--- /dev/null
+; RUN: opt < %s -indvars -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+; PR25372
+; We can compute the expression of %phi0 and that is a SCEV
+; constant. However, instcombine can't deduce this, so we can
+; potentially end up trying to handle a constant when replacing
+; congruent IVs.
+
+; CHECK-LABEL: crash
+define void @crash() {
+entry:
+ br i1 false, label %not_taken, label %pre
+
+not_taken:
+ br label %pre
+
+pre:
+; %phi0.pre and %phi1.pre are evaluated by SCEV to constant 0.
+ %phi0.pre = phi i32 [ 0, %entry ], [ 2, %not_taken ]
+ %phi1.pre = phi i32 [ 0, %entry ], [ 1, %not_taken ]
+ br label %loop
+
+loop:
+; %phi0 and %phi1 are evaluated by SCEV to constant 0.
+ %phi0 = phi i32 [ 0, %loop ], [ %phi0.pre, %pre ]
+ %phi1 = phi i32 [ 0, %loop ], [ %phi1.pre, %pre ]
+ br i1 undef, label %exit, label %loop
+
+exit:
+ ret void
+}