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[SCEV] Revert bailout added in r75511.

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Summary:
With the introduction of MarkPendingLoopPredicates in r157092, I don't
think the bailout is needed anymore.

Reviewers: atrick, nicholas

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8624

llvm-svn: 233296
This commit is contained in:
Sanjoy Das 2015-03-26 17:28:26 +00:00
parent 6b16639733
commit f1fd8e6a14
2 changed files with 56 additions and 12 deletions
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23
lib/Analysis/ScalarEvolution.cpp
View File

@ -6793,15 +6793,6 @@ bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred,
ICmpInst *ICI = dyn_cast<ICmpInst>(FoundCondValue);
if (!ICI) return false;
// Bail if the ICmp's operands' types are wider than the needed type
// before attempting to call getSCEV on them. This avoids infinite
// recursion, since the analysis of widening casts can require loop
// exit condition information for overflow checking, which would
// lead back here.
if (getTypeSizeInBits(LHS->getType()) <
getTypeSizeInBits(ICI->getOperand(0)->getType()))
return false;
// Now that we found a conditional branch that dominates the loop or controls
// the loop latch. Check to see if it is the comparison we are looking for.
ICmpInst::Predicate FoundPred;
@ -6813,9 +6804,17 @@ bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred,
const SCEV *FoundLHS = getSCEV(ICI->getOperand(0));
const SCEV *FoundRHS = getSCEV(ICI->getOperand(1));
// Balance the types. The case where FoundLHS' type is wider than
// LHS' type is checked for above.
if (getTypeSizeInBits(LHS->getType()) >
// Balance the types.
if (getTypeSizeInBits(LHS->getType()) <
getTypeSizeInBits(FoundLHS->getType())) {
if (CmpInst::isSigned(Pred)) {
LHS = getSignExtendExpr(LHS, FoundLHS->getType());
RHS = getSignExtendExpr(RHS, FoundLHS->getType());
} else {
LHS = getZeroExtendExpr(LHS, FoundLHS->getType());
RHS = getZeroExtendExpr(RHS, FoundLHS->getType());
}
} else if (getTypeSizeInBits(LHS->getType()) >
getTypeSizeInBits(FoundLHS->getType())) {
if (CmpInst::isSigned(FoundPred)) {
FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType());

45
test/Analysis/ScalarEvolution/ext-antecedent.ll Normal file
View File

@ -0,0 +1,45 @@
; RUN: opt -S -indvars < %s | FileCheck %s
declare void @use(i1)
define void @sext_condition(i8 %t) {
; CHECK-LABEL: sext_condition
entry:
%st = sext i8 %t to i16
%ecmp = icmp slt i16 %st, 42
br i1 %ecmp, label %loop, label %exit
loop:
; CHECK-LABEL: loop
%idx = phi i8 [ %t, %entry ], [ %idx.inc, %loop ]
%idx.inc = add i8 %idx, 1
%c = icmp slt i8 %idx, 42
; CHECK: call void @use(i1 true)
call void @use(i1 %c)
%be = icmp slt i8 %idx.inc, 42
br i1 %be, label %loop, label %exit
exit:
ret void
}
define void @zext_condition(i8 %t) {
; CHECK-LABEL: zext_condition
entry:
%st = zext i8 %t to i16
%ecmp = icmp ult i16 %st, 42
br i1 %ecmp, label %loop, label %exit
loop:
; CHECK-LABEL: loop
%idx = phi i8 [ %t, %entry ], [ %idx.inc, %loop ]
%idx.inc = add i8 %idx, 1
%c = icmp ult i8 %idx, 42
; CHECK: call void @use(i1 true)
call void @use(i1 %c)
%be = icmp ult i8 %idx.inc, 42
br i1 %be, label %loop, label %exit
exit:
ret void
}