if (!Cmp.isEquality() && DivIsSigned != Cmp.isSigned())
return nullptr;
- // These constant divides should already be folded in InstSimplify.
- assert(*C2 != 0 && "The ProdOV computation fails on divide by zero.");
- assert(*C2 != 1 && "Funny cases with INT_MIN will fail.");
-
- // This constant divide should already be folded in InstCombine.
- assert(!(DivIsSigned && C2->isAllOnesValue()) &&
- "The overflow computation will fail.");
+ // The ProdOV computation fails on divide by 0 and divide by -1. Cases with
+ // INT_MIN will also fail if the divisor is 1. Although folds of all these
+ // division-by-constant cases should be present, we can not assert that they
+ // have happened before we reach this icmp instruction.
+ if (*C2 == 0 || *C2 == 1 || (DivIsSigned && C2->isAllOnesValue()))
+ return nullptr;
// TODO: We could do all of the computations below using APInt.
Constant *CmpRHS = cast<Constant>(Cmp.getOperand(1));
--- /dev/null
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; PR30281 - https://llvm.org/bugs/show_bug.cgi?id=30281
+
+; All of these tests contain foldable division-by-constant instructions, but we
+; can't assert that those folds have occurred before we process the later icmp.
+
+define i32 @icmp_div(i16 %a, i16 %c) {
+; CHECK-LABEL: @icmp_div(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i16 %a, 0
+; CHECK-NEXT: br i1 [[TOBOOL]], label %then, label %exit
+; CHECK: then:
+; CHECK-NEXT: [[NOT_CMP:%.*]] = icmp eq i16 %c, 0
+; CHECK-NEXT: [[PHITMP1:%.*]] = sext i1 [[NOT_CMP]] to i32
+; CHECK-NEXT: br label %exit
+; CHECK: exit:
+; CHECK-NEXT: [[PHI:%.*]] = phi i32 [ -1, %entry ], [ [[PHI:%.*]]tmp1, %then ]
+; CHECK-NEXT: ret i32 [[PHI]]
+;
+entry:
+ %tobool = icmp eq i16 %a, 0
+ br i1 %tobool, label %then, label %exit
+
+then:
+ %div = sdiv i16 %c, -1
+ %cmp = icmp ne i16 %div, 0
+ br label %exit
+
+exit:
+ %phi = phi i1 [ false, %entry ], [ %cmp, %then ]
+ %zext = zext i1 %phi to i32
+ %add = add nsw i32 %zext, -1
+ ret i32 %add
+}
+
+define i32 @icmp_div2(i16 %a, i16 %c) {
+; CHECK-LABEL: @icmp_div2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i16 %a, 0
+; CHECK-NEXT: br i1 [[TOBOOL]], label %then, label %exit
+; CHECK: then:
+; CHECK-NEXT: br label %exit
+; CHECK: exit:
+; CHECK-NEXT: [[PHI:%.*]] = phi i32 [ -1, %entry ], [ 0, %then ]
+; CHECK-NEXT: ret i32 [[PHI]]
+;
+entry:
+ %tobool = icmp eq i16 %a, 0
+ br i1 %tobool, label %then, label %exit
+
+then:
+ %div = sdiv i16 %c, 0
+ %cmp = icmp ne i16 %div, 0
+ br label %exit
+
+exit:
+ %phi = phi i1 [ false, %entry ], [ %cmp, %then ]
+ %zext = zext i1 %phi to i32
+ %add = add nsw i32 %zext, -1
+ ret i32 %add
+}
+
+define i32 @icmp_div3(i16 %a, i16 %c) {
+; CHECK-LABEL: @icmp_div3(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i16 %a, 0
+; CHECK-NEXT: br i1 [[TOBOOL]], label %then, label %exit
+; CHECK: then:
+; CHECK-NEXT: [[NOT_CMP:%.*]] = icmp eq i16 %c, 0
+; CHECK-NEXT: [[PHITMP1:%.*]] = sext i1 [[NOT_CMP]] to i32
+; CHECK-NEXT: br label %exit
+; CHECK: exit:
+; CHECK-NEXT: [[PHI:%.*]] = phi i32 [ -1, %entry ], [ [[PHI:%.*]]tmp1, %then ]
+; CHECK-NEXT: ret i32 [[PHI]]
+;
+entry:
+ %tobool = icmp eq i16 %a, 0
+ br i1 %tobool, label %then, label %exit
+
+then:
+ %div = sdiv i16 %c, 1
+ %cmp = icmp ne i16 %div, 0
+ br label %exit
+
+exit:
+ %phi = phi i1 [ false, %entry ], [ %cmp, %then ]
+ %zext = zext i1 %phi to i32
+ %add = add nsw i32 %zext, -1
+ ret i32 %add
+}
+