[llvm] r244265 - [IndVars] Fix PR24356.
Sanjoy Das via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 6 13:43:41 PDT 2015
Author: sanjoy
Date: Thu Aug 6 15:43:41 2015
New Revision: 244265
URL: http://llvm.org/viewvc/llvm-project?rev=244265&view=rev
Log:
[IndVars] Fix PR24356.
Unsigned predicates increase or decrease agnostic of the signs of their
increments.
Added:
llvm/trunk/test/Transforms/IndVarSimplify/pr24356.ll
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=244265&r1=244264&r2=244265&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Thu Aug 6 15:43:41 2015
@@ -6721,8 +6721,16 @@ bool ScalarEvolution::isMonotonicPredica
bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS,
ICmpInst::Predicate Pred,
bool &Increasing) {
- SCEV::NoWrapFlags FlagsRequired = SCEV::FlagAnyWrap;
- bool IncreasingOnNonNegativeStep = false;
+
+ // A zero step value for LHS means the induction variable is essentially a
+ // loop invariant value. We don't really depend on the predicate actually
+ // flipping from false to true (for increasing predicates, and the other way
+ // around for decreasing predicates), all we care about is that *if* the
+ // predicate changes then it only changes from false to true.
+ //
+ // A zero step value in itself is not very useful, but there may be places
+ // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be
+ // as general as possible.
switch (Pred) {
default:
@@ -6730,53 +6738,39 @@ bool ScalarEvolution::isMonotonicPredica
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
- FlagsRequired = SCEV::FlagNUW;
- IncreasingOnNonNegativeStep = true;
- break;
-
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
- FlagsRequired = SCEV::FlagNUW;
- IncreasingOnNonNegativeStep = false;
- break;
+ if (!LHS->getNoWrapFlags(SCEV::FlagNUW))
+ return false;
+
+ Increasing = Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE;
+ return true;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
- FlagsRequired = SCEV::FlagNSW;
- IncreasingOnNonNegativeStep = true;
- break;
-
case ICmpInst::ICMP_SLT:
- case ICmpInst::ICMP_SLE:
- FlagsRequired = SCEV::FlagNSW;
- IncreasingOnNonNegativeStep = false;
- break;
- }
+ case ICmpInst::ICMP_SLE: {
+ if (!LHS->getNoWrapFlags(SCEV::FlagNSW))
+ return false;
+
+ const SCEV *Step = LHS->getStepRecurrence(*this);
+
+ if (isKnownNonNegative(Step)) {
+ Increasing = Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE;
+ return true;
+ }
+
+ if (isKnownNonPositive(Step)) {
+ Increasing = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE;
+ return true;
+ }
- if (!LHS->getNoWrapFlags(FlagsRequired))
return false;
-
- // A zero step value for LHS means the induction variable is essentially a
- // loop invariant value. We don't really depend on the predicate actually
- // flipping from false to true (for increasing predicates, and the other way
- // around for decreasing predicates), all we care about is that *if* the
- // predicate changes then it only changes from false to true.
- //
- // A zero step value in itself is not very useful, but there may be places
- // where SCEV can prove X >= 0 but not prove X > 0, so it is helpful to be
- // as general as possible.
-
- if (isKnownNonNegative(LHS->getStepRecurrence(*this))) {
- Increasing = IncreasingOnNonNegativeStep;
- return true;
}
- if (isKnownNonPositive(LHS->getStepRecurrence(*this))) {
- Increasing = !IncreasingOnNonNegativeStep;
- return true;
}
- return false;
+ llvm_unreachable("switch has default clause!");
}
bool ScalarEvolution::isLoopInvariantPredicate(
Added: llvm/trunk/test/Transforms/IndVarSimplify/pr24356.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/pr24356.ll?rev=244265&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/pr24356.ll (added)
+++ llvm/trunk/test/Transforms/IndVarSimplify/pr24356.ll Thu Aug 6 15:43:41 2015
@@ -0,0 +1,63 @@
+; RUN: opt -S -indvars < %s | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.10.0"
+
+ at a = common global i32 0, align 4
+
+; Function Attrs: nounwind ssp uwtable
+define void @fn1() {
+; CHECK-LABEL: @fn1(
+bb:
+ br label %bb4.preheader
+
+bb4.preheader: ; preds = %bb, %bb16
+; CHECK-LABEL: bb4.preheader:
+ %b.03 = phi i8 [ 0, %bb ], [ %tmp17, %bb16 ]
+; CHECK: %tmp9 = icmp ugt i8 %b.03, 1
+; CHECK-NOT: %tmp9 = icmp ugt i8 0, 1
+
+ %tmp9 = icmp ugt i8 %b.03, 1
+ br i1 %tmp9, label %bb4.preheader.bb18.loopexit.split_crit_edge, label %bb4.preheader.bb4.preheader.split_crit_edge
+
+bb4.preheader.bb4.preheader.split_crit_edge: ; preds = %bb4.preheader
+ br label %bb4.preheader.split
+
+bb4.preheader.bb18.loopexit.split_crit_edge: ; preds = %bb4.preheader
+ store i32 0, i32* @a, align 4
+ br label %bb18.loopexit.split
+
+bb4.preheader.split: ; preds = %bb4.preheader.bb4.preheader.split_crit_edge
+ br label %bb7
+
+bb4: ; preds = %bb7
+ %tmp6 = icmp slt i32 %storemerge2, 0
+ br i1 %tmp6, label %bb7, label %bb16
+
+bb7: ; preds = %bb4.preheader.split, %bb4
+ %storemerge2 = phi i32 [ 0, %bb4.preheader.split ], [ %tmp14, %bb4 ]
+ %tmp14 = add nsw i32 %storemerge2, 1
+ br i1 false, label %bb18.loopexit, label %bb4
+
+bb16: ; preds = %bb4
+ %tmp14.lcssa5 = phi i32 [ %tmp14, %bb4 ]
+ %tmp17 = add i8 %b.03, -1
+ %tmp2 = icmp eq i8 %tmp17, -2
+ br i1 %tmp2, label %bb18.loopexit1, label %bb4.preheader
+
+bb18.loopexit: ; preds = %bb7
+ br label %bb18.loopexit.split
+
+bb18.loopexit.split: ; preds = %bb4.preheader.bb18.loopexit.split_crit_edge, %bb18.loopexit
+ br label %bb18
+
+bb18.loopexit1: ; preds = %bb16
+ %tmp14.lcssa5.lcssa = phi i32 [ %tmp14.lcssa5, %bb16 ]
+ store i32 %tmp14.lcssa5.lcssa, i32* @a, align 4
+ br label %bb18
+
+bb18: ; preds = %bb18.loopexit1, %bb18.loopexit.split
+ ret void
+}
+
+declare void @abort()
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