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Revert 260705, it appears to be causing pr26628 

The root issue appears to be a confusion around what makeNoWrapRegion actually does.   It seems likely we need two versions of this function with slightly different semantics.

llvm-svn: 260981
This commit is contained in:
Philip Reames 2016-02-16 17:14:30 +00:00
parent f8b8b7b5d0
commit 845435c86a
2 changed files with 0 additions and 76 deletions
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21
llvm/lib/Analysis/LazyValueInfo.cpp
View File

@ -961,27 +961,6 @@ bool LazyValueInfoCache::solveBlockValueConstantRange(LVILatticeVal &BBLV,
if (isa<BinaryOperator>(BBI)) {
if (ConstantInt *RHS = dyn_cast<ConstantInt>(BBI->getOperand(1))) {
RHSRange = ConstantRange(RHS->getValue());
// Try to use information about wrap flags to refine the range LHS can
// legally have. This is a slightly weird way to implement forward
// propagation over overflowing instructions, but it seems to be the only
// clean one we have. NOTE: Because we may have speculated the
// instruction, we can't constrain other uses of LHS even if they would
// seem to be equivelent control dependent with this op.
if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(BBI)) {
unsigned WrapKind = 0;
if (OBO->hasNoSignedWrap())
WrapKind |= OverflowingBinaryOperator::NoSignedWrap;
if (OBO->hasNoUnsignedWrap())
WrapKind |= OverflowingBinaryOperator::NoUnsignedWrap;
if (WrapKind) {
auto OpCode = static_cast<Instruction::BinaryOps>(BBI->getOpcode());
auto NoWrapCR =
ConstantRange::makeNoWrapRegion(OpCode, RHS->getValue(), WrapKind);
LHSRange = LHSRange.intersectWith(NoWrapCR);
}
}
} else {
BBLV.markOverdefined();
return true;

55
llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
View File

@ -199,58 +199,3 @@ out:
next:
ret void
}
; Can we use nsw in LVI to prove lack of overflow?
define i1 @add_nsw(i32 %s) {
; CHECK-LABEL: @add_nsw(
entry:
%cmp = icmp sgt i32 %s, 0
br i1 %cmp, label %positive, label %out
positive:
%add = add nsw i32 %s, 1
%res = icmp sgt i32 %add, 0
br label %next
next:
; CHECK: next:
; CHECK: ret i1 true
ret i1 %res
out:
ret i1 false
}
define i1 @add_nsw2(i32 %s) {
; CHECK-LABEL: @add_nsw2(
entry:
%cmp = icmp sge i32 %s, 0
br i1 %cmp, label %positive, label %out
positive:
%add = add nsw i32 %s, 1
%res = icmp ne i32 %add, 0
br label %next
next:
; CHECK: next:
; CHECK: ret i1 true
ret i1 %res
out:
ret i1 false
}
define i1 @add_nuw(i32 %s) {
; CHECK-LABEL: @add_nuw(
entry:
%cmp = icmp ult i32 %s, 400
br i1 %cmp, label %positive, label %out
positive:
%add = add nsw i32 %s, 1
%res = icmp ne i32 %add, -100
br label %next
next:
; CHECK: next:
; CHECK: ret i1 true
ret i1 %res
out:
ret i1 false
}