maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

Revert "[ScalarEvolution] Re-enable Predicate implication from operations" 

This reverts commit rL298690

Causes failures on clang.

llvm-svn: 298693
This commit is contained in:
Max Kazantsev 2017-03-24 07:04:31 +00:00
parent ffc30781f4
commit 7696a7edf9
4 changed files with 16 additions and 534 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
llvm/include/llvm/Analysis/ScalarEvolution.h
View File

@ -976,20 +976,6 @@ private:
const SCEV *RHS, const SCEV *FoundLHS,
const SCEV *FoundRHS);
/// Test whether the condition described by Pred, LHS, and RHS is true
/// whenever the condition described by Pred, FoundLHS, and FoundRHS is
/// true. Here LHS is an operation that includes FoundLHS as one of its
/// arguments.
bool isImpliedViaOperations(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
const SCEV *FoundLHS, const SCEV *FoundRHS,
unsigned Depth = 0);
/// Test whether the condition described by Pred, LHS, and RHS is true.
/// Use only simple non-recursive types of checks, such as range analysis etc.
bool isKnownViaSimpleReasoning(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS);
/// Test whether the condition described by Pred, LHS, and RHS is true
/// whenever the condition described by Pred, FoundLHS, and FoundRHS is
/// true.
@ -1137,9 +1123,6 @@ public:
/// return true. For pointer types, this is the pointer-sized integer type.
Type *getEffectiveSCEVType(Type *Ty) const;
// Returns a wider type among {Ty1, Ty2}.
Type *getWiderType(Type *Ty1, Type *Ty2) const;
/// Return true if the SCEV is a scAddRecExpr or it contains
/// scAddRecExpr. The result will be cached in HasRecMap.
///

175
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -137,11 +137,6 @@ static cl::opt<unsigned> MaxSCEVCompareDepth(
cl::desc("Maximum depth of recursive SCEV complexity comparisons"),
cl::init(32));
static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth(
"scalar-evolution-max-scev-operations-implication-depth", cl::Hidden,
cl::desc("Maximum depth of recursive SCEV operations implication analysis"),
cl::init(4));
static cl::opt<unsigned> MaxValueCompareDepth(
"scalar-evolution-max-value-compare-depth", cl::Hidden,
cl::desc("Maximum depth of recursive value complexity comparisons"),
@ -3423,10 +3418,6 @@ Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
return getDataLayout().getIntPtrType(Ty);
}
Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
}
const SCEV *ScalarEvolution::getCouldNotCompute() {
return CouldNotCompute.get();
}
@ -8568,149 +8559,19 @@ static bool IsKnownPredicateViaMinOrMax(ScalarEvolution &SE,
llvm_unreachable("covered switch fell through?!");
}
bool ScalarEvolution::isImpliedViaOperations(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
const SCEV *FoundLHS,
const SCEV *FoundRHS,
unsigned Depth) {
// We want to avoid hurting the compile time with analysis of too big trees.
if (Depth > MaxSCEVOperationsImplicationDepth)
return false;
// We only want to work with ICMP_SGT comparison so far.
// TODO: Extend to ICMP_UGT?
if (Pred == ICmpInst::ICMP_SLT) {
Pred = ICmpInst::ICMP_SGT;
std::swap(LHS, RHS);
std::swap(FoundLHS, FoundRHS);
}
if (Pred != ICmpInst::ICMP_SGT)
return false;
auto GetOpFromSExt = [&](const SCEV *S) {
if (auto *Ext = dyn_cast<SCEVSignExtendExpr>(S))
return Ext->getOperand();
// TODO: If S is a SCEVConstant then you can cheaply "strip" the sext off
// the constant in some cases.
return S;
};
// Acquire values from extensions.
auto *OrigFoundLHS = FoundLHS;
LHS = GetOpFromSExt(LHS);
FoundLHS = GetOpFromSExt(FoundLHS);
// Is the SGT predicate can be proved trivially or using the found context.
auto IsSGTViaContext = [&](const SCEV *S1, const SCEV *S2) {
assert(S1->getType() == S2->getType() && "Proving for wrong types?");
return isKnownViaSimpleReasoning(ICmpInst::ICMP_SGT, S1, S2) ||
isImpliedViaOperations(ICmpInst::ICMP_SGT, S1, S2, OrigFoundLHS,
FoundRHS, Depth + 1);
};
if (auto *LHSAddExpr = dyn_cast<SCEVAddExpr>(LHS)) {
// We want to avoid creation of any new non-constant SCEV. Since we are
// going to compare the operands to RHS, we should be certain that we don't
// need any type conversions for this. So let's decline all cases when the
// types of LHS and RHS do not match.
// TODO: Maybe try to get RHS from sext to catch more cases?
if (LHSAddExpr->getType() != RHS->getType())
return false;
// Should not overflow.
if (!LHSAddExpr->hasNoSignedWrap())
return false;
auto *LL = LHSAddExpr->getOperand(0);
auto *LR = LHSAddExpr->getOperand(1);
auto *MinusOne = getNegativeSCEV(getOne(RHS->getType()));
// Checks that S1 >= 0 && S2 > RHS, trivially or using the found context.
auto IsSumGreaterThanRHS = [&](const SCEV *S1, const SCEV *S2) {
return IsSGTViaContext(S1, MinusOne) && IsSGTViaContext(S2, RHS);
};
// Try to prove the following rule:
// (LHS = LL + LR) && (LL >= 0) && (LR > RHS) => (LHS > RHS).
// (LHS = LL + LR) && (LR >= 0) && (LL > RHS) => (LHS > RHS).
if (IsSumGreaterThanRHS(LL, LR) || IsSumGreaterThanRHS(LR, LL))
return true;
} else if (auto *LHSUnknownExpr = dyn_cast<SCEVUnknown>(LHS)) {
Value *LL, *LR;
// FIXME: Once we have SDiv implemented, we can get rid of this matching.
using namespace llvm::PatternMatch;
if (match(LHSUnknownExpr->getValue(), m_SDiv(m_Value(LL), m_Value(LR)))) {
// Rules for division.
// We are going to perform some comparisons with Denominator and its
// derivative expressions. In general case, creating a SCEV for it may
// lead to a complex analysis of the entire graph, and in particular it
// can request trip count recalculation for the same loop. This would
// cache as SCEVCouldNotCompute to avoid the infinite recursion. This is a
// sad thing. To avoid this, we only want to create SCEVs that are
// constants in this section. So we bail if Denominator is not a constant.
if (!isa<ConstantInt>(LR))
return false;
auto *Denominator = cast<SCEVConstant>(getSCEV(LR));
// We want to make sure that LHS = FoundLHS / Denominator. If it is so,
// then a SCEV for the numerator already exists and matches with FoundLHS.
auto *Numerator = getExistingSCEV(LL);
// Make sure that it exists and has the same type.
if (!Numerator || Numerator->getType() != FoundLHS->getType())
return false;
// Make sure that the numerator matches with FoundLHs and the denominator
// is positive.
if (!HasSameValue(Numerator, FoundLHS) || !isKnownPositive(Denominator))
return false;
// Given that:
// FoundLHS > FoundRHS, LHS = FoundLHS / Denominator, Denominator > 0.
auto *Ty2 = getWiderType(Denominator->getType(), FoundRHS->getType());
auto *DenominatorExt = getNoopOrSignExtend(Denominator, Ty2);
auto *FoundRHSExt = getNoopOrSignExtend(FoundRHS, Ty2);
// Try to prove the following rule:
// (FoundRHS > Denominator - 2) && (RHS <= 0) => (LHS > RHS).
// For example, given that FoundLHS > 2. It means that FoundLHS is at
// least 3. If we divide it by Denominator < 4, we will have at least 1.
auto *DenomMinusTwo = getMinusSCEV(DenominatorExt, getConstant(Ty2, 2));
if (isKnownNonPositive(RHS) &&
IsSGTViaContext(FoundRHSExt, DenomMinusTwo))
return true;
// Try to prove the following rule:
// (FoundRHS > -1 - Denominator) && (RHS < 0) => (LHS > RHS).
// For example, given that FoundLHS > -3. Then FoundLHS is at least -2.
// If we divide it by Denominator > 2, then:
// 1. If FoundLHS is negative, then the result is 0.
// 2. If FoundLHS is non-negative, then the result is non-negative.
// Anyways, the result is non-negative.
auto *MinusOne = getNegativeSCEV(getOne(Ty2));
auto *NegDenomMinusOne = getMinusSCEV(MinusOne, DenominatorExt);
if (isKnownNegative(RHS) &&
IsSGTViaContext(FoundRHSExt, NegDenomMinusOne))
return true;
}
}
return false;
}
bool
ScalarEvolution::isKnownViaSimpleReasoning(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS) {
return isKnownPredicateViaConstantRanges(Pred, LHS, RHS) ||
IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) ||
IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) ||
isKnownPredicateViaNoOverflow(Pred, LHS, RHS);
}
bool
ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
const SCEV *LHS, const SCEV *RHS,
const SCEV *FoundLHS,
const SCEV *FoundRHS) {
auto IsKnownPredicateFull =
[this](ICmpInst::Predicate Pred, const SCEV *LHS, const SCEV *RHS) {
return isKnownPredicateViaConstantRanges(Pred, LHS, RHS) ||
IsKnownPredicateViaMinOrMax(*this, Pred, LHS, RHS) ||
IsKnownPredicateViaAddRecStart(*this, Pred, LHS, RHS) ||
isKnownPredicateViaNoOverflow(Pred, LHS, RHS);
};
switch (Pred) {
default: llvm_unreachable("Unexpected ICmpInst::Predicate value!");
case ICmpInst::ICMP_EQ:
@ -8720,34 +8581,30 @@ ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
break;
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
if (isKnownViaSimpleReasoning(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
isKnownViaSimpleReasoning(ICmpInst::ICMP_SGE, RHS, FoundRHS))
if (IsKnownPredicateFull(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
IsKnownPredicateFull(ICmpInst::ICMP_SGE, RHS, FoundRHS))
return true;
break;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
if (isKnownViaSimpleReasoning(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
isKnownViaSimpleReasoning(ICmpInst::ICMP_SLE, RHS, FoundRHS))
if (IsKnownPredicateFull(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
IsKnownPredicateFull(ICmpInst::ICMP_SLE, RHS, FoundRHS))
return true;
break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
if (isKnownViaSimpleReasoning(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
isKnownViaSimpleReasoning(ICmpInst::ICMP_UGE, RHS, FoundRHS))
if (IsKnownPredicateFull(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
IsKnownPredicateFull(ICmpInst::ICMP_UGE, RHS, FoundRHS))
return true;
break;
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
if (isKnownViaSimpleReasoning(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
isKnownViaSimpleReasoning(ICmpInst::ICMP_ULE, RHS, FoundRHS))
if (IsKnownPredicateFull(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
IsKnownPredicateFull(ICmpInst::ICMP_ULE, RHS, FoundRHS))
return true;
break;
}
// Maybe it can be proved via operations?
if (isImpliedViaOperations(Pred, LHS, RHS, FoundLHS, FoundRHS))
return true;
return false;
}

27
llvm/test/Analysis/ScalarEvolution/implied-via-addition.ll
View File

@ -1,27 +0,0 @@
; RUN: opt -indvars -S < %s | FileCheck %s
declare void @use(i1)
declare void @llvm.experimental.guard(i1, ...)
define void @test_01(i8 %t) {
; CHECK-LABEL: test_01
entry:
%st = sext i8 %t to i16
%cmp1 = icmp slt i16 %st, 42
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %loop
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
}

331
llvm/test/Analysis/ScalarEvolution/implied-via-division.ll
View File

@ -1,331 +0,0 @@
; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
declare void @llvm.experimental.guard(i1, ...)
define void @test_1(i32 %n) nounwind {
; Prove that (n > 1) ===> (n / 2 > 0).
; CHECK: Determining loop execution counts for: @test_1
; CHECK: Loop %header: backedge-taken count is (-1 + %n.div.2)<nsw>
entry:
%cmp1 = icmp sgt i32 %n, 1
%n.div.2 = sdiv i32 %n, 2
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%exitcond = icmp sgt i32 %n.div.2, %indvar.next
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_1neg(i32 %n) nounwind {
; Prove that (n > 0) =\=> (n / 2 > 0).
; CHECK: Determining loop execution counts for: @test_1neg
; CHECK: Loop %header: backedge-taken count is (-1 + (1 smax %n.div.2))<nsw>
entry:
%cmp1 = icmp sgt i32 %n, 0
%n.div.2 = sdiv i32 %n, 2
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%exitcond = icmp sgt i32 %n.div.2, %indvar.next
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_2(i32 %n) nounwind {
; Prove that (n >= 2) ===> (n / 2 > 0).
; CHECK: Determining loop execution counts for: @test_2
; CHECK: Loop %header: backedge-taken count is (-1 + %n.div.2)<nsw>
entry:
%cmp1 = icmp sge i32 %n, 2
%n.div.2 = sdiv i32 %n, 2
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%exitcond = icmp sgt i32 %n.div.2, %indvar.next
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_2neg(i32 %n) nounwind {
; Prove that (n >= 1) =\=> (n / 2 > 0).
; CHECK: Determining loop execution counts for: @test_2neg
; CHECK: Loop %header: backedge-taken count is (-1 + (1 smax %n.div.2))<nsw>
entry:
%cmp1 = icmp sge i32 %n, 1
%n.div.2 = sdiv i32 %n, 2
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%exitcond = icmp sgt i32 %n.div.2, %indvar.next
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_3(i32 %n) nounwind {
; Prove that (n > -2) ===> (n / 2 >= 0).
; CHECK: Determining loop execution counts for: @test_3
; CHECK: Loop %header: backedge-taken count is (1 + %n.div.2)<nsw>
entry:
%cmp1 = icmp sgt i32 %n, -2
%n.div.2 = sdiv i32 %n, 2
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%exitcond = icmp sge i32 %n.div.2, %indvar
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_3neg(i32 %n) nounwind {
; Prove that (n > -3) =\=> (n / 2 >= 0).
; CHECK: Determining loop execution counts for: @test_3neg
; CHECK: Loop %header: backedge-taken count is (0 smax (1 + %n.div.2)<nsw>)
entry:
%cmp1 = icmp sgt i32 %n, -3
%n.div.2 = sdiv i32 %n, 2
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%exitcond = icmp sge i32 %n.div.2, %indvar
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_4(i32 %n) nounwind {
; Prove that (n >= -1) ===> (n / 2 >= 0).
; CHECK: Determining loop execution counts for: @test_4
; CHECK: Loop %header: backedge-taken count is (1 + %n.div.2)<nsw>
entry:
%cmp1 = icmp sge i32 %n, -1
%n.div.2 = sdiv i32 %n, 2
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%exitcond = icmp sge i32 %n.div.2, %indvar
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_4neg(i32 %n) nounwind {
; Prove that (n >= -2) =\=> (n / 2 >= 0).
; CHECK: Determining loop execution counts for: @test_4neg
; CHECK: Loop %header: backedge-taken count is (0 smax (1 + %n.div.2)<nsw>)
entry:
%cmp1 = icmp sge i32 %n, -2
%n.div.2 = sdiv i32 %n, 2
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i32 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i32 %indvar, 1
%exitcond = icmp sge i32 %n.div.2, %indvar
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_ext_01(i32 %n) nounwind {
; Prove that (n > 1) ===> (n / 2 > 0).
; CHECK: Determining loop execution counts for: @test_ext_01
; CHECK: Loop %header: backedge-taken count is (-1 + (sext i32 %n.div.2 to i64))<nsw>
entry:
%cmp1 = icmp sgt i32 %n, 1
%n.div.2 = sdiv i32 %n, 2
%n.div.2.ext = sext i32 %n.div.2 to i64
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i64 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i64 %indvar, 1
%exitcond = icmp sgt i64 %n.div.2.ext, %indvar.next
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_ext_01neg(i32 %n) nounwind {
; Prove that (n > 0) =\=> (n / 2 > 0).
; CHECK: Determining loop execution counts for: @test_ext_01neg
; CHECK: Loop %header: backedge-taken count is (-1 + (1 smax (sext i32 %n.div.2 to i64)))<nsw>
entry:
%cmp1 = icmp sgt i32 %n, 0
%n.div.2 = sdiv i32 %n, 2
%n.div.2.ext = sext i32 %n.div.2 to i64
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i64 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i64 %indvar, 1
%exitcond = icmp sgt i64 %n.div.2.ext, %indvar.next
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_ext_02(i32 %n) nounwind {
; Prove that (n >= 2) ===> (n / 2 > 0).
; CHECK: Determining loop execution counts for: @test_ext_02
; CHECK: Loop %header: backedge-taken count is (-1 + (sext i32 %n.div.2 to i64))<nsw>
entry:
%cmp1 = icmp sge i32 %n, 2
%n.div.2 = sdiv i32 %n, 2
%n.div.2.ext = sext i32 %n.div.2 to i64
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i64 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i64 %indvar, 1
%exitcond = icmp sgt i64 %n.div.2.ext, %indvar.next
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_ext_02neg(i32 %n) nounwind {
; Prove that (n >= 1) =\=> (n / 2 > 0).
; CHECK: Determining loop execution counts for: @test_ext_02neg
; CHECK: Loop %header: backedge-taken count is (-1 + (1 smax (sext i32 %n.div.2 to i64)))<nsw>
entry:
%cmp1 = icmp sge i32 %n, 1
%n.div.2 = sdiv i32 %n, 2
%n.div.2.ext = sext i32 %n.div.2 to i64
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i64 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i64 %indvar, 1
%exitcond = icmp sgt i64 %n.div.2.ext, %indvar.next
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_ext_03(i32 %n) nounwind {
; Prove that (n > -2) ===> (n / 2 >= 0).
; CHECK: Determining loop execution counts for: @test_ext_03
; CHECK: Loop %header: backedge-taken count is (1 + (sext i32 %n.div.2 to i64))<nsw>
entry:
%cmp1 = icmp sgt i32 %n, -2
%n.div.2 = sdiv i32 %n, 2
%n.div.2.ext = sext i32 %n.div.2 to i64
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i64 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i64 %indvar, 1
%exitcond = icmp sge i64 %n.div.2.ext, %indvar
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_ext_03neg(i32 %n) nounwind {
; Prove that (n > -3) =\=> (n / 2 >= 0).
; CHECK: Determining loop execution counts for: @test_ext_03neg
; CHECK: Loop %header: backedge-taken count is (0 smax (1 + (sext i32 %n.div.2 to i64))<nsw>)
entry:
%cmp1 = icmp sgt i32 %n, -3
%n.div.2 = sdiv i32 %n, 2
%n.div.2.ext = sext i32 %n.div.2 to i64
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i64 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i64 %indvar, 1
%exitcond = icmp sge i64 %n.div.2.ext, %indvar
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_ext_04(i32 %n) nounwind {
; Prove that (n >= -1) ===> (n / 2 >= 0).
; CHECK: Determining loop execution counts for: @test_ext_04
; CHECK: Loop %header: backedge-taken count is (1 + (sext i32 %n.div.2 to i64))<nsw>
entry:
%cmp1 = icmp sge i32 %n, -1
%n.div.2 = sdiv i32 %n, 2
%n.div.2.ext = sext i32 %n.div.2 to i64
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i64 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i64 %indvar, 1
%exitcond = icmp sge i64 %n.div.2.ext, %indvar
br i1 %exitcond, label %header, label %exit
exit:
ret void
}
define void @test_ext_04neg(i32 %n) nounwind {
; Prove that (n >= -2) =\=> (n / 2 >= 0).
; CHECK: Determining loop execution counts for: @test_ext_04neg
; CHECK: Loop %header: backedge-taken count is (0 smax (1 + (sext i32 %n.div.2 to i64))<nsw>)
entry:
%cmp1 = icmp sge i32 %n, -2
%n.div.2 = sdiv i32 %n, 2
%n.div.2.ext = sext i32 %n.div.2 to i64
call void(i1, ...) @llvm.experimental.guard(i1 %cmp1) [ "deopt"() ]
br label %header
header:
%indvar = phi i64 [ %indvar.next, %header ], [ 0, %entry ]
%indvar.next = add i64 %indvar, 1
%exitcond = icmp sge i64 %n.div.2.ext, %indvar
br i1 %exitcond, label %header, label %exit
exit:
ret void
}