Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -5845,7 +5845,10 @@
 
     // See if ValueTracking can give us a useful range.
     const DataLayout &DL = getDataLayout();
-    KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
+    const Instruction *CxtI = dyn_cast<Instruction>(U->getValue());
+    if (!CxtI)
+      CxtI = &*(F.getEntryBlock().begin());
+    KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, CxtI, &DT);
     if (Known.getBitWidth() != BitWidth)
       Known = Known.zextOrTrunc(BitWidth);
     // If Known does not result in full-set, intersect with it.
@@ -5856,7 +5859,7 @@
 
     // ValueTracking may be able to compute a tighter result for the number of
     // sign bits than for the value of those sign bits.
-    unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
+    unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, CxtI, &DT);
     // If the pointer size is larger than the index size type, this can cause
     // NS to be larger than BitWidth. So compensate for this.
     if (U->getType()->isPointerTy()) {
Index: llvm/test/Analysis/ScalarEvolution/ranges.ll
===================================================================
--- llvm/test/Analysis/ScalarEvolution/ranges.ll
+++ llvm/test/Analysis/ScalarEvolution/ranges.ll
@@ -15,9 +15,9 @@
 ; CHECK-NEXT:    --> %ashr U: [0,1) S: [0,1)
 ; CHECK-NEXT:  Determining loop execution counts for: @ashr
 ;
+  %ashr = ashr i32 %a, 31
   %pos = icmp sge i32 %a, 0
   call void @llvm.assume(i1 %pos)
-  %ashr = ashr i32 %a, 31
   ret i32 %ashr
 }
 
@@ -28,9 +28,9 @@
 ; CHECK-NEXT:    --> (4 * %a) U: [0,-3) S: [-2147483648,2147483645)
 ; CHECK-NEXT:  Determining loop execution counts for: @shl
 ;
+  %res = shl i32 %a, 2
   %pos = icmp slt i32 %a, 1024
   call void @llvm.assume(i1 %pos)
-  %res = shl i32 %a, 2
   ret i32 %res
 }
 
@@ -38,12 +38,12 @@
 ; CHECK-LABEL: 'lshr'
 ; CHECK-NEXT:  Classifying expressions for: @lshr
 ; CHECK-NEXT:    %res = lshr i32 %a, 31
-; CHECK-NEXT:    --> (%a /u -2147483648) U: [0,2) S: [0,2)
+; CHECK-NEXT:    --> (%a /u -2147483648) U: [0,1) S: [0,1)
 ; CHECK-NEXT:  Determining loop execution counts for: @lshr
 ;
+  %res = lshr i32 %a, 31
   %pos = icmp sge i32 %a, 0
   call void @llvm.assume(i1 %pos)
-  %res = lshr i32 %a, 31
   ret i32 %res
 }
 
@@ -52,37 +52,37 @@
 ; CHECK-LABEL: 'udiv'
 ; CHECK-NEXT:  Classifying expressions for: @udiv
 ; CHECK-NEXT:    %res = udiv i32 %a, -2147483648
-; CHECK-NEXT:    --> (%a /u -2147483648) U: [0,2) S: [0,2)
+; CHECK-NEXT:    --> (%a /u -2147483648) U: [0,1) S: [0,1)
 ; CHECK-NEXT:  Determining loop execution counts for: @udiv
 ;
+  %res = udiv i32 %a, 2147483648
   %pos = icmp sge i32 %a, 0
   call void @llvm.assume(i1 %pos)
-  %res = udiv i32 %a, 2147483648
   ret i32 %res
 }
 
-define i64 @sext(i32 %a) {
+define i64 @sext(i8 %a) {
 ; CHECK-LABEL: 'sext'
 ; CHECK-NEXT:  Classifying expressions for: @sext
-; CHECK-NEXT:    %res = sext i32 %a to i64
-; CHECK-NEXT:    --> (sext i32 %a to i64) U: [-2147483648,2147483648) S: [-2147483648,2147483648)
+; CHECK-NEXT:    %res = sext i8 %a to i64
+; CHECK-NEXT:    --> (zext i8 %a to i64) U: [0,128) S: [0,128)
 ; CHECK-NEXT:  Determining loop execution counts for: @sext
 ;
-  %pos = icmp sge i32 %a, 0
+  %res = sext i8 %a to i64
+  %pos = icmp sge i8 %a, 0
   call void @llvm.assume(i1 %pos)
-  %res = sext i32 %a to i64
   ret i64 %res
 }
 
-define i64 @zext(i32 %a) {
+define i64 @zext(i8 %a) {
 ; CHECK-LABEL: 'zext'
 ; CHECK-NEXT:  Classifying expressions for: @zext
-; CHECK-NEXT:    %res = zext i32 %a to i64
-; CHECK-NEXT:    --> (zext i32 %a to i64) U: [0,4294967296) S: [0,4294967296)
+; CHECK-NEXT:    %res = zext i8 %a to i64
+; CHECK-NEXT:    --> (zext i8 %a to i64) U: [0,128) S: [0,128)
 ; CHECK-NEXT:  Determining loop execution counts for: @zext
 ;
-  %pos = icmp sge i32 %a, 0
+  %res = zext i8 %a to i64
+  %pos = icmp sge i8 %a, 0
   call void @llvm.assume(i1 %pos)
-  %res = zext i32 %a to i64
   ret i64 %res
 }