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[IndVars] Fix PR24356.

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Unsigned predicates increase or decrease agnostic of the signs of their
increments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244265 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjoy Das 2015-08-06 20:43:41 +00:00
parent 95d9915c5c
commit 93011351ea
2 changed files with 97 additions and 40 deletions
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74
lib/Analysis/ScalarEvolution.cpp
View File

@ -6721,40 +6721,6 @@ bool ScalarEvolution::isMonotonicPredicate(const SCEVAddRecExpr *LHS,
bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS,
ICmpInst::Predicate Pred,
bool &Increasing) {
SCEV::NoWrapFlags FlagsRequired = SCEV::FlagAnyWrap;
bool IncreasingOnNonNegativeStep = false;
switch (Pred) {
default:
return false; // Conservative answer
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;
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;
}
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
@ -6766,17 +6732,45 @@ bool ScalarEvolution::isMonotonicPredicateImpl(const SCEVAddRecExpr *LHS,
// 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;
switch (Pred) {
default:
return false; // Conservative answer
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
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:
case ICmpInst::ICMP_SLT:
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;
}
return false;
}
if (isKnownNonPositive(LHS->getStepRecurrence(*this))) {
Increasing = !IncreasingOnNonNegativeStep;
return true;
}
return false;
llvm_unreachable("switch has default clause!");
}
bool ScalarEvolution::isLoopInvariantPredicate(

63
test/Transforms/IndVarSimplify/pr24356.ll Normal file
View File

@ -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"
@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()