Index: lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp =================================================================== --- lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp +++ lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp @@ -1085,7 +1085,8 @@ } auto Clamp = [this, Smallest, Greatest, IsSignedPredicate](const SCEV *S) { - return IsSignedPredicate + bool MaybeNegativeValues = IsSignedPredicate || !SE.isKnownNonNegative(S); + return MaybeNegativeValues ? SE.getSMaxExpr(Smallest, SE.getSMinExpr(Greatest, S)) : SE.getUMaxExpr(Smallest, SE.getUMinExpr(Greatest, S)); }; Index: test/Transforms/IRCE/clamp.ll =================================================================== --- /dev/null +++ test/Transforms/IRCE/clamp.ll @@ -0,0 +1,61 @@ +; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s + +; The test demonstrates that incorrect behavior of Clamp may lead to incorrect +; calculation of post-loop exit condition. + +; CHECK: irce: in function test: constrained Loop at depth 1 containing: %loop
,%in_bounds,%not_zero + +define void @test() { +entry: + %indvars.iv.next467 = add nuw nsw i64 2, 1 + %length.i167 = load i32, i32 addrspace(1)* undef, align 8 + %tmp21 = zext i32 %length.i167 to i64 + %tmp34 = load atomic i32, i32 addrspace(1)* undef unordered, align 4 + %tmp35 = add i32 %tmp34, -9581 + %tmp36 = icmp ugt i32 %length.i167, 1 + br i1 %tmp36, label %preheader, label %exit + +exit: ; preds = %in_bounds, %loop, %not_zero, %entry + ret void + +preheader: ; preds = %entry +; CHECK: preheader: +; CHECK-NEXT: %length_gep.i146 = getelementptr inbounds i8, i8 addrspace(1)* undef, i64 8 +; CHECK-NEXT: %length_gep_typed.i147 = bitcast i8 addrspace(1)* undef to i32 addrspace(1)* +; CHECK-NEXT: %tmp43 = icmp ult i64 %indvars.iv.next467, %tmp21 +; CHECK-NEXT: br i1 false, label %loop.preheader, label %main.pseudo.exit + + %length_gep.i146 = getelementptr inbounds i8, i8 addrspace(1)* undef, i64 8 + %length_gep_typed.i147 = bitcast i8 addrspace(1)* undef to i32 addrspace(1)* + %tmp43 = icmp ult i64 %indvars.iv.next467, %tmp21 + br label %loop + +not_zero: ; preds = %in_bounds +; CHECK: not_zero: +; CHECK: %tmp56 = icmp ult i64 %indvars.iv.next, %tmp21 +; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i64 %indvars.iv.next, 1 +; CHECK-NEXT: br i1 [[COND]], label %loop, label %main.exit.selector + + %tmp51 = trunc i64 %indvars.iv.next to i32 + %tmp53 = mul i32 %tmp51, %tmp51 + %tmp54 = add i32 %tmp53, -9582 + %tmp55 = add i32 %tmp54, %tmp62 + %tmp56 = icmp ult i64 %indvars.iv.next, %tmp21 + br i1 %tmp56, label %loop, label %exit + +loop: ; preds = %not_zero, %preheader + %tmp62 = phi i32 [ 1, %preheader ], [ %tmp55, %not_zero ] + %indvars.iv750 = phi i64 [ 1, %preheader ], [ %indvars.iv.next, %not_zero ] + %length.i148 = load i32, i32 addrspace(1)* %length_gep_typed.i147, align 8 + %tmp68 = zext i32 %length.i148 to i64 + %tmp97 = icmp ult i64 2, %tmp68 + %or.cond = and i1 %tmp43, %tmp97 + %tmp99 = icmp ult i64 %indvars.iv750, %tmp21 + %or.cond1 = and i1 %or.cond, %tmp99 + br i1 %or.cond1, label %in_bounds, label %exit + +in_bounds: ; preds = %loop + %indvars.iv.next = add nuw nsw i64 %indvars.iv750, 3 + %tmp107 = icmp ult i64 %indvars.iv.next, 2 + br i1 %tmp107, label %not_zero, label %exit +}