}
/// InsertBinop - Insert the specified binary operator, doing a small amount
-/// of work to avoid inserting an obviously redundant operation.
+/// of work to avoid inserting an obviously redundant operation, and hoisting
+/// to an outer loop when the opportunity is there and it is safe.
Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
- Value *LHS, Value *RHS) {
+ Value *LHS, Value *RHS, bool IsSafeToHoist) {
// Fold a binop with constant operands.
if (Constant *CLHS = dyn_cast<Constant>(LHS))
if (Constant *CRHS = dyn_cast<Constant>(RHS))
DebugLoc Loc = Builder.GetInsertPoint()->getDebugLoc();
SCEVInsertPointGuard Guard(Builder, this);
- // Move the insertion point out of as many loops as we can.
- while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
- if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS)) break;
- BasicBlock *Preheader = L->getLoopPreheader();
- if (!Preheader) break;
+ if (IsSafeToHoist) {
+ // Move the insertion point out of as many loops as we can.
+ while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
+ if (!L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS)) break;
+ BasicBlock *Preheader = L->getLoopPreheader();
+ if (!Preheader) break;
- // Ok, move up a level.
- Builder.SetInsertPoint(Preheader->getTerminator());
+ // Ok, move up a level.
+ Builder.SetInsertPoint(Preheader->getTerminator());
+ }
}
// If we haven't found this binop, insert it.
// Instead of doing a negate and add, just do a subtract.
Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty);
Sum = InsertNoopCastOfTo(Sum, Ty);
- Sum = InsertBinop(Instruction::Sub, Sum, W);
+ Sum = InsertBinop(Instruction::Sub, Sum, W, /*IsSafeToHoist*/ true);
++I;
} else {
// A simple add.
Sum = InsertNoopCastOfTo(Sum, Ty);
// Canonicalize a constant to the RHS.
if (isa<Constant>(Sum)) std::swap(Sum, W);
- Sum = InsertBinop(Instruction::Add, Sum, W);
+ Sum = InsertBinop(Instruction::Add, Sum, W, /*IsSafeToHoist*/ true);
++I;
}
}
if (Exponent & 1)
Result = P;
for (uint64_t BinExp = 2; BinExp <= Exponent; BinExp <<= 1) {
- P = InsertBinop(Instruction::Mul, P, P);
+ P = InsertBinop(Instruction::Mul, P, P, /*IsSafeToHoist*/ true);
if (Exponent & BinExp)
- Result = Result ? InsertBinop(Instruction::Mul, Result, P) : P;
+ Result = Result ? InsertBinop(Instruction::Mul, Result, P,
+ /*IsSafeToHoist*/ true)
+ : P;
}
I = E;
} else if (I->second->isAllOnesValue()) {
// Instead of doing a multiply by negative one, just do a negate.
Prod = InsertNoopCastOfTo(Prod, Ty);
- Prod = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), Prod);
+ Prod = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), Prod,
+ /*IsSafeToHoist*/ true);
++I;
} else {
// A simple mul.
// Canonicalize Prod*(1<<C) to Prod<<C.
assert(!Ty->isVectorTy() && "vector types are not SCEVable");
Prod = InsertBinop(Instruction::Shl, Prod,
- ConstantInt::get(Ty, RHS->logBase2()));
+ ConstantInt::get(Ty, RHS->logBase2()),
+ /*IsSafeToHoist*/ true);
} else {
- Prod = InsertBinop(Instruction::Mul, Prod, W);
+ Prod = InsertBinop(Instruction::Mul, Prod, W, /*IsSafeToHoist*/ true);
}
}
}
const APInt &RHS = SC->getAPInt();
if (RHS.isPowerOf2())
return InsertBinop(Instruction::LShr, LHS,
- ConstantInt::get(Ty, RHS.logBase2()));
+ ConstantInt::get(Ty, RHS.logBase2()),
+ /*IsSafeToHoist*/ true);
}
Value *RHS = expandCodeFor(S->getRHS(), Ty);
- return InsertBinop(Instruction::UDiv, LHS, RHS);
+ return InsertBinop(Instruction::UDiv, LHS, RHS,
+ /*IsSafeToHoist*/ SE.isKnownNonZero(S->getRHS()));
}
/// Move parts of Base into Rest to leave Base with the minimal
--- /dev/null
+; RUN: opt -loop-vectorize -force-vector-width=2 -S < %s 2>&1 | FileCheck %s
+; RUN: opt -indvars -S < %s 2>&1 | FileCheck %s -check-prefix=INDVARCHECK
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Produced from test-case:
+;
+; void testCountIncrLoop(unsigned char *ptr, int lim, int count, int val)
+; {
+; int inx = 0;
+; for (int outer_i = 0; outer_i < lim; ++outer_i) {
+; if (count > 0) { // At runtime, 'count' is 0, so the following code is dead.
+; int result = val;
+; int tmp = count;
+;
+; while (tmp < 8) {
+; result += val >> tmp;
+; tmp += count;
+; }
+;
+; ptr[inx++] = (unsigned char) result;
+; }
+; }
+; }
+;
+; No explicit division appears in the input, but a division is generated during
+; vectorization, and that division is a division-by-0 when the input 'count'
+; is 0, so it cannot be hoisted above the guard of 'count > 0'.
+
+; Verify that a 'udiv' does not appear in the 'loop1.preheader' block, and that
+; a 'udiv' has been inserted at the top of the 'while.body.preheader' block.
+define void @testCountIncrLoop(i8* %ptr, i32 %lim, i32 %count, i32 %val) {
+; CHECK-LABEL: @testCountIncrLoop(
+; CHECK-NEXT: entry:
+; CHECK: loop1.preheader:
+; CHECK-NOT: udiv
+; CHECK: loop1.body:
+; CHECK: while.cond.preheader:
+; CHECK: while.body.preheader:
+; CHECK-NEXT: [[TMP1:%.*]] = udiv i32 [[TMP0:%.*]], [[COUNT:%.*]]
+; CHECK: vector.ph:
+; CHECK: exit:
+; CHECK: ret void
+;
+entry:
+ %cmp1 = icmp sgt i32 %lim, 0
+ br i1 %cmp1, label %loop1.preheader, label %exit
+
+loop1.preheader: ; preds = %entry
+ %cmp2 = icmp sgt i32 %count, 0
+ %cmp4 = icmp slt i32 %count, 8
+ br label %loop1.body
+
+loop1.body: ; preds = %loop1.inc, %loop1.preheader
+ %outer_i = phi i32 [ 0, %loop1.preheader ], [ %outer_i.1, %loop1.inc ]
+ %inx.1 = phi i32 [ 0, %loop1.preheader ], [ %inx.2, %loop1.inc ]
+ br i1 %cmp2, label %while.cond.preheader, label %loop1.inc
+
+while.cond.preheader: ; preds = %loop1.body
+ br i1 %cmp4, label %while.body, label %while.end
+
+while.body: ; preds = %while.body, %while.cond.preheader
+ %tmp = phi i32 [ %add3, %while.body ], [ %count, %while.cond.preheader ]
+ %result.1 = phi i32 [ %add, %while.body ], [ %val, %while.cond.preheader ]
+ %shr = ashr i32 %val, %tmp
+ %add = add nsw i32 %shr, %result.1
+ %add3 = add nsw i32 %tmp, %count
+ %cmp3 = icmp slt i32 %add3, 8
+ br i1 %cmp3, label %while.body, label %while.end
+
+while.end: ; preds = %while.body, %while.cond.preheader
+ %result.0.lcssa = phi i32 [ %val, %while.cond.preheader ], [ %add, %while.body ]
+ %conv = trunc i32 %result.0.lcssa to i8
+ %inc = add nsw i32 %inx.1, 1
+ %idxprom = sext i32 %inx.1 to i64
+ %arrayidx = getelementptr inbounds i8, i8* %ptr, i64 %idxprom
+ store i8 %conv, i8* %arrayidx, align 1
+ br label %loop1.inc
+
+loop1.inc: ; preds = %while.end, %loop1.body
+ %inx.2 = phi i32 [ %inc, %while.end ], [ %inx.1, %loop1.body ]
+ %outer_i.1 = add nuw nsw i32 %outer_i, 1
+ %exitcond = icmp eq i32 %outer_i.1, %lim
+ br i1 %exitcond, label %exit, label %loop1.body
+
+exit: ; preds = %loop1.inc, %entry
+ ret void
+}
+
+; These next tests are all based on the following source code, with slight
+; variations on the calculation of 'incr' (all of which are loop-invariant
+; divisions, but only some of which can be safely hoisted):
+;
+; uint32_t foo(uint32_t *ptr, uint32_t start1, uint32_t start2) {
+; uint32_t counter1, counter2;
+; uint32_t val = start1;
+; for (counter1 = 1; counter1 < 100; ++counter1) {
+; uint32_t index = 0;
+; val += ptr[index];
+; for (counter2 = start2; counter2 < 10; ++counter2) {
+; // Division is loop invariant, and denominator is guaranteed non-zero:
+; // Safe to hoist it out of the inner loop.
+; uint32_t incr = 16 / counter1;
+; index += incr;
+; val += ptr[index];
+; }
+; }
+; return val;
+; }
+
+; This version is as written above, where 'incr' is '16/counter1', and it is
+; guaranted that 'counter1' is always non-zero. So it is safe to hoist the
+; division from the inner loop to the preheader.
+;
+; Verify that the 'udiv' is hoisted to the preheader, and is not in the loop body.
+define i32 @NonZeroDivHoist(i32* nocapture readonly %ptr, i32 %start1, i32 %start2) {
+; INDVARCHECK-LABEL: @NonZeroDivHoist(
+; INDVARCHECK-NEXT: entry:
+; INDVARCHECK: for.body3.lr.ph:
+; INDVARCHECK-NEXT: [[TMP0:%.*]] = udiv i64 16, [[INDVARS_IV:%.*]]
+; INDVARCHECK-NEXT: br label [[FOR_BODY3:%.*]]
+; INDVARCHECK: for.body3:
+; INDVARCHECK-NOT: udiv
+; INDVARCHECK: for.end10:
+;
+entry:
+ br label %for.cond
+
+for.cond: ; preds = %for.end, %entry
+ %val.0 = phi i32 [ %start1, %entry ], [ %val.1.lcssa, %for.end ]
+ %counter1.0 = phi i32 [ 1, %entry ], [ %inc9, %for.end ]
+ %cmp = icmp ult i32 %counter1.0, 100
+ br i1 %cmp, label %for.body, label %for.end10
+
+for.body: ; preds = %for.cond
+ %tmp = load i32, i32* %ptr, align 4
+ %add = add i32 %tmp, %val.0
+ %cmp224 = icmp ult i32 %start2, 10
+ br i1 %cmp224, label %for.body3.lr.ph, label %for.end
+
+for.body3.lr.ph: ; preds = %for.body
+ br label %for.body3
+
+for.body3: ; preds = %for.body3, %for.body3.lr.ph
+ %index.027 = phi i32 [ 0, %for.body3.lr.ph ], [ %add4, %for.body3 ]
+ %val.126 = phi i32 [ %add, %for.body3.lr.ph ], [ %add7, %for.body3 ]
+ %counter2.025 = phi i32 [ %start2, %for.body3.lr.ph ], [ %inc, %for.body3 ]
+ %div = udiv i32 16, %counter1.0
+ %add4 = add i32 %div, %index.027
+ %idxprom5 = zext i32 %add4 to i64
+ %arrayidx6 = getelementptr inbounds i32, i32* %ptr, i64 %idxprom5
+ %tmp1 = load i32, i32* %arrayidx6, align 4
+ %add7 = add i32 %tmp1, %val.126
+ %inc = add i32 %counter2.025, 1
+ %cmp2 = icmp ult i32 %inc, 10
+ br i1 %cmp2, label %for.body3, label %for.cond1.for.end_crit_edge
+
+for.cond1.for.end_crit_edge: ; preds = %for.body3
+ %split = phi i32 [ %add7, %for.body3 ]
+ br label %for.end
+
+for.end: ; preds = %for.cond1.for.end_crit_edge, %for.body
+ %val.1.lcssa = phi i32 [ %split, %for.cond1.for.end_crit_edge ], [ %add, %for.body ]
+ %inc9 = add i32 %counter1.0, 1
+ br label %for.cond
+
+for.end10: ; preds = %for.cond
+ %val.0.lcssa = phi i32 [ %val.0, %for.cond ]
+ ret i32 %val.0.lcssa
+}
+
+; This version is identical to the above 'NonZeroDivHoist' case, except the
+; outer ('counter1') loop starts at the unknown value of 'start1' rather than 1,
+; and so it is illegal to hoist the division because if 'start1' is 0, hoisting
+; it would incorrectly cause a divide-by-zero trap.
+;
+; Verify that the 'udiv' is not hoisted to the preheader, and it remains in the
+; loop body.
+define i32 @ZeroDivNoHoist(i32* nocapture readonly %ptr, i32 %start1, i32 %start2) {
+; INDVARCHECK-LABEL: @ZeroDivNoHoist(
+; INDVARCHECK-NEXT: entry:
+; INDVARCHECK-NOT: udiv
+; INDVARCHECK: for.body3:
+; INDVARCHECK: [[TMP1:%.*]] = udiv i64 16, [[INDVARS_IV:%.*]]
+; INDVARCHECK: for.cond1.for.end_crit_edge:
+;
+entry:
+ br label %for.cond
+
+for.cond: ; preds = %for.end, %entry
+ %val.0 = phi i32 [ %start1, %entry ], [ %val.1.lcssa, %for.end ]
+ %counter1.0 = phi i32 [ %start1, %entry ], [ %inc9, %for.end ]
+ %cmp = icmp ult i32 %counter1.0, 100
+ br i1 %cmp, label %for.body, label %for.end10
+
+for.body: ; preds = %for.cond
+ %tmp = load i32, i32* %ptr, align 4
+ %add = add i32 %tmp, %val.0
+ %cmp224 = icmp ult i32 %start2, 10
+ br i1 %cmp224, label %for.body3.lr.ph, label %for.end
+
+for.body3.lr.ph: ; preds = %for.body
+ br label %for.body3
+
+for.body3: ; preds = %for.body3, %for.body3.lr.ph
+ %index.027 = phi i32 [ 0, %for.body3.lr.ph ], [ %add4, %for.body3 ]
+ %val.126 = phi i32 [ %add, %for.body3.lr.ph ], [ %add7, %for.body3 ]
+ %counter2.025 = phi i32 [ %start2, %for.body3.lr.ph ], [ %inc, %for.body3 ]
+ %div = udiv i32 16, %counter1.0
+ %add4 = add i32 %div, %index.027
+ %idxprom5 = zext i32 %add4 to i64
+ %arrayidx6 = getelementptr inbounds i32, i32* %ptr, i64 %idxprom5
+ %tmp1 = load i32, i32* %arrayidx6, align 4
+ %add7 = add i32 %tmp1, %val.126
+ %inc = add i32 %counter2.025, 1
+ %cmp2 = icmp ult i32 %inc, 10
+ br i1 %cmp2, label %for.body3, label %for.cond1.for.end_crit_edge
+
+for.cond1.for.end_crit_edge: ; preds = %for.body3
+ %split = phi i32 [ %add7, %for.body3 ]
+ br label %for.end
+
+for.end: ; preds = %for.cond1.for.end_crit_edge, %for.body
+ %val.1.lcssa = phi i32 [ %split, %for.cond1.for.end_crit_edge ], [ %add, %for.body ]
+ %inc9 = add i32 %counter1.0, 1
+ br label %for.cond
+
+for.end10: ; preds = %for.cond
+ %val.0.lcssa = phi i32 [ %val.0, %for.cond ]
+ ret i32 %val.0.lcssa
+}
+
+; This version is has a clearly safe division by a non-zero constant (16). The
+; division is transformed to a logical-shift-right of 4, and it is safely
+; hoisted.
+;
+; Verify that the division-operation is hoisted, and that it appears as a
+; right-shift ('lshr') rather than an explicit division.
+define i32 @DivBy16Hoist(i32* nocapture readonly %ptr, i32 %start1, i32 %start2) {
+; INDVARCHECK-LABEL: @DivBy16Hoist(
+; INDVARCHECK-NEXT: entry:
+; INDVARCHECK: for.cond:
+; INDVARCHECK: [[TMP1:%.*]] = lshr i64 [[INDVARS_IV:%.*]], 4
+; INDVARCHECK: for.body:
+; INDVARCHECK-NOT: lshr
+; INDVARCHECK-NOT: udiv
+; INDVARCHECK: for.end10:
+;
+entry:
+ br label %for.cond
+
+for.cond: ; preds = %for.end, %entry
+ %val.0 = phi i32 [ %start1, %entry ], [ %val.1.lcssa, %for.end ]
+ %counter1.0 = phi i32 [ %start1, %entry ], [ %inc9, %for.end ]
+ %cmp = icmp ult i32 %counter1.0, 100
+ br i1 %cmp, label %for.body, label %for.end10
+
+for.body: ; preds = %for.cond
+ %tmp = load i32, i32* %ptr, align 4
+ %add = add i32 %tmp, %val.0
+ %cmp224 = icmp ult i32 %start2, 10
+ br i1 %cmp224, label %for.body3.lr.ph, label %for.end
+
+for.body3.lr.ph: ; preds = %for.body
+ br label %for.body3
+
+for.body3: ; preds = %for.body3, %for.body3.lr.ph
+ %index.027 = phi i32 [ 0, %for.body3.lr.ph ], [ %add4, %for.body3 ]
+ %val.126 = phi i32 [ %add, %for.body3.lr.ph ], [ %add7, %for.body3 ]
+ %counter2.025 = phi i32 [ %start2, %for.body3.lr.ph ], [ %inc, %for.body3 ]
+ %div = udiv i32 %counter1.0, 16
+ %add4 = add i32 %div, %index.027
+ %idxprom5 = zext i32 %add4 to i64
+ %arrayidx6 = getelementptr inbounds i32, i32* %ptr, i64 %idxprom5
+ %tmp1 = load i32, i32* %arrayidx6, align 4
+ %add7 = add i32 %tmp1, %val.126
+ %inc = add i32 %counter2.025, 1
+ %cmp2 = icmp ult i32 %inc, 10
+ br i1 %cmp2, label %for.body3, label %for.cond1.for.end_crit_edge
+
+for.cond1.for.end_crit_edge: ; preds = %for.body3
+ %split = phi i32 [ %add7, %for.body3 ]
+ br label %for.end
+
+for.end: ; preds = %for.cond1.for.end_crit_edge, %for.body
+ %val.1.lcssa = phi i32 [ %split, %for.cond1.for.end_crit_edge ], [ %add, %for.body ]
+ %inc9 = add i32 %counter1.0, 1
+ br label %for.cond
+
+for.end10: ; preds = %for.cond
+ %val.0.lcssa = phi i32 [ %val.0, %for.cond ]
+ ret i32 %val.0.lcssa
+}
+
+; This version is has a clearly safe division by a non-zero constant (17). The
+; division is safely hoisted, as it was in the 'DivBy16Hoist' verison, but here
+; it remains a division, rather than being transformed to a right-shift.
+;
+; Verify that the division-operation is hoisted.
+define i32 @DivBy17Hoist(i32* nocapture readonly %ptr, i32 %start1, i32 %start2) {
+; INDVARCHECK-LABEL: @DivBy17Hoist(
+; INDVARCHECK-NEXT: entry:
+; INDVARCHECK: for.cond:
+; INDVARCHECK: [[TMP1:%.*]] = udiv i64 [[INDVARS_IV:%.*]], 17
+; INDVARCHECK: for.body:
+; INDVARCHECK-NOT: udiv
+; INDVARCHECK: for.end10:
+;
+entry:
+ br label %for.cond
+
+for.cond: ; preds = %for.end, %entry
+ %val.0 = phi i32 [ %start1, %entry ], [ %val.1.lcssa, %for.end ]
+ %counter1.0 = phi i32 [ %start1, %entry ], [ %inc9, %for.end ]
+ %cmp = icmp ult i32 %counter1.0, 100
+ br i1 %cmp, label %for.body, label %for.end10
+
+for.body: ; preds = %for.cond
+ %tmp = load i32, i32* %ptr, align 4
+ %add = add i32 %tmp, %val.0
+ %cmp224 = icmp ult i32 %start2, 10
+ br i1 %cmp224, label %for.body3.lr.ph, label %for.end
+
+for.body3.lr.ph: ; preds = %for.body
+ br label %for.body3
+
+for.body3: ; preds = %for.body3, %for.body3.lr.ph
+ %index.027 = phi i32 [ 0, %for.body3.lr.ph ], [ %add4, %for.body3 ]
+ %val.126 = phi i32 [ %add, %for.body3.lr.ph ], [ %add7, %for.body3 ]
+ %counter2.025 = phi i32 [ %start2, %for.body3.lr.ph ], [ %inc, %for.body3 ]
+ %div = udiv i32 %counter1.0, 17
+ %add4 = add i32 %div, %index.027
+ %idxprom5 = zext i32 %add4 to i64
+ %arrayidx6 = getelementptr inbounds i32, i32* %ptr, i64 %idxprom5
+ %tmp1 = load i32, i32* %arrayidx6, align 4
+ %add7 = add i32 %tmp1, %val.126
+ %inc = add i32 %counter2.025, 1
+ %cmp2 = icmp ult i32 %inc, 10
+ br i1 %cmp2, label %for.body3, label %for.cond1.for.end_crit_edge
+
+for.cond1.for.end_crit_edge: ; preds = %for.body3
+ %split = phi i32 [ %add7, %for.body3 ]
+ br label %for.end
+
+for.end: ; preds = %for.cond1.for.end_crit_edge, %for.body
+ %val.1.lcssa = phi i32 [ %split, %for.cond1.for.end_crit_edge ], [ %add, %for.body ]
+ %inc9 = add i32 %counter1.0, 1
+ br label %for.cond
+
+for.end10: ; preds = %for.cond
+ %val.0.lcssa = phi i32 [ %val.0, %for.cond ]
+ ret i32 %val.0.lcssa
+}