: ICmpInst::ICMP_ULT;
const SCEV *Start = IV->getStart();
const SCEV *End = RHS;
- if (!isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS))
- End = IsSigned ? getSMaxExpr(RHS, Start)
- : getUMaxExpr(RHS, Start);
+ if (!isLoopEntryGuardedByCond(L, Cond, getMinusSCEV(Start, Stride), RHS)) {
+ const SCEV *Diff = getMinusSCEV(RHS, Start);
+ // If we have NoWrap set, then we can assume that the increment won't
+ // overflow, in which case if RHS - Start is a constant, we don't need to
+ // do a max operation since we can just figure it out statically
+ if (NoWrap && isa<SCEVConstant>(Diff)) {
+ APInt D = dyn_cast<const SCEVConstant>(Diff)->getValue()->getValue();
+ if (D.isNegative())
+ End = Start;
+ } else
+ End = IsSigned ? getSMaxExpr(RHS, Start)
+ : getUMaxExpr(RHS, Start);
+ }
const SCEV *BECount = computeBECount(getMinusSCEV(End, Start), Stride, false);
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)) {
+ const SCEV *Diff = getMinusSCEV(RHS, Start);
+ // If we have NoWrap set, then we can assume that the increment won't
+ // overflow, in which case if RHS - Start is a constant, we don't need to
+ // do a max operation since we can just figure it out statically
+ if (NoWrap && isa<SCEVConstant>(Diff)) {
+ APInt D = dyn_cast<const SCEVConstant>(Diff)->getValue()->getValue();
+ if (!D.isNegative())
+ End = Start;
+ } else
+ End = IsSigned ? getSMinExpr(RHS, Start)
+ : getUMinExpr(RHS, Start);
+ }
const SCEV *BECount = computeBECount(getMinusSCEV(Start, End), Stride, false);
ret i32 %result
}
-; TODO: This could fold down to '1'
; CHECK-LABEL: PR12375
-; CHECK: --> {(4 + %arg),+,4}<nuw><%bb1> Exits: (4 + (4 * ((-1 + (-1 * %arg) + ((4 + %arg) umax (8 + %arg)<nsw>)) /u 4)) + %arg)
+; CHECK: --> {(4 + %arg),+,4}<nuw><%bb1> Exits: (8 + %arg)<nsw>
define i32 @PR12375(i32* readnone %arg) {
bb:
%tmp = getelementptr inbounds i32* %arg, i64 2
bb5: ; preds = %bb2
ret void
}
+
+declare void @f(i32)
+
+; CHECK-LABEL: nswnowrap
+; CHECK: --> {(1 + %v),+,1}<nsw><%for.body> Exits: (2 + %v)
+define void @nswnowrap(i32 %v) {
+entry:
+ %add = add nsw i32 %v, 1
+ br label %for.body
+
+for.body:
+ %i.04 = phi i32 [ %v, %entry ], [ %inc, %for.body ]
+ %inc = add nsw i32 %i.04, 1
+ tail call void @f(i32 %i.04)
+ %cmp = icmp slt i32 %i.04, %add
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end:
+ ret void
+}
--- /dev/null
+; RUN: opt -loop-unroll -S %s | FileCheck %s
+
+; extern void f(int);
+; void test1(int v) {
+; for (int i=v; i<=v+1; ++i)
+; f(i);
+; }
+;
+; We can use the nsw information to see that the tripcount will be 2, so the
+; loop should be unrolled as this is always beneficial
+
+declare void @f(i32)
+
+; CHECK-LABEL: @test1
+define void @test1(i32 %v) {
+entry:
+ %add = add nsw i32 %v, 1
+ br label %for.body
+
+for.body:
+ %i.04 = phi i32 [ %v, %entry ], [ %inc, %for.body ]
+ tail call void @f(i32 %i.04)
+ %inc = add nsw i32 %i.04, 1
+ %cmp = icmp slt i32 %i.04, %add
+ br i1 %cmp, label %for.body, label %for.end
+
+; CHECK: call void @f
+; CHECK-NOT: br i1
+; CHECK: call void @f
+for.end:
+ ret void
+}