[NFC][InstCombine] Revisit canonicalize-constant-low-bit-mask-and-icmp-s* tests in preparatio for PR42198.

The `icmp sgt`/`icmp sle` variants are, too, miscompiles:
https://rise4fun.com/Alive/JFNP
https://rise4fun.com/Alive/jHvL
A precondition 'x != 0' was forgotten by me.

While ensuring test coverage for `-1`, also add test coverage
for `0` mask. Mask `0` is allowed for all the folds,
mask `-1` is allowed for all the folds with unsigned `icmp` pred.
Constant mask `0` is missed though.

https://bugs.llvm.org/show_bug.cgi?id=42198

llvm-svn: 362910

10 files changed, 451 insertions, 227 deletions

diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-eq-to-icmp-ule.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-eq-to-icmp-ule.ll
index f46bcdfc997..bb304d7fa96 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-eq-to-icmp-ule.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-eq-to-icmp-ule.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x u<= C
 ; Iff: isPowerOf2(C + 1)
+; C can be 0 and -1.
 
 ; ============================================================================ ;
 ; Basic positive tests
@@ -59,6 +60,26 @@ define <2 x i1> @p2_vec_nonsplat(<2 x i8> %x) {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase0(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase0(
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X:%.*]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp eq <2 x i8> [[TMP0]], [[X]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp eq <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+define <2 x i1> @p2_vec_nonsplat_edgecase1(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase1(
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ule <2 x i8> [[X:%.*]], <i8 3, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[TMP1]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 -1>
+  %ret = icmp eq <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef(<3 x i8> %x) {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult <3 x i8> [[X:%.*]], <i8 4, i8 undef, i8 4>
diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ne-to-icmp-ugt.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ne-to-icmp-ugt.ll
index 850266381e7..35ae2600c9a 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ne-to-icmp-ugt.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ne-to-icmp-ugt.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x u> C
 ; Iff: isPowerOf2(C + 1)
+; C can be 0 and -1.
 
 ; ============================================================================ ;
 ; Basic positive tests
@@ -59,6 +60,26 @@ define <2 x i1> @p2_vec_nonsplat(<2 x i8> %x) {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase0(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase0(
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X:%.*]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp ne <2 x i8> [[TMP0]], [[X]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp ne <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+define <2 x i1> @p2_vec_nonsplat_edgecase1(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase1(
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt <2 x i8> [[X:%.*]], <i8 3, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[TMP1]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 -1>
+  %ret = icmp ne <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef(<3 x i8> %x) {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt <3 x i8> [[X:%.*]], <i8 3, i8 undef, i8 3>
diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sge-to-icmp-sle.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sge-to-icmp-sle.ll
index ca1b86c0623..3ed42e415c2 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sge-to-icmp-sle.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sge-to-icmp-sle.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x s<= C
 ; Iff: isPowerOf2(C + 1)
+; C must not be -1, but may be 0.
 
 ; ============================================================================ ;
 ; Basic positive tests
@@ -47,6 +48,17 @@ define <2 x i1> @p2_vec_nonsplat(<2 x i8> %x) {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase(
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X:%.*]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp sge <2 x i8> [[TMP0]], [[X]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp sge <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef(<3 x i8> %x) {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt <3 x i8> [[X:%.*]], <i8 4, i8 undef, i8 4>
@@ -80,9 +92,7 @@ define i1 @oneuse0(i8 %x) {
 ; Negative tests
 ; ============================================================================ ;
 
-; ============================================================================ ;
 ; Commutativity tests.
-; ============================================================================ ;
 
 declare i8 @gen8()
 
@@ -100,57 +110,7 @@ define i1 @c0() {
 }
 
 ; ============================================================================ ;
-; Commutativity tests with variable
-; ============================================================================ ;
-
-; Ok, this one should fold. We only testing commutativity of 'and'.
-define i1 @cv0(i8 %y) {
-; CHECK-LABEL: @cv0(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]
-; CHECK-NEXT:    [[RET:%.*]] = icmp sge i8 [[TMP1]], [[X]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = lshr i8 -1, %y
-  %tmp1 = and i8 %x, %tmp0 ; swapped order
-  %ret = icmp sge i8 %tmp1, %x
-  ret i1 %ret
-}
-
-define i1 @cv1(i8 %y) {
-; CHECK-LABEL: @cv1(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[TMP0]], [[X]]
-; CHECK-NEXT:    [[RET:%.*]] = icmp sge i8 [[X]], [[TMP1]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = lshr i8 -1, %y
-  %tmp1 = and i8 %tmp0, %x
-  %ret = icmp sge i8 %x, %tmp1 ; swapped order
-  ret i1 %ret
-}
-
-define i1 @cv2(i8 %y) {
-; CHECK-LABEL: @cv2(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]
-; CHECK-NEXT:    [[RET:%.*]] = icmp sge i8 [[X]], [[TMP1]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = lshr i8 -1, %y
-  %tmp1 = and i8 %x, %tmp0 ; swapped order
-  %ret = icmp sge i8 %x, %tmp1 ; swapped order
-  ret i1 %ret
-}
-
-; ============================================================================ ;
-; Normal negative tests
+; Rest of negative tests
 ; ============================================================================ ;
 
 define i1 @n0(i8 %x) {
@@ -224,3 +184,50 @@ define <3 x i1> @n4_vec(<3 x i8> %x) {
   %ret = icmp sge <3 x i8> %tmp0, %x
   ret <3 x i1> %ret
 }
+
+; Commutativity tests with variable
+
+define i1 @cv0(i8 %y) {
+; CHECK-LABEL: @cv0(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]
+; CHECK-NEXT:    [[RET:%.*]] = icmp sge i8 [[TMP1]], [[X]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = lshr i8 -1, %y
+  %tmp1 = and i8 %x, %tmp0 ; swapped order
+  %ret = icmp sge i8 %tmp1, %x
+  ret i1 %ret
+}
+
+define i1 @cv1(i8 %y) {
+; CHECK-LABEL: @cv1(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[TMP0]], [[X]]
+; CHECK-NEXT:    [[RET:%.*]] = icmp sge i8 [[X]], [[TMP1]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = lshr i8 -1, %y
+  %tmp1 = and i8 %tmp0, %x
+  %ret = icmp sge i8 %x, %tmp1 ; swapped order
+  ret i1 %ret
+}
+
+define i1 @cv2(i8 %y) {
+; CHECK-LABEL: @cv2(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]
+; CHECK-NEXT:    [[RET:%.*]] = icmp sge i8 [[X]], [[TMP1]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = lshr i8 -1, %y
+  %tmp1 = and i8 %x, %tmp0 ; swapped order
+  %ret = icmp sge i8 %x, %tmp1 ; swapped order
+  ret i1 %ret
+}
diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sgt-to-icmp-sgt.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sgt-to-icmp-sgt.ll
index 299ee78b7db..d58b93bf5ad 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sgt-to-icmp-sgt.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sgt-to-icmp-sgt.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x s> C
 ; Iff: isPowerOf2(C + 1)
+; C must not be -1, but may be 0.
 
 ; NOTE: this pattern is not commutative!
 
@@ -31,20 +32,6 @@ define i1 @p0() {
   ret i1 %ret
 }
 
-define i1 @pv(i8 %y) {
-; CHECK-LABEL: @pv(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt i8 [[X]], [[TMP0]]
-; CHECK-NEXT:    ret i1 [[TMP1]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = lshr i8 -1, %y
-  %tmp1 = and i8 %tmp0, %x
-  %ret = icmp sgt i8 %x, %tmp1
-  ret i1 %ret
-}
-
 ; ============================================================================ ;
 ; Vector tests
 ; ============================================================================ ;
@@ -73,6 +60,19 @@ define <2 x i1> @p2_vec_nonsplat() {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase() {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp sgt <2 x i8> [[X]], [[TMP0]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp sgt <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef() {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[X:%.*]] = call <3 x i8> @gen3x8()
@@ -110,9 +110,7 @@ define i1 @oneuse0() {
 ; Negative tests
 ; ============================================================================ ;
 
-; ============================================================================ ;
 ; Commutativity tests.
-; ============================================================================ ;
 
 define i1 @c0(i8 %x) {
 ; CHECK-LABEL: @c0(
@@ -126,9 +124,92 @@ define i1 @c0(i8 %x) {
 }
 
 ; ============================================================================ ;
-; Commutativity tests with variable
+; Rest of negative tests
 ; ============================================================================ ;
 
+define i1 @n0() {
+; CHECK-LABEL: @n0(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and i8 [[X]], 4
+; CHECK-NEXT:    [[RET:%.*]] = icmp sgt i8 [[X]], [[TMP0]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = and i8 %x, 4 ; power-of-two, but invalid.
+  %ret = icmp sgt i8 %x, %tmp0
+  ret i1 %ret
+}
+
+define i1 @n1(i8 %y, i8 %notx) {
+; CHECK-LABEL: @n1(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and i8 [[X]], 3
+; CHECK-NEXT:    [[RET:%.*]] = icmp sgt i8 [[TMP0]], [[NOTX:%.*]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = and i8 %x, 3
+  %ret = icmp sgt i8 %tmp0, %notx ; not %x
+  ret i1 %ret
+}
+
+define <2 x i1> @n2() {
+; CHECK-LABEL: @n2(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 16>
+; CHECK-NEXT:    [[RET:%.*]] = icmp sgt <2 x i8> [[X]], [[TMP0]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 16> ; only the first one is valid.
+  %ret = icmp sgt <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+
+; ============================================================================ ;
+; Potential miscompiles.
+; ============================================================================ ;
+
+define i1 @pv(i8 %y) {
+; CHECK-LABEL: @pv(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt i8 [[X]], [[TMP0]]
+; CHECK-NEXT:    ret i1 [[TMP1]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = lshr i8 -1, %y
+  %tmp1 = and i8 %tmp0, %x
+  %ret = icmp sgt i8 %x, %tmp1
+  ret i1 %ret
+}
+
+define <2 x i1> @n3_vec() {
+; CHECK-LABEL: @n3_vec(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt <2 x i8> [[X]], <i8 3, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[TMP1]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 -1>
+  %ret = icmp sgt <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+
+define <3 x i1> @n4_vec() {
+; CHECK-LABEL: @n4_vec(
+; CHECK-NEXT:    [[X:%.*]] = call <3 x i8> @gen3x8()
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt <3 x i8> [[X]], <i8 3, i8 undef, i8 -1>
+; CHECK-NEXT:    ret <3 x i1> [[TMP1]]
+;
+  %x = call <3 x i8> @gen3x8()
+  %tmp0 = and <3 x i8> %x, <i8 3, i8 undef, i8 -1>
+  %ret = icmp sgt <3 x i8> %x, %tmp0
+  ret <3 x i1> %ret
+}
+
+; Commutativity tests with variable
+
 ; Ok, this one should fold. We only testing commutativity of 'and'.
 define i1 @cv0_GOOD(i8 %y) {
 ; CHECK-LABEL: @cv0_GOOD(
@@ -171,46 +252,3 @@ define i1 @cv2(i8 %x, i8 %y) {
   %ret = icmp sgt i8 %tmp1, %x ; swapped order
   ret i1 %ret
 }
-
-; ============================================================================ ;
-; Normal negative tests
-; ============================================================================ ;
-
-define i1 @n0() {
-; CHECK-LABEL: @n0(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = and i8 [[X]], 4
-; CHECK-NEXT:    [[RET:%.*]] = icmp sgt i8 [[X]], [[TMP0]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = and i8 %x, 4 ; power-of-two, but invalid.
-  %ret = icmp sgt i8 %x, %tmp0
-  ret i1 %ret
-}
-
-define i1 @n1(i8 %y, i8 %notx) {
-; CHECK-LABEL: @n1(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = and i8 [[X]], 3
-; CHECK-NEXT:    [[RET:%.*]] = icmp sgt i8 [[TMP0]], [[NOTX:%.*]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = and i8 %x, 3
-  %ret = icmp sgt i8 %tmp0, %notx ; not %x
-  ret i1 %ret
-}
-
-define <2 x i1> @n2() {
-; CHECK-LABEL: @n2(
-; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
-; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 16>
-; CHECK-NEXT:    [[RET:%.*]] = icmp sgt <2 x i8> [[X]], [[TMP0]]
-; CHECK-NEXT:    ret <2 x i1> [[RET]]
-;
-  %x = call <2 x i8> @gen2x8()
-  %tmp0 = and <2 x i8> %x, <i8 3, i8 16> ; only the first one is valid.
-  %ret = icmp sgt <2 x i8> %x, %tmp0
-  ret <2 x i1> %ret
-}
diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sle-to-icmp-sle.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sle-to-icmp-sle.ll
index 11596fc7540..47e10102c58 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sle-to-icmp-sle.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-sle-to-icmp-sle.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x s<= C
 ; Iff: isPowerOf2(C + 1)
+; C must not be -1, but may be 0.
 
 ; NOTE: this pattern is not commutative!
 
@@ -31,20 +32,6 @@ define i1 @p0() {
   ret i1 %ret
 }
 
-define i1 @pv(i8 %y) {
-; CHECK-LABEL: @pv(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp sle i8 [[X]], [[TMP0]]
-; CHECK-NEXT:    ret i1 [[TMP1]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = lshr i8 -1, %y
-  %tmp1 = and i8 %tmp0, %x
-  %ret = icmp sle i8 %x, %tmp1
-  ret i1 %ret
-}
-
 ; ============================================================================ ;
 ; Vector tests
 ; ============================================================================ ;
@@ -73,6 +60,19 @@ define <2 x i1> @p2_vec_nonsplat() {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase() {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp sle <2 x i8> [[X]], [[TMP0]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp sle <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef() {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[X:%.*]] = call <3 x i8> @gen3x8()
@@ -110,9 +110,7 @@ define i1 @oneuse0() {
 ; Negative tests
 ; ============================================================================ ;
 
-; ============================================================================ ;
 ; Commutativity tests.
-; ============================================================================ ;
 
 define i1 @c0(i8 %x) {
 ; CHECK-LABEL: @c0(
@@ -126,10 +124,92 @@ define i1 @c0(i8 %x) {
 }
 
 ; ============================================================================ ;
-; Commutativity tests with variable
+; Rest of negative tests
 ; ============================================================================ ;
 
-; Ok, this one should fold. We only testing commutativity of 'and'.
+define i1 @n0() {
+; CHECK-LABEL: @n0(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and i8 [[X]], 4
+; CHECK-NEXT:    [[RET:%.*]] = icmp sle i8 [[X]], [[TMP0]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = and i8 %x, 4 ; power-of-two, but invalid.
+  %ret = icmp sle i8 %x, %tmp0
+  ret i1 %ret
+}
+
+define i1 @n1(i8 %y, i8 %notx) {
+; CHECK-LABEL: @n1(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and i8 [[X]], 3
+; CHECK-NEXT:    [[RET:%.*]] = icmp sle i8 [[TMP0]], [[NOTX:%.*]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = and i8 %x, 3
+  %ret = icmp sle i8 %tmp0, %notx ; not %x
+  ret i1 %ret
+}
+
+define <2 x i1> @n2() {
+; CHECK-LABEL: @n2(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 16>
+; CHECK-NEXT:    [[RET:%.*]] = icmp sle <2 x i8> [[X]], [[TMP0]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 16> ; only the first one is valid.
+  %ret = icmp sle <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+
+; ============================================================================ ;
+; Potential miscompiles.
+; ============================================================================ ;
+
+define i1 @pv(i8 %y) {
+; CHECK-LABEL: @pv(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp sle i8 [[X]], [[TMP0]]
+; CHECK-NEXT:    ret i1 [[TMP1]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = lshr i8 -1, %y
+  %tmp1 = and i8 %tmp0, %x
+  %ret = icmp sle i8 %x, %tmp1
+  ret i1 %ret
+}
+
+define <2 x i1> @n3_vec() {
+; CHECK-LABEL: @n3_vec(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt <2 x i8> [[X]], <i8 4, i8 0>
+; CHECK-NEXT:    ret <2 x i1> [[TMP1]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 -1>
+  %ret = icmp sle <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+
+define <3 x i1> @n4_vec() {
+; CHECK-LABEL: @n4_vec(
+; CHECK-NEXT:    [[X:%.*]] = call <3 x i8> @gen3x8()
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp slt <3 x i8> [[X]], <i8 4, i8 undef, i8 0>
+; CHECK-NEXT:    ret <3 x i1> [[TMP1]]
+;
+  %x = call <3 x i8> @gen3x8()
+  %tmp0 = and <3 x i8> %x, <i8 3, i8 undef, i8 -1>
+  %ret = icmp sle <3 x i8> %x, %tmp0
+  ret <3 x i1> %ret
+}
+
+; Commutativity tests with variable
+
 define i1 @cv0_GOOD(i8 %y) {
 ; CHECK-LABEL: @cv0_GOOD(
 ; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
@@ -171,46 +251,3 @@ define i1 @cv2(i8 %x, i8 %y) {
   %ret = icmp sle i8 %tmp1, %x ; swapped order
   ret i1 %ret
 }
-
-; ============================================================================ ;
-; Normal negative tests
-; ============================================================================ ;
-
-define i1 @n0() {
-; CHECK-LABEL: @n0(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = and i8 [[X]], 4
-; CHECK-NEXT:    [[RET:%.*]] = icmp sle i8 [[X]], [[TMP0]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = and i8 %x, 4 ; power-of-two, but invalid.
-  %ret = icmp sle i8 %x, %tmp0
-  ret i1 %ret
-}
-
-define i1 @n1(i8 %y, i8 %notx) {
-; CHECK-LABEL: @n1(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = and i8 [[X]], 3
-; CHECK-NEXT:    [[RET:%.*]] = icmp sle i8 [[TMP0]], [[NOTX:%.*]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = and i8 %x, 3
-  %ret = icmp sle i8 %tmp0, %notx ; not %x
-  ret i1 %ret
-}
-
-define <2 x i1> @n2() {
-; CHECK-LABEL: @n2(
-; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
-; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 16>
-; CHECK-NEXT:    [[RET:%.*]] = icmp sle <2 x i8> [[X]], [[TMP0]]
-; CHECK-NEXT:    ret <2 x i1> [[RET]]
-;
-  %x = call <2 x i8> @gen2x8()
-  %tmp0 = and <2 x i8> %x, <i8 3, i8 16> ; only the first one is valid.
-  %ret = icmp sle <2 x i8> %x, %tmp0
-  ret <2 x i1> %ret
-}
diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-slt-to-icmp-sgt.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-slt-to-icmp-sgt.ll
index 2957ad5731c..7cda5727272 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-slt-to-icmp-sgt.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-slt-to-icmp-sgt.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x s> C
 ; Iff: isPowerOf2(C + 1)
+; C must not be -1, but may be 0.
 
 ; ============================================================================ ;
 ; Basic positive tests
@@ -47,6 +48,17 @@ define <2 x i1> @p2_vec_nonsplat(<2 x i8> %x) {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase(
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X:%.*]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp slt <2 x i8> [[TMP0]], [[X]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp slt <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef(<3 x i8> %x) {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt <3 x i8> [[X:%.*]], <i8 3, i8 undef, i8 3>
@@ -80,9 +92,7 @@ define i1 @oneuse0(i8 %x) {
 ; Negative tests
 ; ============================================================================ ;
 
-; ============================================================================ ;
 ; Commutativity tests.
-; ============================================================================ ;
 
 declare i8 @gen8()
 
@@ -100,57 +110,7 @@ define i1 @c0() {
 }
 
 ; ============================================================================ ;
-; Commutativity tests with variable
-; ============================================================================ ;
-
-; Ok, this one should fold. We only testing commutativity of 'and'.
-define i1 @cv0(i8 %y) {
-; CHECK-LABEL: @cv0(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]
-; CHECK-NEXT:    [[RET:%.*]] = icmp slt i8 [[TMP1]], [[X]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = lshr i8 -1, %y
-  %tmp1 = and i8 %x, %tmp0 ; swapped order
-  %ret = icmp slt i8 %tmp1, %x
-  ret i1 %ret
-}
-
-define i1 @cv1(i8 %y) {
-; CHECK-LABEL: @cv1(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[TMP0]], [[X]]
-; CHECK-NEXT:    [[RET:%.*]] = icmp slt i8 [[X]], [[TMP1]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = lshr i8 -1, %y
-  %tmp1 = and i8 %tmp0, %x
-  %ret = icmp slt i8 %x, %tmp1 ; swapped order
-  ret i1 %ret
-}
-
-define i1 @cv2(i8 %y) {
-; CHECK-LABEL: @cv2(
-; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
-; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
-; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]
-; CHECK-NEXT:    [[RET:%.*]] = icmp slt i8 [[X]], [[TMP1]]
-; CHECK-NEXT:    ret i1 [[RET]]
-;
-  %x = call i8 @gen8()
-  %tmp0 = lshr i8 -1, %y
-  %tmp1 = and i8 %x, %tmp0 ; swapped order
-  %ret = icmp slt i8 %x, %tmp1 ; swapped order
-  ret i1 %ret
-}
-
-; ============================================================================ ;
-; Normal negative tests
+; Rest of negative tests
 ; ============================================================================ ;
 
 define i1 @n0(i8 %x) {
@@ -224,3 +184,50 @@ define <3 x i1> @n4(<3 x i8> %x) {
   %ret = icmp slt <3 x i8> %tmp0, %x
   ret <3 x i1> %ret
 }
+
+; Commutativity tests with variable
+
+define i1 @cv0(i8 %y) {
+; CHECK-LABEL: @cv0(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]
+; CHECK-NEXT:    [[RET:%.*]] = icmp slt i8 [[TMP1]], [[X]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = lshr i8 -1, %y
+  %tmp1 = and i8 %x, %tmp0 ; swapped order
+  %ret = icmp slt i8 %tmp1, %x
+  ret i1 %ret
+}
+
+define i1 @cv1(i8 %y) {
+; CHECK-LABEL: @cv1(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[TMP0]], [[X]]
+; CHECK-NEXT:    [[RET:%.*]] = icmp slt i8 [[X]], [[TMP1]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = lshr i8 -1, %y
+  %tmp1 = and i8 %tmp0, %x
+  %ret = icmp slt i8 %x, %tmp1 ; swapped order
+  ret i1 %ret
+}
+
+define i1 @cv2(i8 %y) {
+; CHECK-LABEL: @cv2(
+; CHECK-NEXT:    [[X:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[TMP0:%.*]] = lshr i8 -1, [[Y:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], [[TMP0]]
+; CHECK-NEXT:    [[RET:%.*]] = icmp slt i8 [[X]], [[TMP1]]
+; CHECK-NEXT:    ret i1 [[RET]]
+;
+  %x = call i8 @gen8()
+  %tmp0 = lshr i8 -1, %y
+  %tmp1 = and i8 %x, %tmp0 ; swapped order
+  %ret = icmp slt i8 %x, %tmp1 ; swapped order
+  ret i1 %ret
+}
diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-uge-to-icmp-ule.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-uge-to-icmp-ule.ll
index f17d6b47a08..18325ed1759 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-uge-to-icmp-ule.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-uge-to-icmp-ule.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x u<= C
 ; Iff: isPowerOf2(C + 1)
+; C can be 0 and -1.
 
 ; ============================================================================ ;
 ; Basic positive tests
@@ -59,6 +60,26 @@ define <2 x i1> @p2_vec_nonsplat(<2 x i8> %x) {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase0(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase0(
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X:%.*]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp uge <2 x i8> [[TMP0]], [[X]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp uge <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+define <2 x i1> @p2_vec_nonsplat_edgecase1(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase1(
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ule <2 x i8> [[X:%.*]], <i8 3, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[TMP1]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 -1>
+  %ret = icmp uge <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef(<3 x i8> %x) {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult <3 x i8> [[X:%.*]], <i8 4, i8 undef, i8 4>
diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ugt-to-icmp-ugt.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ugt-to-icmp-ugt.ll
index 7512b72f2a7..38a57d6d267 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ugt-to-icmp-ugt.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ugt-to-icmp-ugt.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x u> C
 ; Iff: isPowerOf2(C + 1)
+; C can be 0 and -1.
 
 declare i8 @gen8()
 declare <2 x i8> @gen2x8()
@@ -71,6 +72,30 @@ define <2 x i1> @p2_vec_nonsplat() {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase0() {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase0(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp ugt <2 x i8> [[X]], [[TMP0]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp ugt <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+define <2 x i1> @p2_vec_nonsplat_edgecase1() {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase1(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt <2 x i8> [[X]], <i8 3, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[TMP1]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 -1>
+  %ret = icmp ugt <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef() {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[X:%.*]] = call <3 x i8> @gen3x8()
diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ule-to-icmp-ule.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ule-to-icmp-ule.ll
index 0bab709618d..6f267206dbe 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ule-to-icmp-ule.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ule-to-icmp-ule.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x u<= C
 ; Iff: isPowerOf2(C + 1)
+; C can be 0 and -1.
 
 declare i8 @gen8()
 declare <2 x i8> @gen2x8()
@@ -71,6 +72,30 @@ define <2 x i1> @p2_vec_nonsplat() {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase0() {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase0(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp ule <2 x i8> [[X]], [[TMP0]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp ule <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+define <2 x i1> @p2_vec_nonsplat_edgecase1() {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase1(
+; CHECK-NEXT:    [[X:%.*]] = call <2 x i8> @gen2x8()
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ule <2 x i8> [[X]], <i8 3, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[TMP1]]
+;
+  %x = call <2 x i8> @gen2x8()
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 -1>
+  %ret = icmp ule <2 x i8> %x, %tmp0
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef() {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[X:%.*]] = call <3 x i8> @gen3x8()
diff --git a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll
index 287e3699932..ad0f0cf3c0e 100644
--- a/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll
+++ b/llvm/test/Transforms/InstCombine/canonicalize-constant-low-bit-mask-and-icmp-ult-to-icmp-ugt.ll
@@ -8,6 +8,7 @@
 ; Should be transformed into:
 ;   x u> C
 ; Iff: isPowerOf2(C + 1)
+; C can be 0 and -1.
 
 ; ============================================================================ ;
 ; Basic positive tests
@@ -59,6 +60,27 @@ define <2 x i1> @p2_vec_nonsplat(<2 x i8> %x) {
   ret <2 x i1> %ret
 }
 
+define <2 x i1> @p2_vec_nonsplat_edgecase0(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase0(
+; CHECK-NEXT:    [[TMP0:%.*]] = and <2 x i8> [[X:%.*]], <i8 3, i8 0>
+; CHECK-NEXT:    [[RET:%.*]] = icmp ult <2 x i8> [[TMP0]], [[X]]
+; CHECK-NEXT:    ret <2 x i1> [[RET]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 0>
+  %ret = icmp ult <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+
+define <2 x i1> @p2_vec_nonsplat_edgecase1(<2 x i8> %x) {
+; CHECK-LABEL: @p2_vec_nonsplat_edgecase1(
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt <2 x i8> [[X:%.*]], <i8 3, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[TMP1]]
+;
+  %tmp0 = and <2 x i8> %x, <i8 3, i8 -1>
+  %ret = icmp ult <2 x i8> %tmp0, %x
+  ret <2 x i1> %ret
+}
+
 define <3 x i1> @p3_vec_splat_undef(<3 x i8> %x) {
 ; CHECK-LABEL: @p3_vec_splat_undef(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp ugt <3 x i8> [[X:%.*]], <i8 3, i8 undef, i8 3>