[llvm] 02e08d0 - Revert "[SCEV] Preserve divisibility and min/max information in applyLoopGuards"
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Thu Feb 23 04:44:27 PST 2023
Author: komalon1
Date: 2023-02-23T14:44:03+02:00
New Revision: 02e08d06aac947fb15f2d5750e0d29f5b68186f5
URL: https://github.com/llvm/llvm-project/commit/02e08d06aac947fb15f2d5750e0d29f5b68186f5
DIFF: https://github.com/llvm/llvm-project/commit/02e08d06aac947fb15f2d5750e0d29f5b68186f5.diff
LOG: Revert "[SCEV] Preserve divisibility and min/max information in applyLoopGuards"
This reverts commit 219ba2fb7b0ae89101f3c81a47fe4fc4aa80dea4.
Added:
Modified:
llvm/lib/Analysis/ScalarEvolution.cpp
llvm/test/Analysis/ScalarEvolution/trip-multiple-guard-info.ll
llvm/unittests/Analysis/ScalarEvolutionTest.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 4a5680d6a23df..5c2c12c7d0591 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -15034,91 +15034,6 @@ const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {
if (MatchRangeCheckIdiom())
return;
- // Return true if \p Expr is a MinMax SCEV expression with a constant
- // operand. If so, return in \p SCTy the SCEV type and in \p RHS the
- // non-constant operand and in \p LHS the constant operand.
- auto IsMinMaxSCEVWithConstant = [&](const SCEV *Expr, SCEVTypes &SCTy,
- const SCEV *&LHS, const SCEV *&RHS) {
- if (auto *MinMax = dyn_cast<SCEVMinMaxExpr>(Expr)) {
- if (MinMax->getNumOperands() != 2)
- return false;
- SCTy = MinMax->getSCEVType();
- if (!isa<SCEVConstant>(MinMax->getOperand(0)))
- return false;
- LHS = MinMax->getOperand(0);
- RHS = MinMax->getOperand(1);
- return true;
- }
- return false;
- };
-
- // Checks whether Expr is a non-negative constant, and Divisor is a positive
- // constant, and returns their APInt in ExprVal and in DivisorVal.
- auto GetNonNegExprAndPosDivisor = [&](const SCEV *Expr, const SCEV *Divisor,
- APInt &ExprVal, APInt &DivisorVal) {
- if (!isKnownNonNegative(Expr) || !isKnownPositive(Divisor))
- return false;
- auto *ConstExpr = dyn_cast<SCEVConstant>(Expr);
- auto *ConstDivisor = dyn_cast<SCEVConstant>(Divisor);
- if (!ConstExpr || !ConstDivisor)
- return false;
- ExprVal = ConstExpr->getAPInt();
- DivisorVal = ConstDivisor->getAPInt();
- return true;
- };
-
- // Return a new SCEV that modifies \p Expr to the closest number divides by
- // \p Divisor and greater or equal than Expr.
- // For now, only handle constant Expr and Divisor.
- auto GetNextSCEVDividesByDivisor = [&](const SCEV *Expr,
- const SCEV *Divisor) {
- APInt ExprVal;
- APInt DivisorVal;
- if (!GetNonNegExprAndPosDivisor(Expr, Divisor, ExprVal, DivisorVal))
- return Expr;
- APInt Rem = ExprVal.urem(DivisorVal);
- if (!Rem.isZero())
- // return the SCEV: Expr + Divisor - Expr % Divisor
- return getConstant(ExprVal + DivisorVal - Rem);
- return Expr;
- };
-
- // Return a new SCEV that modifies \p Expr to the closest number divides by
- // \p Divisor and less or equal than Expr.
- // For now, only handle constant Expr and Divisor.
- auto GetPreviousSCEVDividesByDivisor = [&](const SCEV *Expr,
- const SCEV *Divisor) {
- APInt ExprVal;
- APInt DivisorVal;
- if (!GetNonNegExprAndPosDivisor(Expr, Divisor, ExprVal, DivisorVal))
- return Expr;
- APInt Rem = ExprVal.urem(DivisorVal);
- // return the SCEV: Expr - Expr % Divisor
- return getConstant(ExprVal - Rem);
- };
-
- // Apply divisibilty by \p Divisor on MinMaxExpr with constant values,
- // recursively. This is done by aligning up/down the constant value to the
- // Divisor.
- std::function<const SCEV *(const SCEV *, const SCEV *)>
- ApplyDivisibiltyOnMinMaxExpr = [&](const SCEV *MinMaxExpr,
- const SCEV *Divisor) {
- const SCEV *MinMaxLHS = nullptr, *MinMaxRHS = nullptr;
- SCEVTypes SCTy;
- if (!IsMinMaxSCEVWithConstant(MinMaxExpr, SCTy, MinMaxLHS, MinMaxRHS))
- return MinMaxExpr;
- auto IsMin =
- isa<SCEVSMinExpr>(MinMaxExpr) || isa<SCEVUMinExpr>(MinMaxExpr);
- assert(isKnownNonNegative(MinMaxLHS) &&
- "Expected non-negative operand!");
- auto *DivisibleExpr =
- IsMin ? GetPreviousSCEVDividesByDivisor(MinMaxLHS, Divisor)
- : GetNextSCEVDividesByDivisor(MinMaxLHS, Divisor);
- SmallVector<const SCEV *> Ops = {
- ApplyDivisibiltyOnMinMaxExpr(MinMaxRHS, Divisor), DivisibleExpr};
- return getMinMaxExpr(SCTy, Ops);
- };
-
// If we have LHS == 0, check if LHS is computing a property of some unknown
// SCEV %v which we can rewrite %v to express explicitly.
const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS);
@@ -15130,12 +15045,7 @@ const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {
const SCEV *URemRHS = nullptr;
if (matchURem(LHS, URemLHS, URemRHS)) {
if (const SCEVUnknown *LHSUnknown = dyn_cast<SCEVUnknown>(URemLHS)) {
- auto I = RewriteMap.find(LHSUnknown);
- const SCEV *RewrittenLHS =
- I != RewriteMap.end() ? I->second : LHSUnknown;
- RewrittenLHS = ApplyDivisibiltyOnMinMaxExpr(RewrittenLHS, URemRHS);
- const auto *Multiple =
- getMulExpr(getUDivExpr(RewrittenLHS, URemRHS), URemRHS);
+ const auto *Multiple = getMulExpr(getUDivExpr(URemLHS, URemRHS), URemRHS);
RewriteMap[LHSUnknown] = Multiple;
ExprsToRewrite.push_back(LHSUnknown);
return;
@@ -15158,128 +15068,48 @@ const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {
auto I = RewriteMap.find(LHS);
const SCEV *RewrittenLHS = I != RewriteMap.end() ? I->second : LHS;
- // Check for the SCEV expression (A /u B) * B while B is a constant, inside
- // \p Expr. The check is done recuresively on \p Expr, which is assumed to
- // be a composition of Min/Max SCEVs. Return whether the SCEV expression (A
- // /u B) * B was found, and return the divisor B in \p DividesBy. For
- // example, if Expr = umin (umax ((A /u 8) * 8, 16), 64), return true since
- // (A /u 8) * 8 matched the pattern, and return the constant SCEV 8 in \p
- // DividesBy.
- std::function<bool(const SCEV *, const SCEV *&)> HasDivisibiltyInfo =
- [&](const SCEV *Expr, const SCEV *&DividesBy) {
- if (auto *Mul = dyn_cast<SCEVMulExpr>(Expr)) {
- if (Mul->getNumOperands() != 2)
- return false;
- auto *MulLHS = Mul->getOperand(0);
- auto *MulRHS = Mul->getOperand(1);
- if (isa<SCEVConstant>(MulLHS))
- std::swap(MulLHS, MulRHS);
- if (auto *Div = dyn_cast<SCEVUDivExpr>(MulLHS)) {
- if (Div->getOperand(1) == MulRHS) {
- DividesBy = MulRHS;
- return true;
- }
- }
- }
- if (auto *MinMax = dyn_cast<SCEVMinMaxExpr>(Expr)) {
- return HasDivisibiltyInfo(MinMax->getOperand(0), DividesBy) ||
- HasDivisibiltyInfo(MinMax->getOperand(1), DividesBy);
- }
- return false;
- };
-
- // Return true if Expr known to divide by \p DividesBy.
- std::function<bool(const SCEV *, const SCEV *&)> IsKnownToDivideBy =
- [&](const SCEV *Expr, const SCEV *DividesBy) {
- if (getURemExpr(Expr, DividesBy)->isZero())
- return true;
- if (auto *MinMax = dyn_cast<SCEVMinMaxExpr>(Expr)) {
- return IsKnownToDivideBy(MinMax->getOperand(0), DividesBy) &&
- IsKnownToDivideBy(MinMax->getOperand(1), DividesBy);
- }
- return false;
- };
-
- const SCEV *DividesBy = nullptr;
- if (HasDivisibiltyInfo(RewrittenLHS, DividesBy))
- // Check that the whole expression is divided by DividesBy
- DividesBy =
- IsKnownToDivideBy(RewrittenLHS, DividesBy) ? DividesBy : nullptr;
-
const SCEV *RewrittenRHS = nullptr;
switch (Predicate) {
case CmpInst::ICMP_ULT: {
if (RHS->getType()->isPointerTy())
break;
const SCEV *One = getOne(RHS->getType());
- auto *ModifiedRHS = getMinusSCEV(getUMaxExpr(RHS, One), One);
- ModifiedRHS =
- DividesBy ? GetPreviousSCEVDividesByDivisor(ModifiedRHS, DividesBy)
- : ModifiedRHS;
- RewrittenRHS = getUMinExpr(RewrittenLHS, ModifiedRHS);
+ RewrittenRHS =
+ getUMinExpr(RewrittenLHS, getMinusSCEV(getUMaxExpr(RHS, One), One));
break;
}
- case CmpInst::ICMP_SLT: {
- auto *ModifiedRHS = getMinusSCEV(RHS, getOne(RHS->getType()));
- ModifiedRHS =
- DividesBy ? GetPreviousSCEVDividesByDivisor(ModifiedRHS, DividesBy)
- : ModifiedRHS;
- RewrittenRHS = getSMinExpr(RewrittenLHS, ModifiedRHS);
+ case CmpInst::ICMP_SLT:
+ RewrittenRHS =
+ getSMinExpr(RewrittenLHS, getMinusSCEV(RHS, getOne(RHS->getType())));
break;
- }
- case CmpInst::ICMP_ULE: {
- auto *ModifiedRHS =
- DividesBy ? GetPreviousSCEVDividesByDivisor(RHS, DividesBy) : RHS;
- RewrittenRHS = getUMinExpr(RewrittenLHS, ModifiedRHS);
+ case CmpInst::ICMP_ULE:
+ RewrittenRHS = getUMinExpr(RewrittenLHS, RHS);
break;
- }
- case CmpInst::ICMP_SLE: {
- auto *ModifiedRHS =
- DividesBy ? GetPreviousSCEVDividesByDivisor(RHS, DividesBy) : RHS;
- RewrittenRHS = getSMinExpr(RewrittenLHS, ModifiedRHS);
+ case CmpInst::ICMP_SLE:
+ RewrittenRHS = getSMinExpr(RewrittenLHS, RHS);
break;
- }
- case CmpInst::ICMP_UGT: {
- auto *ModifiedRHS = getAddExpr(RHS, getOne(RHS->getType()));
- ModifiedRHS = DividesBy
- ? GetNextSCEVDividesByDivisor(ModifiedRHS, DividesBy)
- : ModifiedRHS;
- RewrittenRHS = getUMaxExpr(RewrittenLHS, ModifiedRHS);
+ case CmpInst::ICMP_UGT:
+ RewrittenRHS =
+ getUMaxExpr(RewrittenLHS, getAddExpr(RHS, getOne(RHS->getType())));
break;
- }
- case CmpInst::ICMP_SGT: {
- auto *ModifiedRHS = getAddExpr(RHS, getOne(RHS->getType()));
- ModifiedRHS = DividesBy
- ? GetNextSCEVDividesByDivisor(ModifiedRHS, DividesBy)
- : ModifiedRHS;
- RewrittenRHS = getSMaxExpr(RewrittenLHS, ModifiedRHS);
+ case CmpInst::ICMP_SGT:
+ RewrittenRHS =
+ getSMaxExpr(RewrittenLHS, getAddExpr(RHS, getOne(RHS->getType())));
break;
- }
- case CmpInst::ICMP_UGE: {
- auto *ModifiedRHS =
- DividesBy ? GetNextSCEVDividesByDivisor(RHS, DividesBy) : RHS;
- RewrittenRHS = getUMaxExpr(RewrittenLHS, ModifiedRHS);
+ case CmpInst::ICMP_UGE:
+ RewrittenRHS = getUMaxExpr(RewrittenLHS, RHS);
break;
- }
- case CmpInst::ICMP_SGE: {
- auto *ModifiedRHS =
- DividesBy ? GetNextSCEVDividesByDivisor(RHS, DividesBy) : RHS;
- RewrittenRHS = getSMaxExpr(RewrittenLHS, ModifiedRHS);
+ case CmpInst::ICMP_SGE:
+ RewrittenRHS = getSMaxExpr(RewrittenLHS, RHS);
break;
- }
case CmpInst::ICMP_EQ:
if (isa<SCEVConstant>(RHS))
RewrittenRHS = RHS;
break;
case CmpInst::ICMP_NE:
if (isa<SCEVConstant>(RHS) &&
- cast<SCEVConstant>(RHS)->getValue()->isNullValue()) {
- auto *ModifiedRHS = getOne(RHS->getType());
- ModifiedRHS = DividesBy
- ? GetNextSCEVDividesByDivisor(ModifiedRHS, DividesBy)
- : ModifiedRHS;
- RewrittenRHS = getUMaxExpr(RewrittenLHS, ModifiedRHS);
- }
+ cast<SCEVConstant>(RHS)->getValue()->isNullValue())
+ RewrittenRHS = getUMaxExpr(RewrittenLHS, getOne(RHS->getType()));
break;
default:
break;
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-multiple-guard-info.ll b/llvm/test/Analysis/ScalarEvolution/trip-multiple-guard-info.ll
index 492ed9c4d2653..cfa91e3cc7473 100644
--- a/llvm/test/Analysis/ScalarEvolution/trip-multiple-guard-info.ll
+++ b/llvm/test/Analysis/ScalarEvolution/trip-multiple-guard-info.ll
@@ -125,7 +125,7 @@ define void @test_trip_multiple_4_ugt_5_order_swapped(i32 %num) {
; CHECK-NEXT: Loop %for.body: symbolic max backedge-taken count is (-1 + %num)
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (-1 + %num)
; CHECK-NEXT: Predicates:
-; CHECK: Loop %for.body: Trip multiple is 4
+; CHECK: Loop %for.body: Trip multiple is 2
;
entry:
%u = urem i32 %num, 4
@@ -196,7 +196,7 @@ define void @test_trip_multiple_4_sgt_5_order_swapped(i32 %num) {
; CHECK-NEXT: Loop %for.body: symbolic max backedge-taken count is (-1 + %num)
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (-1 + %num)
; CHECK-NEXT: Predicates:
-; CHECK: Loop %for.body: Trip multiple is 4
+; CHECK: Loop %for.body: Trip multiple is 2
;
entry:
%u = urem i32 %num, 4
@@ -267,7 +267,7 @@ define void @test_trip_multiple_4_uge_5_order_swapped(i32 %num) {
; CHECK-NEXT: Loop %for.body: symbolic max backedge-taken count is (-1 + %num)
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (-1 + %num)
; CHECK-NEXT: Predicates:
-; CHECK: Loop %for.body: Trip multiple is 4
+; CHECK: Loop %for.body: Trip multiple is 1
;
entry:
%u = urem i32 %num, 4
@@ -338,7 +338,7 @@ define void @test_trip_multiple_4_sge_5_order_swapped(i32 %num) {
; CHECK-NEXT: Loop %for.body: symbolic max backedge-taken count is (-1 + %num)
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (-1 + %num)
; CHECK-NEXT: Predicates:
-; CHECK: Loop %for.body: Trip multiple is 4
+; CHECK: Loop %for.body: Trip multiple is 1
;
entry:
%u = urem i32 %num, 4
@@ -409,7 +409,7 @@ define void @test_trip_multiple_4_upper_lower_bounds(i32 %num) {
; CHECK-NEXT: Loop %for.body: symbolic max backedge-taken count is (-1 + %num)
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (-1 + %num)
; CHECK-NEXT: Predicates:
-; CHECK: Loop %for.body: Trip multiple is 4
+; CHECK: Loop %for.body: Trip multiple is 1
;
entry:
%cmp.1 = icmp uge i32 %num, 5
@@ -446,7 +446,7 @@ define void @test_trip_multiple_4_upper_lower_bounds_swapped1(i32 %num) {
; CHECK-NEXT: Loop %for.body: symbolic max backedge-taken count is (-1 + %num)
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (-1 + %num)
; CHECK-NEXT: Predicates:
-; CHECK: Loop %for.body: Trip multiple is 4
+; CHECK: Loop %for.body: Trip multiple is 1
;
entry:
%cmp.1 = icmp uge i32 %num, 5
@@ -483,7 +483,7 @@ define void @test_trip_multiple_4_upper_lower_bounds_swapped2(i32 %num) {
; CHECK-NEXT: Loop %for.body: symbolic max backedge-taken count is (-1 + %num)
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (-1 + %num)
; CHECK-NEXT: Predicates:
-; CHECK: Loop %for.body: Trip multiple is 4
+; CHECK: Loop %for.body: Trip multiple is 1
;
entry:
%cmp.1 = icmp uge i32 %num, 5
diff --git a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
index d0fec1ab2c570..8756e2c66c25a 100644
--- a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
+++ b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
@@ -1744,42 +1744,4 @@ TEST_F(ScalarEvolutionsTest, ComputeMaxTripCountFromMultiDemArray) {
});
}
-TEST_F(ScalarEvolutionsTest, ApplyLoopGuards) {
- LLVMContext C;
- SMDiagnostic Err;
- std::unique_ptr<Module> M = parseAssemblyString(
- "declare void @llvm.assume(i1)\n"
- "define void @test(i32 %num) {\n"
- "entry:\n"
- " %u = urem i32 %num, 4\n"
- " %cmp = icmp eq i32 %u, 0\n"
- " tail call void @llvm.assume(i1 %cmp)\n"
- " %cmp.1 = icmp ugt i32 %num, 0\n"
- " tail call void @llvm.assume(i1 %cmp.1)\n"
- " br label %for.body\n"
- "for.body:\n"
- " %i.010 = phi i32 [ 0, %entry ], [ %inc, %for.body ]\n"
- " %inc = add nuw nsw i32 %i.010, 1\n"
- " %cmp2 = icmp ult i32 %inc, %num\n"
- " br i1 %cmp2, label %for.body, label %exit\n"
- "exit:\n"
- " ret void\n"
- "}\n",
- Err, C);
-
- ASSERT_TRUE(M && "Could not parse module?");
- ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
-
- runWithSE(*M, "test", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
- auto *TCScev = SE.getSCEV(getArgByName(F, "num"));
- auto *ApplyLoopGuardsTC = SE.applyLoopGuards(TCScev, *LI.begin());
- // Assert that the new TC is (4 * ((4 umax %num) /u 4))
- APInt Four(32, 4);
- auto *Constant4 = SE.getConstant(Four);
- auto *Max = SE.getUMaxExpr(TCScev, Constant4);
- auto *Mul = SE.getMulExpr(SE.getUDivExpr(Max, Constant4), Constant4);
- ASSERT_TRUE(Mul == ApplyLoopGuardsTC);
- });
-}
-
} // end namespace llvm
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