (Range.getUpper() - One) : Range.getLower();
- // The exit value should be (Upper+A-1)/A.
- APInt ExitVal(Upper);
- if (A != One)
- ExitVal = (Upper + A - One).sdiv(A);
+ // The exit value should be (End+A)/A.
+ APInt ExitVal = (End + A).sdiv(A);
ConstantInt *ExitValue = ConstantInt::get(ExitVal);
// Evaluate at the exit value. If we really did fall out of the valid
Added: llvm/trunk/test/Analysis/ScalarEvolution/2007-07-15-NegativeStride.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/2007-07-15-NegativeStride.ll?rev=39893&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/2007-07-15-NegativeStride.ll (added)
+++ llvm/trunk/test/Analysis/ScalarEvolution/2007-07-15-NegativeStride.ll Sun Jul 15 21:08:00 2007
@@ -0,0 +1,20 @@
+; RUN: llvm-as < %s | opt -analyze -scalar-evolution 2>&1 | grep "Loop bb: 100 iterations"
+; PR1533
+
+ at array = weak global [101 x i32] zeroinitializer, align 32 ; <[100 x i32]*> [#uses=1]
+
+define void @loop(i32 %x) {
+entry:
+ br label %bb
+
+bb: ; preds = %bb, %entry
+ %i.01.0 = phi i32 [ 100, %entry ], [ %tmp4, %bb ] ; <i32> [#uses=2]
+ %tmp1 = getelementptr [101 x i32]* @array, i32 0, i32 %i.01.0 ; <i32*> [#uses=1]
+ store i32 %x, i32* %tmp1
+ %tmp4 = add i32 %i.01.0, -1 ; <i32> [#uses=2]
+ %tmp7 = icmp sgt i32 %tmp4, -1 ; <i1> [#uses=1]
+ br i1 %tmp7, label %bb, label %return
+
+return: ; preds = %bb
+ ret void
+}
More information about the llvm-commits
mailing list