Teach SCEV to handle more cases of 'and X, CST', specifically where CST is any number of contiguous 1 bits in a row, with any number of leading and trailing 0 bits.

Unfortunately, this in turn led to some lower quality SCEVs due to some different paths through expression simplification, so add getUDivExactExpr and use it. This fixes all instances of the problems that I found, but we can make that function smarter as necessary.

Merge test "xor-and.ll" into "and-xor.ll" since I needed to update it anyways. Test 'nsw-offset.ll' analyzes a little deeper, %n now gets a scev in terms of %no instead of a SCEVUnknown.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200203 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 1 deletions

diff --git a/test/Analysis/ScalarEvolution/and-xor.ll b/test/Analysis/ScalarEvolution/and-xor.ll
index 404ab91e26..ad636da4d4 100644
--- a/test/Analysis/ScalarEvolution/and-xor.ll
+++ b/test/Analysis/ScalarEvolution/and-xor.ll
@@ -1,11 +1,27 @@
 ; RUN: opt < %s -scalar-evolution -analyze | FileCheck %s
 
+; CHECK-LABEL: @test1
 ; CHECK: -->  (zext
 ; CHECK: -->  (zext
 ; CHECK-NOT: -->  (zext
 
-define i32 @foo(i32 %x) {
+define i32 @test1(i32 %x) {
   %n = and i32 %x, 255
   %y = xor i32 %n, 255
   ret i32 %y
 }
+
+; ScalarEvolution shouldn't try to analyze %z into something like
+;   -->  (zext i4 (-1 + (-1 * (trunc i64 (8 * %x) to i4))) to i64)
+; or
+;   -->  (8 * (zext i1 (trunc i64 ((8 * %x) /u 8) to i1) to i64))
+
+; CHECK-LABEL: @test2
+; CHECK: -->  (8 * (zext i1 (trunc i64 %x to i1) to i64))
+
+define i64 @test2(i64 %x) {
+  %a = shl i64 %x, 3
+  %t = and i64 %a, 8
+  %z = xor i64 %t, 8
+  ret i64 %z
+}