[llvm] r342074 - [NFC][InstCombine] R38708 - inefficient pattern for high-bits checking.
Roman Lebedev via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 12 12:44:27 PDT 2018
Author: lebedevri
Date: Wed Sep 12 12:44:26 2018
New Revision: 342074
URL: http://llvm.org/viewvc/llvm-project?rev=342074&view=rev
Log:
[NFC][InstCombine] R38708 - inefficient pattern for high-bits checking.
More complicated, canonical pattern:
https://rise4fun.com/Alive/uhA
https://godbolt.org/z/o4RB8D
Also, we need to be careful not to skip some patters...
https://bugs.llvm.org/show_bug.cgi?id=38708
Added:
llvm/trunk/test/Transforms/InstCombine/icmp-uge-of-not-of-shl-allones-by-bits-and-val-to-icmp-eq-of-lshr-val-by-bits-and-0.ll
llvm/trunk/test/Transforms/InstCombine/icmp-ult-of-not-of-shl-allones-by-bits-and-val-to-icmp-ne-of-lshr-val-by-bits-and-0.ll
llvm/trunk/test/Transforms/InstCombine/interference-tests-for-high-bit-check.ll
Added: llvm/trunk/test/Transforms/InstCombine/icmp-uge-of-not-of-shl-allones-by-bits-and-val-to-icmp-eq-of-lshr-val-by-bits-and-0.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp-uge-of-not-of-shl-allones-by-bits-and-val-to-icmp-eq-of-lshr-val-by-bits-and-0.ll?rev=342074&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp-uge-of-not-of-shl-allones-by-bits-and-val-to-icmp-eq-of-lshr-val-by-bits-and-0.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/icmp-uge-of-not-of-shl-allones-by-bits-and-val-to-icmp-eq-of-lshr-val-by-bits-and-0.ll Wed Sep 12 12:44:26 2018
@@ -0,0 +1,240 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; https://bugs.llvm.org/show_bug.cgi?id=38708
+
+; Pattern:
+; ~(-1 << bits) u>= val
+; Should be transformed into:
+; (val l>> bits) == 0
+
+; ============================================================================ ;
+; Basic positive tests
+; ============================================================================ ;
+
+define i1 @p0(i8 %val, i8 %bits) {
+; CHECK-LABEL: @p0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ %r = icmp uge i8 %t1, %val
+ ret i1 %r
+}
+
+; ============================================================================ ;
+; Vector tests
+; ============================================================================ ;
+
+define <2 x i1> @p1_vec(<2 x i8> %val, <2 x i8> %bits) {
+; CHECK-LABEL: @p1_vec(
+; CHECK-NEXT: [[T0:%.*]] = shl <2 x i8> <i8 -1, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <2 x i8> [[T0]], <i8 -1, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp uge <2 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <2 x i1> [[R]]
+;
+ %t0 = shl <2 x i8> <i8 -1, i8 -1>, %bits
+ %t1 = xor <2 x i8> %t0, <i8 -1, i8 -1>
+ %r = icmp uge <2 x i8> %t1, %val
+ ret <2 x i1> %r
+}
+
+define <3 x i1> @p2_vec_undef0(<3 x i8> %val, <3 x i8> %bits) {
+; CHECK-LABEL: @p2_vec_undef0(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i8> <i8 -1, i8 undef, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <3 x i8> [[T0]], <i8 -1, i8 -1, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp uge <3 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <3 x i1> [[R]]
+;
+ %t0 = shl <3 x i8> <i8 -1, i8 undef, i8 -1>, %bits
+ %t1 = xor <3 x i8> %t0, <i8 -1, i8 -1, i8 -1>
+ %r = icmp uge <3 x i8> %t1, %val
+ ret <3 x i1> %r
+}
+
+define <3 x i1> @p2_vec_undef1(<3 x i8> %val, <3 x i8> %bits) {
+; CHECK-LABEL: @p2_vec_undef1(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i8> <i8 -1, i8 -1, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <3 x i8> [[T0]], <i8 -1, i8 undef, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp uge <3 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <3 x i1> [[R]]
+;
+ %t0 = shl <3 x i8> <i8 -1, i8 -1, i8 -1>, %bits
+ %t1 = xor <3 x i8> %t0, <i8 -1, i8 undef, i8 -1>
+ %r = icmp uge <3 x i8> %t1, %val
+ ret <3 x i1> %r
+}
+
+define <3 x i1> @p2_vec_undef2(<3 x i8> %val, <3 x i8> %bits) {
+; CHECK-LABEL: @p2_vec_undef2(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i8> <i8 -1, i8 undef, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <3 x i8> [[T0]], <i8 -1, i8 undef, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp uge <3 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <3 x i1> [[R]]
+;
+ %t0 = shl <3 x i8> <i8 -1, i8 undef, i8 -1>, %bits
+ %t1 = xor <3 x i8> %t0, <i8 -1, i8 undef, i8 -1>
+ %r = icmp uge <3 x i8> %t1, %val
+ ret <3 x i1> %r
+}
+
+; ============================================================================ ;
+; Commutativity tests.
+; ============================================================================ ;
+
+declare i8 @gen8()
+
+define i1 @c0(i8 %bits) {
+; CHECK-LABEL: @c0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[VAL:%.*]] = call i8 @gen8()
+; CHECK-NEXT: [[R:%.*]] = icmp ule i8 [[VAL]], [[T1]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ %val = call i8 @gen8()
+ %r = icmp ule i8 %val, %t1 ; swapped order and predicate
+ ret i1 %r
+}
+
+; ============================================================================ ;
+; One-use tests.
+; ============================================================================ ;
+
+declare void @use8(i8)
+
+define i1 @oneuse0(i8 %val, i8 %bits) {
+; CHECK-LABEL: @oneuse0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: call void @use8(i8 [[T0]])
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ call void @use8(i8 %t0)
+ %t1 = xor i8 %t0, -1
+ %r = icmp uge i8 %t1, %val
+ ret i1 %r
+}
+
+define i1 @oneuse1(i8 %val, i8 %bits) {
+; CHECK-LABEL: @oneuse1(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: call void @use8(i8 [[T1]])
+; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ call void @use8(i8 %t1)
+ %r = icmp uge i8 %t1, %val
+ ret i1 %r
+}
+
+define i1 @oneuse2(i8 %val, i8 %bits) {
+; CHECK-LABEL: @oneuse2(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: call void @use8(i8 [[T0]])
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: call void @use8(i8 [[T1]])
+; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ call void @use8(i8 %t0)
+ %t1 = xor i8 %t0, -1
+ call void @use8(i8 %t1)
+ %r = icmp uge i8 %t1, %val
+ ret i1 %r
+}
+
+; ============================================================================ ;
+; Negative tests
+; ============================================================================ ;
+
+define i1 @n0(i8 %val, i8 %bits) {
+; CHECK-LABEL: @n0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 1, %bits ; constant is not -1
+ %t1 = xor i8 %t0, -1
+ %r = icmp uge i8 %t1, %val
+ ret i1 %r
+}
+
+define i1 @n1(i8 %val, i8 %bits) {
+; CHECK-LABEL: @n1(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], 1
+; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, 1 ; not 'not'
+ %r = icmp uge i8 %t1, %val
+ ret i1 %r
+}
+
+define <2 x i1> @n2_vec_nonsplat(<2 x i8> %val, <2 x i8> %bits) {
+; CHECK-LABEL: @n2_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = shl <2 x i8> <i8 -1, i8 1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <2 x i8> [[T0]], <i8 -1, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp uge <2 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <2 x i1> [[R]]
+;
+ %t0 = shl <2 x i8> <i8 -1, i8 1>, %bits ; again, wrong constant
+ %t1 = xor <2 x i8> %t0, <i8 -1, i8 -1>
+ %r = icmp uge <2 x i8> %t1, %val
+ ret <2 x i1> %r
+}
+
+define <2 x i1> @n3_vec_nonsplat(<2 x i8> %val, <2 x i8> %bits) {
+; CHECK-LABEL: @n3_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = shl <2 x i8> <i8 -1, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <2 x i8> [[T0]], <i8 -1, i8 1>
+; CHECK-NEXT: [[R:%.*]] = icmp uge <2 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <2 x i1> [[R]]
+;
+ %t0 = shl <2 x i8> <i8 -1, i8 -1>, %bits
+ %t1 = xor <2 x i8> %t0, <i8 -1, i8 1> ; again, wrong constant
+ %r = icmp uge <2 x i8> %t1, %val
+ ret <2 x i1> %r
+}
+
+define i1 @n3(i8 %val, i8 %bits) {
+; CHECK-LABEL: @n3(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[R:%.*]] = icmp ugt i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ %r = icmp ugt i8 %t1, %val ; wrong predicate
+ ret i1 %r
+}
+
+define i1 @n4(i8 %bits) {
+; CHECK-LABEL: @n4(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[VAL:%.*]] = call i8 @gen8()
+; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[VAL]], [[T1]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ %val = call i8 @gen8()
+ %r = icmp ult i8 %val, %t1 ; swapped order and [wrong] predicate
+ ret i1 %r
+}
Added: llvm/trunk/test/Transforms/InstCombine/icmp-ult-of-not-of-shl-allones-by-bits-and-val-to-icmp-ne-of-lshr-val-by-bits-and-0.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp-ult-of-not-of-shl-allones-by-bits-and-val-to-icmp-ne-of-lshr-val-by-bits-and-0.ll?rev=342074&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp-ult-of-not-of-shl-allones-by-bits-and-val-to-icmp-ne-of-lshr-val-by-bits-and-0.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/icmp-ult-of-not-of-shl-allones-by-bits-and-val-to-icmp-ne-of-lshr-val-by-bits-and-0.ll Wed Sep 12 12:44:26 2018
@@ -0,0 +1,240 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; https://bugs.llvm.org/show_bug.cgi?id=38708
+
+; Pattern:
+; ~(-1 << bits) u< val
+; Should be transformed into:
+; (val l>> bits) != 0
+
+; ============================================================================ ;
+; Basic positive tests
+; ============================================================================ ;
+
+define i1 @p0(i8 %val, i8 %bits) {
+; CHECK-LABEL: @p0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ %r = icmp ult i8 %t1, %val
+ ret i1 %r
+}
+
+; ============================================================================ ;
+; Vector tests
+; ============================================================================ ;
+
+define <2 x i1> @p1_vec(<2 x i8> %val, <2 x i8> %bits) {
+; CHECK-LABEL: @p1_vec(
+; CHECK-NEXT: [[T0:%.*]] = shl <2 x i8> <i8 -1, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <2 x i8> [[T0]], <i8 -1, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp ult <2 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <2 x i1> [[R]]
+;
+ %t0 = shl <2 x i8> <i8 -1, i8 -1>, %bits
+ %t1 = xor <2 x i8> %t0, <i8 -1, i8 -1>
+ %r = icmp ult <2 x i8> %t1, %val
+ ret <2 x i1> %r
+}
+
+define <3 x i1> @p2_vec_undef0(<3 x i8> %val, <3 x i8> %bits) {
+; CHECK-LABEL: @p2_vec_undef0(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i8> <i8 -1, i8 undef, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <3 x i8> [[T0]], <i8 -1, i8 -1, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp ult <3 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <3 x i1> [[R]]
+;
+ %t0 = shl <3 x i8> <i8 -1, i8 undef, i8 -1>, %bits
+ %t1 = xor <3 x i8> %t0, <i8 -1, i8 -1, i8 -1>
+ %r = icmp ult <3 x i8> %t1, %val
+ ret <3 x i1> %r
+}
+
+define <3 x i1> @p2_vec_undef1(<3 x i8> %val, <3 x i8> %bits) {
+; CHECK-LABEL: @p2_vec_undef1(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i8> <i8 -1, i8 -1, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <3 x i8> [[T0]], <i8 -1, i8 undef, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp ult <3 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <3 x i1> [[R]]
+;
+ %t0 = shl <3 x i8> <i8 -1, i8 -1, i8 -1>, %bits
+ %t1 = xor <3 x i8> %t0, <i8 -1, i8 undef, i8 -1>
+ %r = icmp ult <3 x i8> %t1, %val
+ ret <3 x i1> %r
+}
+
+define <3 x i1> @p2_vec_undef2(<3 x i8> %val, <3 x i8> %bits) {
+; CHECK-LABEL: @p2_vec_undef2(
+; CHECK-NEXT: [[T0:%.*]] = shl <3 x i8> <i8 -1, i8 undef, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <3 x i8> [[T0]], <i8 -1, i8 undef, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp ult <3 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <3 x i1> [[R]]
+;
+ %t0 = shl <3 x i8> <i8 -1, i8 undef, i8 -1>, %bits
+ %t1 = xor <3 x i8> %t0, <i8 -1, i8 undef, i8 -1>
+ %r = icmp ult <3 x i8> %t1, %val
+ ret <3 x i1> %r
+}
+
+; ============================================================================ ;
+; Commutativity tests.
+; ============================================================================ ;
+
+declare i8 @gen8()
+
+define i1 @c0(i8 %bits) {
+; CHECK-LABEL: @c0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[VAL:%.*]] = call i8 @gen8()
+; CHECK-NEXT: [[R:%.*]] = icmp ugt i8 [[VAL]], [[T1]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ %val = call i8 @gen8()
+ %r = icmp ugt i8 %val, %t1 ; swapped order and predicate
+ ret i1 %r
+}
+
+; ============================================================================ ;
+; One-use tests.
+; ============================================================================ ;
+
+declare void @use8(i8)
+
+define i1 @oneuse0(i8 %val, i8 %bits) {
+; CHECK-LABEL: @oneuse0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: call void @use8(i8 [[T0]])
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ call void @use8(i8 %t0)
+ %t1 = xor i8 %t0, -1
+ %r = icmp ult i8 %t1, %val
+ ret i1 %r
+}
+
+define i1 @oneuse1(i8 %val, i8 %bits) {
+; CHECK-LABEL: @oneuse1(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: call void @use8(i8 [[T1]])
+; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ call void @use8(i8 %t1)
+ %r = icmp ult i8 %t1, %val
+ ret i1 %r
+}
+
+define i1 @oneuse2(i8 %val, i8 %bits) {
+; CHECK-LABEL: @oneuse2(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: call void @use8(i8 [[T0]])
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: call void @use8(i8 [[T1]])
+; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ call void @use8(i8 %t0)
+ %t1 = xor i8 %t0, -1
+ call void @use8(i8 %t1)
+ %r = icmp ult i8 %t1, %val
+ ret i1 %r
+}
+
+; ============================================================================ ;
+; Negative tests
+; ============================================================================ ;
+
+define i1 @n0(i8 %val, i8 %bits) {
+; CHECK-LABEL: @n0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 1, %bits ; constant is not -1
+ %t1 = xor i8 %t0, -1
+ %r = icmp ult i8 %t1, %val
+ ret i1 %r
+}
+
+define i1 @n1(i8 %val, i8 %bits) {
+; CHECK-LABEL: @n1(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], 1
+; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, 1 ; not 'not'
+ %r = icmp ult i8 %t1, %val
+ ret i1 %r
+}
+
+define <2 x i1> @n2_vec_nonsplat(<2 x i8> %val, <2 x i8> %bits) {
+; CHECK-LABEL: @n2_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = shl <2 x i8> <i8 -1, i8 1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <2 x i8> [[T0]], <i8 -1, i8 -1>
+; CHECK-NEXT: [[R:%.*]] = icmp ult <2 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <2 x i1> [[R]]
+;
+ %t0 = shl <2 x i8> <i8 -1, i8 1>, %bits ; again, wrong constant
+ %t1 = xor <2 x i8> %t0, <i8 -1, i8 -1>
+ %r = icmp ult <2 x i8> %t1, %val
+ ret <2 x i1> %r
+}
+
+define <2 x i1> @n3_vec_nonsplat(<2 x i8> %val, <2 x i8> %bits) {
+; CHECK-LABEL: @n3_vec_nonsplat(
+; CHECK-NEXT: [[T0:%.*]] = shl <2 x i8> <i8 -1, i8 -1>, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor <2 x i8> [[T0]], <i8 -1, i8 1>
+; CHECK-NEXT: [[R:%.*]] = icmp ult <2 x i8> [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret <2 x i1> [[R]]
+;
+ %t0 = shl <2 x i8> <i8 -1, i8 -1>, %bits
+ %t1 = xor <2 x i8> %t0, <i8 -1, i8 1> ; again, wrong constant
+ %r = icmp ult <2 x i8> %t1, %val
+ ret <2 x i1> %r
+}
+
+define i1 @n3(i8 %val, i8 %bits) {
+; CHECK-LABEL: @n3(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[R:%.*]] = icmp ule i8 [[T1]], [[VAL:%.*]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ %r = icmp ule i8 %t1, %val ; wrong predicate
+ ret i1 %r
+}
+
+define i1 @n4(i8 %bits) {
+; CHECK-LABEL: @n4(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[VAL:%.*]] = call i8 @gen8()
+; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[VAL]], [[T1]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits
+ %t1 = xor i8 %t0, -1
+ %val = call i8 @gen8()
+ %r = icmp uge i8 %val, %t1 ; swapped order and [wrong] predicate
+ ret i1 %r
+}
Added: llvm/trunk/test/Transforms/InstCombine/interference-tests-for-high-bit-check.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/interference-tests-for-high-bit-check.ll?rev=342074&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/interference-tests-for-high-bit-check.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/interference-tests-for-high-bit-check.ll Wed Sep 12 12:44:26 2018
@@ -0,0 +1,141 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; https://bugs.llvm.org/show_bug.cgi?id=38708
+
+; ============================================================================ ;
+; Interference tests.
+; We might accidentally skip some of these, if we are not careful.
+; ============================================================================ ;
+
+declare i8 @gen8()
+
+define i1 @interference0(i8 %bits0, i8 %bits1) {
+; CHECK-LABEL: @interference0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[T1_HIGHBITS:%.*]] = lshr i8 [[T1]], [[BITS1:%.*]]
+; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[T1_HIGHBITS]], 0
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits0
+ %t1 = xor i8 %t0, -1
+ %t2 = shl i8 1, %bits1
+ %r = icmp ult i8 %t1, %t2
+ ret i1 %r
+}
+
+define i1 @interference1(i8 %bits0, i8 %bits1) {
+; CHECK-LABEL: @interference1(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = shl i8 1, [[BITS1:%.*]]
+; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[T2]], [[T1]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits0
+ %t1 = xor i8 %t0, -1
+ %t2 = shl i8 1, %bits1
+ %r = icmp ule i8 %t1, %t2
+ ret i1 %r
+}
+
+define i1 @interference2(i8 %bits0, i8 %bits1) {
+; CHECK-LABEL: @interference2(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[T2:%.*]] = shl i8 1, [[BITS1:%.*]]
+; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[T2]], [[T1]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits0
+ %t1 = xor i8 %t0, -1
+ %t2 = shl i8 1, %bits1
+ %r = icmp ugt i8 %t1, %t2
+ ret i1 %r
+}
+
+define i1 @interference3(i8 %bits0, i8 %bits1) {
+; CHECK-LABEL: @interference3(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[T1_HIGHBITS:%.*]] = lshr i8 [[T1]], [[BITS1:%.*]]
+; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1_HIGHBITS]], 0
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits0
+ %t1 = xor i8 %t0, -1
+ %t2 = shl i8 1, %bits1
+ %r = icmp uge i8 %t1, %t2
+ ret i1 %r
+}
+
+
+
+define i1 @commuted_interference0(i8 %bits0) {
+; CHECK-LABEL: @commuted_interference0(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[BITS1:%.*]] = call i8 @gen8()
+; CHECK-NEXT: [[T1_HIGHBITS:%.*]] = lshr i8 [[T1]], [[BITS1]]
+; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[T1_HIGHBITS]], 0
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits0
+ %t1 = xor i8 %t0, -1
+ %bits1 = call i8 @gen8()
+ %t2 = shl i8 1, %bits1
+ %r = icmp ult i8 %t1, %t2
+ ret i1 %r
+}
+
+define i1 @commuted_interference1(i8 %bits0) {
+; CHECK-LABEL: @commuted_interference1(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[BITS1:%.*]] = call i8 @gen8()
+; CHECK-NEXT: [[T2:%.*]] = shl i8 1, [[BITS1]]
+; CHECK-NEXT: [[R:%.*]] = icmp uge i8 [[T2]], [[T1]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits0
+ %t1 = xor i8 %t0, -1
+ %bits1 = call i8 @gen8()
+ %t2 = shl i8 1, %bits1
+ %r = icmp ule i8 %t1, %t2
+ ret i1 %r
+}
+
+define i1 @commuted_interference2(i8 %bits0) {
+; CHECK-LABEL: @commuted_interference2(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[BITS1:%.*]] = call i8 @gen8()
+; CHECK-NEXT: [[T2:%.*]] = shl i8 1, [[BITS1]]
+; CHECK-NEXT: [[R:%.*]] = icmp ult i8 [[T2]], [[T1]]
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits0
+ %t1 = xor i8 %t0, -1
+ %bits1 = call i8 @gen8()
+ %t2 = shl i8 1, %bits1
+ %r = icmp ugt i8 %t1, %t2
+ ret i1 %r
+}
+
+define i1 @commuted_interference3(i8 %bits0) {
+; CHECK-LABEL: @commuted_interference3(
+; CHECK-NEXT: [[T0:%.*]] = shl i8 -1, [[BITS0:%.*]]
+; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
+; CHECK-NEXT: [[BITS1:%.*]] = call i8 @gen8()
+; CHECK-NEXT: [[T1_HIGHBITS:%.*]] = lshr i8 [[T1]], [[BITS1]]
+; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1_HIGHBITS]], 0
+; CHECK-NEXT: ret i1 [[R]]
+;
+ %t0 = shl i8 -1, %bits0
+ %t1 = xor i8 %t0, -1
+ %bits1 = call i8 @gen8()
+ %t2 = shl i8 1, %bits1
+ %r = icmp uge i8 %t1, %t2
+ ret i1 %r
+}
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