This patch implements optimization as mentioned in PR19753: Optimize comparisons with "ashr/lshr exact" of a constanst.

It handles the errors which were seen in PR19958 where wrong code was being emitted due to earlier patch.
Added code for lshr as well as non-exact right shifts.

It implements : 
(icmp eq/ne (ashr/lshr const2, A), const1)" ->
(icmp eq/ne A, Log2(const2/const1)) ->
(icmp eq/ne A, Log2(const2) - Log2(const1))

Differential Revision: http://reviews.llvm.org/D4068
 

llvm-svn: 213678

1 files changed, 677 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/icmp-shr.ll b/llvm/test/Transforms/InstCombine/icmp-shr.ll
new file mode 100644
index 00000000000..36490e5d10a
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/icmp-shr.ll
@@ -0,0 +1,677 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-p1:16:16:16-p2:32:32:32-p3:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+
+; CHECK-LABEL: @exact_lshr_eq_both_zero
+; CHECK-NEXT: ret i1 true
+define i1 @exact_lshr_eq_both_zero(i8 %a) {
+ %shr = lshr exact i8 0, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_both_zero
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_eq_both_zero(i8 %a) {
+ %shr = ashr exact i8 0, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq_both_zero
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_lshr_eq_both_zero(i8 %a) {
+ %shr = lshr i8 0, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq_both_zero
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_ashr_eq_both_zero(i8 %a) {
+ %shr = ashr i8 0, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_both_zero
+; CHECK-NEXT: ret i1 false
+define i1 @exact_lshr_ne_both_zero(i8 %a) {
+ %shr = lshr exact i8 0, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_both_zero
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_ne_both_zero(i8 %a) {
+ %shr = ashr exact i8 0, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne_both_zero
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_lshr_ne_both_zero(i8 %a) {
+ %shr = lshr i8 0, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne_both_zero
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_ashr_ne_both_zero(i8 %a) {
+ %shr = ashr i8 0, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_last_zero
+; CHECK-NEXT: ret i1 false
+define i1 @exact_lshr_eq_last_zero(i8 %a) {
+ %shr = lshr exact i8 128, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_last_zero
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_eq_last_zero(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_last_zero
+; CHECK-NEXT: ret i1 true
+define i1 @exact_lshr_ne_last_zero(i8 %a) {
+ %shr = lshr exact i8 128, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_last_zero
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_ne_last_zero(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq_last_zero
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_lshr_eq_last_zero(i8 %a) {
+ %shr = lshr i8 128, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq_last_zero
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_ashr_eq_last_zero(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne_last_zero
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_lshr_ne_last_zero(i8 %a) {
+ %shr = lshr i8 128, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne_last_zero
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_ashr_ne_last_zero(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_eq_msb_low_last_zero
+; CHECK-NEXT: icmp ugt i8 %a, 6
+define i1 @lshr_eq_msb_low_last_zero(i8 %a) {
+ %shr = lshr i8 127, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_eq_msb_low_second_zero
+; CHECK-NEXT: icmp ugt i8 %a, 6
+define i1 @ashr_eq_msb_low_second_zero(i8 %a) {
+ %shr = ashr i8 127, %a
+ %cmp = icmp eq i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_ne_msb_low_last_zero
+; CHECK-NEXT: icmp ult i8 %a, 7
+define i1 @lshr_ne_msb_low_last_zero(i8 %a) {
+ %shr = lshr i8 127, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_ne_msb_low_second_zero
+; CHECK-NEXT: icmp ult i8 %a, 7
+define i1 @ashr_ne_msb_low_second_zero(i8 %a) {
+ %shr = ashr i8 127, %a
+ %cmp = icmp ne i8 %shr, 0
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_eq_first_zero
+; CHECK-NEXT: ret i1 false
+define i1 @lshr_eq_first_zero(i8 %a) {
+ %shr = lshr i8 0, %a
+ %cmp = icmp eq i8 %shr, 2
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_eq_first_zero
+; CHECK-NEXT: ret i1 false
+define i1 @ashr_eq_first_zero(i8 %a) {
+ %shr = ashr i8 0, %a
+ %cmp = icmp eq i8 %shr, 2
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_ne_first_zero
+; CHECK-NEXT: ret i1 true
+define i1 @lshr_ne_first_zero(i8 %a) {
+ %shr = lshr i8 0, %a
+ %cmp = icmp ne i8 %shr, 2
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_ne_first_zero
+; CHECK-NEXT: ret i1 true
+define i1 @ashr_ne_first_zero(i8 %a) {
+ %shr = ashr i8 0, %a
+ %cmp = icmp ne i8 %shr, 2
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_eq_both_minus1
+; CHECK-NEXT: ret i1 true
+define i1 @ashr_eq_both_minus1(i8 %a) {
+ %shr = ashr i8 -1, %a
+ %cmp = icmp eq i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_ne_both_minus1
+; CHECK-NEXT: ret i1 false
+define i1 @ashr_ne_both_minus1(i8 %a) {
+ %shr = ashr i8 -1, %a
+ %cmp = icmp ne i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_both_minus1
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_eq_both_minus1(i8 %a) {
+ %shr = ashr exact i8 -1, %a
+ %cmp = icmp eq i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_both_minus1
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_ne_both_minus1(i8 %a) {
+ %shr = ashr exact i8 -1, %a
+ %cmp = icmp ne i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_eq_both_equal
+; CHECK-NEXT: icmp eq i8 %a, 0
+define i1 @ashr_eq_both_equal(i8 %a) {
+ %shr = ashr i8 128, %a
+ %cmp = icmp eq i8 %shr, 128
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_ne_both_equal
+; CHECK-NEXT: icmp ne i8 %a, 0
+define i1 @ashr_ne_both_equal(i8 %a) {
+ %shr = ashr i8 128, %a
+ %cmp = icmp ne i8 %shr, 128
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_eq_both_equal
+; CHECK-NEXT: icmp eq i8 %a, 0
+define i1 @lshr_eq_both_equal(i8 %a) {
+ %shr = lshr i8 127, %a
+ %cmp = icmp eq i8 %shr, 127
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_ne_both_equal
+; CHECK-NEXT: icmp ne i8 %a, 0
+define i1 @lshr_ne_both_equal(i8 %a) {
+ %shr = lshr i8 127, %a
+ %cmp = icmp ne i8 %shr, 127
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_both_equal
+; CHECK-NEXT: icmp eq i8 %a, 0
+define i1 @exact_ashr_eq_both_equal(i8 %a) {
+ %shr = ashr exact i8 128, %a
+ %cmp = icmp eq i8 %shr, 128
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_both_equal
+; CHECK-NEXT: icmp ne i8 %a, 0
+define i1 @exact_ashr_ne_both_equal(i8 %a) {
+ %shr = ashr exact i8 128, %a
+ %cmp = icmp ne i8 %shr, 128
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_both_equal
+; CHECK-NEXT: icmp eq i8 %a, 0
+define i1 @exact_lshr_eq_both_equal(i8 %a) {
+ %shr = lshr exact i8 126, %a
+ %cmp = icmp eq i8 %shr, 126
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_both_equal
+; CHECK-NEXT: icmp ne i8 %a, 0
+define i1 @exact_lshr_ne_both_equal(i8 %a) {
+ %shr = lshr exact i8 126, %a
+ %cmp = icmp ne i8 %shr, 126
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_opposite_msb
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_eq_opposite_msb(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp eq i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_eq_opposite_msb
+; CHECK-NEXT: ret i1 false
+define i1 @ashr_eq_opposite_msb(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp eq i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_opposite_msb
+; CHECK-NEXT: icmp eq i8 %a, 7
+define i1 @exact_lshr_eq_opposite_msb(i8 %a) {
+ %shr = lshr exact i8 -128, %a
+ %cmp = icmp eq i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_eq_opposite_msb
+; CHECK-NEXT: icmp eq i8 %a, 7
+define i1 @lshr_eq_opposite_msb(i8 %a) {
+ %shr = lshr i8 -128, %a
+ %cmp = icmp eq i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_opposite_msb
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_ne_opposite_msb(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp ne i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @ashr_ne_opposite_msb
+; CHECK-NEXT: ret i1 true
+define i1 @ashr_ne_opposite_msb(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp ne i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_opposite_msb
+; CHECK-NEXT: icmp ne i8 %a, 7
+define i1 @exact_lshr_ne_opposite_msb(i8 %a) {
+ %shr = lshr exact i8 -128, %a
+ %cmp = icmp ne i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @lshr_ne_opposite_msb
+; CHECK-NEXT: icmp ne i8 %a, 7
+define i1 @lshr_ne_opposite_msb(i8 %a) {
+ %shr = lshr i8 -128, %a
+ %cmp = icmp ne i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_shift_gt
+; CHECK-NEXT : ret i1 false
+define i1 @exact_ashr_eq_shift_gt(i8 %a) {
+ %shr = ashr exact i8 -2, %a
+ %cmp = icmp eq i8 %shr, -8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_shift_gt
+; CHECK-NEXT : ret i1 true
+define i1 @exact_ashr_ne_shift_gt(i8 %a) {
+ %shr = ashr exact i8 -2, %a
+ %cmp = icmp ne i8 %shr, -8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq_shift_gt
+; CHECK-NEXT : ret i1 false
+define i1 @nonexact_ashr_eq_shift_gt(i8 %a) {
+ %shr = ashr i8 -2, %a
+ %cmp = icmp eq i8 %shr, -8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne_shift_gt
+; CHECK-NEXT : ret i1 true
+define i1 @nonexact_ashr_ne_shift_gt(i8 %a) {
+ %shr = ashr i8 -2, %a
+ %cmp = icmp ne i8 %shr, -8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_shift_gt
+; CHECK-NEXT: ret i1 false
+define i1 @exact_lshr_eq_shift_gt(i8 %a) {
+ %shr = lshr exact i8 2, %a
+ %cmp = icmp eq i8 %shr, 8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_shift_gt
+; CHECK-NEXT: ret i1 true
+define i1 @exact_lshr_ne_shift_gt(i8 %a) {
+ %shr = lshr exact i8 2, %a
+ %cmp = icmp ne i8 %shr, 8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq_shift_gt
+; CHECK-NEXT : ret i1 false
+define i1 @nonexact_lshr_eq_shift_gt(i8 %a) {
+ %shr = lshr i8 2, %a
+ %cmp = icmp eq i8 %shr, 8
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne_shift_gt
+; CHECK-NEXT : ret i1 true
+define i1 @nonexact_lshr_ne_shift_gt(i8 %a) {
+ %shr = ashr i8 2, %a
+ %cmp = icmp ne i8 %shr, 8
+ ret i1 %cmp
+}
+
+
+
+; CHECK-LABEL: @exact_ashr_eq
+; CHECK-NEXT: icmp eq i8 %a, 7
+define i1 @exact_ashr_eq(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp eq i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne
+; CHECK-NEXT: icmp ne i8 %a, 7
+define i1 @exact_ashr_ne(i8 %a) {
+ %shr = ashr exact i8 -128, %a
+ %cmp = icmp ne i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq
+; CHECK-NEXT: icmp eq i8 %a, 2
+define i1 @exact_lshr_eq(i8 %a) {
+ %shr = lshr exact i8 4, %a
+ %cmp = icmp eq i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne
+; CHECK-NEXT: icmp ne i8 %a, 2
+define i1 @exact_lshr_ne(i8 %a) {
+ %shr = lshr exact i8 4, %a
+ %cmp = icmp ne i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq
+; CHECK-NEXT: icmp eq i8 %a, 7
+define i1 @nonexact_ashr_eq(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp eq i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne
+; CHECK-NEXT: icmp ne i8 %a, 7
+define i1 @nonexact_ashr_ne(i8 %a) {
+ %shr = ashr i8 -128, %a
+ %cmp = icmp ne i8 %shr, -1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq
+; CHECK-NEXT: icmp eq i8 %a, 2
+define i1 @nonexact_lshr_eq(i8 %a) {
+ %shr = lshr i8 4, %a
+ %cmp = icmp eq i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne
+; CHECK-NEXT: icmp ne i8 %a, 2
+define i1 @nonexact_lshr_ne(i8 %a) {
+ %shr = lshr i8 4, %a
+ %cmp = icmp ne i8 %shr, 1
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_exactdiv
+; CHECK-NEXT: icmp eq i8 %a, 4
+define i1 @exact_lshr_eq_exactdiv(i8 %a) {
+ %shr = lshr exact i8 80, %a
+ %cmp = icmp eq i8 %shr, 5
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_exactdiv
+; CHECK-NEXT: icmp ne i8 %a, 4
+define i1 @exact_lshr_ne_exactdiv(i8 %a) {
+ %shr = lshr exact i8 80, %a
+ %cmp = icmp ne i8 %shr, 5
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq_exactdiv
+; CHECK-NEXT: icmp eq i8 %a, 4
+define i1 @nonexact_lshr_eq_exactdiv(i8 %a) {
+ %shr = lshr i8 80, %a
+ %cmp = icmp eq i8 %shr, 5
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne_exactdiv
+; CHECK-NEXT: icmp ne i8 %a, 4
+define i1 @nonexact_lshr_ne_exactdiv(i8 %a) {
+ %shr = lshr i8 80, %a
+ %cmp = icmp ne i8 %shr, 5
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_exactdiv
+; CHECK-NEXT: icmp eq i8 %a, 4
+define i1 @exact_ashr_eq_exactdiv(i8 %a) {
+ %shr = ashr exact i8 -80, %a
+ %cmp = icmp eq i8 %shr, -5
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_exactdiv
+; CHECK-NEXT: icmp ne i8 %a, 4
+define i1 @exact_ashr_ne_exactdiv(i8 %a) {
+ %shr = ashr exact i8 -80, %a
+ %cmp = icmp ne i8 %shr, -5
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq_exactdiv
+; CHECK-NEXT: icmp eq i8 %a, 4
+define i1 @nonexact_ashr_eq_exactdiv(i8 %a) {
+ %shr = ashr i8 -80, %a
+ %cmp = icmp eq i8 %shr, -5
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne_exactdiv
+; CHECK-NEXT: icmp ne i8 %a, 4
+define i1 @nonexact_ashr_ne_exactdiv(i8 %a) {
+ %shr = ashr i8 -80, %a
+ %cmp = icmp ne i8 %shr, -5
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_noexactdiv
+; CHECK-NEXT: ret i1 false
+define i1 @exact_lshr_eq_noexactdiv(i8 %a) {
+ %shr = lshr exact i8 80, %a
+ %cmp = icmp eq i8 %shr, 31
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_noexactdiv
+; CHECK-NEXT: ret i1 true
+define i1 @exact_lshr_ne_noexactdiv(i8 %a) {
+ %shr = lshr exact i8 80, %a
+ %cmp = icmp ne i8 %shr, 31
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq_noexactdiv
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_lshr_eq_noexactdiv(i8 %a) {
+ %shr = lshr i8 80, %a
+ %cmp = icmp eq i8 %shr, 31
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne_noexactdiv
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_lshr_ne_noexactdiv(i8 %a) {
+ %shr = lshr i8 80, %a
+ %cmp = icmp ne i8 %shr, 31
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_noexactdiv
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_eq_noexactdiv(i8 %a) {
+ %shr = ashr exact i8 -80, %a
+ %cmp = icmp eq i8 %shr, -31
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_noexactdiv
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_ne_noexactdiv(i8 %a) {
+ %shr = ashr exact i8 -80, %a
+ %cmp = icmp ne i8 %shr, -31
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq_noexactdiv
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_ashr_eq_noexactdiv(i8 %a) {
+ %shr = ashr i8 -80, %a
+ %cmp = icmp eq i8 %shr, -31
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne_noexactdiv
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_ashr_ne_noexactdiv(i8 %a) {
+ %shr = ashr i8 -80, %a
+ %cmp = icmp ne i8 %shr, -31
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_eq_noexactlog
+; CHECK-NEXT: ret i1 false
+define i1 @exact_lshr_eq_noexactlog(i8 %a) {
+ %shr = lshr exact i8 90, %a
+ %cmp = icmp eq i8 %shr, 30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_lshr_ne_noexactlog
+; CHECK-NEXT: ret i1 true
+define i1 @exact_lshr_ne_noexactlog(i8 %a) {
+ %shr = lshr exact i8 90, %a
+ %cmp = icmp ne i8 %shr, 30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_eq_noexactlog
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_lshr_eq_noexactlog(i8 %a) {
+ %shr = lshr i8 90, %a
+ %cmp = icmp eq i8 %shr, 30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_lshr_ne_noexactlog
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_lshr_ne_noexactlog(i8 %a) {
+ %shr = lshr i8 90, %a
+ %cmp = icmp ne i8 %shr, 30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_eq_noexactlog
+; CHECK-NEXT: ret i1 false
+define i1 @exact_ashr_eq_noexactlog(i8 %a) {
+ %shr = ashr exact i8 -90, %a
+ %cmp = icmp eq i8 %shr, -30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @exact_ashr_ne_noexactlog
+; CHECK-NEXT: ret i1 true
+define i1 @exact_ashr_ne_noexactlog(i8 %a) {
+ %shr = ashr exact i8 -90, %a
+ %cmp = icmp ne i8 %shr, -30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_eq_noexactlog
+; CHECK-NEXT: ret i1 false
+define i1 @nonexact_ashr_eq_noexactlog(i8 %a) {
+ %shr = ashr i8 -90, %a
+ %cmp = icmp eq i8 %shr, -30
+ ret i1 %cmp
+}
+
+; CHECK-LABEL: @nonexact_ashr_ne_noexactlog
+; CHECK-NEXT: ret i1 true
+define i1 @nonexact_ashr_ne_noexactlog(i8 %a) {
+ %shr = ashr i8 -90, %a
+ %cmp = icmp ne i8 %shr, -30
+ ret i1 %cmp
+}