const SCEV *Start = IV->getStart();
const SCEV *End = RHS;
- if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS))
- End = IsSigned ? getSMinExpr(RHS, Start) : getUMinExpr(RHS, Start);
+ if (!isLoopEntryGuardedByCond(L, Cond, getAddExpr(Start, Stride), RHS)) {
+ // If we know that Start >= RHS in the context of loop, then we know that
+ // min(RHS, Start) = RHS at this point.
+ if (isLoopEntryGuardedByCond(
+ L, IsSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE, Start, RHS))
+ End = RHS;
+ else
+ End = IsSigned ? getSMinExpr(RHS, Start) : getUMinExpr(RHS, Start);
+ }
const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false);
; CHECK-LABEL: 'reverse_loop'
; CHECK-NEXT: Classifying expressions for: @reverse_loop
; CHECK-NEXT: %i.011 = phi i32 [ %n, %for.body.lr.ph ], [ %dec, %for.body ]
-; CHECK-NEXT: --> {%n,+,-1}<nsw><%for.body> U: full-set S: full-set Exits: (0 smin %n) LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: --> {%n,+,-1}<nsw><%for.body> U: full-set S: full-set Exits: 0 LoopDispositions: { %for.body: Computable }
; CHECK-NEXT: %dec = add nsw i32 %i.011, -1
-; CHECK-NEXT: --> {(-1 + %n),+,-1}<nw><%for.body> U: full-set S: full-set Exits: (-1 + (0 smin %n)) LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: --> {(-1 + %n),+,-1}<nw><%for.body> U: full-set S: full-set Exits: -1 LoopDispositions: { %for.body: Computable }
; CHECK-NEXT: Determining loop execution counts for: @reverse_loop
-; CHECK-NEXT: Loop %for.body: backedge-taken count is ((-1 * (0 smin %n)) + %n)
+; CHECK-NEXT: Loop %for.body: backedge-taken count is %n
; CHECK-NEXT: Loop %for.body: max backedge-taken count is 2147483647
-; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is ((-1 * (0 smin %n)) + %n)
+; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is %n
; CHECK-NEXT: Predicates:
; CHECK: Loop %for.body: Trip multiple is 1
;
; CHECK-GUARD: br i1 %cmp4, label %while.end, label %while.body.preheader
; CHECK-GUARD: while.body.preheader:
; CHECK-GUARD: [[ADD:%[^ ]+]] = add i32 %i, 1
-; CHECK-GUARD: [[SEL:%[^ ]+]] = icmp slt i32 %N, %i
-; CHECK-GUARD: [[MIN:%[^ ]+]] = select i1 [[SEL]], i32 %N, i32 %i
-; CHECK-GUARD: [[COUNT:%[^ ]+]] = sub i32 [[ADD]], [[MIN]]
+; CHECK-GUARD: [[COUNT:%[^ ]+]] = sub i32 [[ADD]], %N
; CHECK-GUARD: call void @llvm.set.loop.iterations.i32(i32 [[COUNT]])
; CHECK-GUARD: br label %while.body
; CHECK-LABEL: while_gte
; CHECK: while.body.preheader:
; CHECK: [[ADD:%[^ ]+]] = add i32 %i, 1
-; CHECK: [[SEL:%[^ ]+]] = icmp slt i32 %N, %i
-; CHECK: [[MIN:%[^ ]+]] = select i1 [[SEL]], i32 %N, i32 %i
-; CHECK: [[COUNT:%[^ ]+]] = sub i32 [[ADD]], [[MIN]]
+; CHECK: [[COUNT:%[^ ]+]] = sub i32 [[ADD]], %N
; CHECK: call void @llvm.set.loop.iterations.i32(i32 [[COUNT]])
; CHECK: br label %while.body