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llvm-mirror/test/Transforms/InstSimplify/icmp-abs-nabs.ll
Craig Topper 3d068e1b37 [ValueTracking] When calculating known bits for integer abs, make sure we're looking at a negate and not just any instruction with the nsw flag set.
The matchSelectPattern code can match patterns like (x >= 0) ? x : -x
for absolute value. But it can also match ((x-y) >= 0) ? (x-y) : (y-x).
If the latter form was matched we can only use the nsw flag if its
set on both subtracts.

This match makes sure we're looking at the former case only.

Differential Revision: https://reviews.llvm.org/D65692

llvm-svn: 368195
2019-08-07 18:28:16 +00:00

421 lines
12 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instsimplify -S | FileCheck %s
; This is canonical form for this IR.
define i1 @abs_nsw_is_positive(i32 %x) {
; CHECK-LABEL: @abs_nsw_is_positive(
; CHECK-NEXT: ret i1 true
;
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp sgt i32 %abs, -1
ret i1 %r
}
; Test non-canonical predicate and non-canonical form of abs().
define i1 @abs_nsw_is_positive_sge(i32 %x) {
; CHECK-LABEL: @abs_nsw_is_positive_sge(
; CHECK-NEXT: ret i1 true
;
%cmp = icmp slt i32 %x, 1
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp sge i32 %abs, 0
ret i1 %r
}
; This is a range-based analysis. Any negative constant works.
define i1 @abs_nsw_is_positive_reduced_range(i32 %x) {
; CHECK-LABEL: @abs_nsw_is_positive_reduced_range(
; CHECK-NEXT: ret i1 true
;
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp sgt i32 %abs, -42
ret i1 %r
}
; Negative test - we need 'nsw' in the abs().
define i1 @abs_is_positive_reduced_range(i32 %x) {
; CHECK-LABEL: @abs_is_positive_reduced_range(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 0
; CHECK-NEXT: [[NEGX:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[NEGX]], i32 [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt i32 [[ABS]], 42
; CHECK-NEXT: ret i1 [[R]]
;
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp sgt i32 %abs, 42
ret i1 %r
}
; Negative test - range intersection is not subset.
define i1 @abs_nsw_is_positive_wrong_range(i32 %x) {
; CHECK-LABEL: @abs_nsw_is_positive_wrong_range(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 0
; CHECK-NEXT: [[NEGX:%.*]] = sub nsw i32 0, [[X]]
; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[NEGX]], i32 [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt i32 [[ABS]], 0
; CHECK-NEXT: ret i1 [[R]]
;
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp sgt i32 %abs, 0
ret i1 %r
}
; This is canonical form for this IR.
define i1 @abs_nsw_is_not_negative(i32 %x) {
; CHECK-LABEL: @abs_nsw_is_not_negative(
; CHECK-NEXT: ret i1 false
;
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp slt i32 %abs, 0
ret i1 %r
}
; Test non-canonical predicate and non-canonical form of abs().
define i1 @abs_nsw_is_not_negative_sle(i32 %x) {
; CHECK-LABEL: @abs_nsw_is_not_negative_sle(
; CHECK-NEXT: ret i1 false
;
%cmp = icmp slt i32 %x, 1
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp sle i32 %abs, -1
ret i1 %r
}
; This is a range-based analysis. Any negative constant works.
define i1 @abs_nsw_is_not_negative_reduced_range(i32 %x) {
; CHECK-LABEL: @abs_nsw_is_not_negative_reduced_range(
; CHECK-NEXT: ret i1 false
;
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp slt i32 %abs, -24
ret i1 %r
}
; Negative test - we need 'nsw' in the abs().
define i1 @abs_is_not_negative_reduced_range(i32 %x) {
; CHECK-LABEL: @abs_is_not_negative_reduced_range(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 0
; CHECK-NEXT: [[NEGX:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[NEGX]], i32 [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp slt i32 [[ABS]], 42
; CHECK-NEXT: ret i1 [[R]]
;
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp slt i32 %abs, 42
ret i1 %r
}
; Negative test - range intersection is not empty.
define i1 @abs_nsw_is_not_negative_wrong_range(i32 %x) {
; CHECK-LABEL: @abs_nsw_is_not_negative_wrong_range(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 0
; CHECK-NEXT: [[NEGX:%.*]] = sub nsw i32 0, [[X]]
; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[NEGX]], i32 [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp sle i32 [[ABS]], 0
; CHECK-NEXT: ret i1 [[R]]
;
%cmp = icmp slt i32 %x, 0
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp sle i32 %abs, 0
ret i1 %r
}
; Even if we don't have nsw, the range is still limited in the unsigned domain.
define i1 @abs_positive_or_signed_min(i32 %x) {
; CHECK-LABEL: @abs_positive_or_signed_min(
; CHECK-NEXT: ret i1 true
;
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp ult i32 %abs, 2147483649
ret i1 %r
}
define i1 @abs_positive_or_signed_min_reduced_range(i32 %x) {
; CHECK-LABEL: @abs_positive_or_signed_min_reduced_range(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 0
; CHECK-NEXT: [[NEGX:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[ABS:%.*]] = select i1 [[CMP]], i32 [[NEGX]], i32 [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp ult i32 [[ABS]], -2147483648
; CHECK-NEXT: ret i1 [[R]]
;
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp ult i32 %abs, 2147483648
ret i1 %r
}
; This is canonical form for this IR. For nabs(), we don't require 'nsw'
define i1 @nabs_is_negative_or_0(i32 %x) {
; CHECK-LABEL: @nabs_is_negative_or_0(
; CHECK-NEXT: ret i1 true
;
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp slt i32 %nabs, 1
ret i1 %r
}
; Test non-canonical predicate and non-canonical form of nabs().
define i1 @nabs_is_negative_or_0_sle(i32 %x) {
; CHECK-LABEL: @nabs_is_negative_or_0_sle(
; CHECK-NEXT: ret i1 true
;
%cmp = icmp slt i32 %x, 1
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp sle i32 %nabs, 0
ret i1 %r
}
; This is a range-based analysis. Any positive constant works.
define i1 @nabs_is_negative_or_0_reduced_range(i32 %x) {
; CHECK-LABEL: @nabs_is_negative_or_0_reduced_range(
; CHECK-NEXT: ret i1 true
;
%cmp = icmp slt i32 %x, 1
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp slt i32 %nabs, 421
ret i1 %r
}
; Negative test - range intersection is not subset.
define i1 @nabs_is_negative_or_0_wrong_range(i32 %x) {
; CHECK-LABEL: @nabs_is_negative_or_0_wrong_range(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 1
; CHECK-NEXT: [[NEGX:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[NABS:%.*]] = select i1 [[CMP]], i32 [[X]], i32 [[NEGX]]
; CHECK-NEXT: [[R:%.*]] = icmp slt i32 [[NABS]], 0
; CHECK-NEXT: ret i1 [[R]]
;
%cmp = icmp slt i32 %x, 1
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp slt i32 %nabs, 0
ret i1 %r
}
; This is canonical form for this IR. For nabs(), we don't require 'nsw'
define i1 @nabs_is_not_over_0(i32 %x) {
; CHECK-LABEL: @nabs_is_not_over_0(
; CHECK-NEXT: ret i1 false
;
%cmp = icmp slt i32 %x, 0
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp sgt i32 %nabs, 0
ret i1 %r
}
; Test non-canonical predicate and non-canonical form of nabs().
define i1 @nabs_is_not_over_0_sle(i32 %x) {
; CHECK-LABEL: @nabs_is_not_over_0_sle(
; CHECK-NEXT: ret i1 false
;
%cmp = icmp slt i32 %x, 1
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp sge i32 %nabs, 1
ret i1 %r
}
; This is a range-based analysis. Any positive constant works.
define i1 @nabs_is_not_over_0_reduced_range(i32 %x) {
; CHECK-LABEL: @nabs_is_not_over_0_reduced_range(
; CHECK-NEXT: ret i1 false
;
%cmp = icmp slt i32 %x, 1
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp sgt i32 %nabs, 4223
ret i1 %r
}
; Negative test - range intersection is not subset.
define i1 @nabs_is_not_over_0_wrong_range(i32 %x) {
; CHECK-LABEL: @nabs_is_not_over_0_wrong_range(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[X:%.*]], 1
; CHECK-NEXT: [[NEGX:%.*]] = sub i32 0, [[X]]
; CHECK-NEXT: [[NABS:%.*]] = select i1 [[CMP]], i32 [[X]], i32 [[NEGX]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt i32 [[NABS]], -1
; CHECK-NEXT: ret i1 [[R]]
;
%cmp = icmp slt i32 %x, 1
%negx = sub i32 0, %x
%nabs = select i1 %cmp, i32 %x, i32 %negx
%r = icmp sgt i32 %nabs, -1
ret i1 %r
}
; More miscellaneous tests for predicates/types.
; Equality predicates are ok.
define i1 @abs_nsw_is_positive_eq(i32 %x) {
; CHECK-LABEL: @abs_nsw_is_positive_eq(
; CHECK-NEXT: ret i1 false
;
%cmp = icmp slt i32 %x, 1
%negx = sub nsw i32 0, %x
%abs = select i1 %cmp, i32 %negx, i32 %x
%r = icmp eq i32 %abs, -8
ret i1 %r
}
; An unsigned compare may work.
define i1 @abs_nsw_is_positive_ult(i8 %x) {
; CHECK-LABEL: @abs_nsw_is_positive_ult(
; CHECK-NEXT: ret i1 true
;
%cmp = icmp slt i8 %x, 0
%negx = sub nsw i8 0, %x
%abs = select i1 %cmp, i8 %negx, i8 %x
%r = icmp ult i8 %abs, 139
ret i1 %r
}
; An unsigned compare may work.
define i1 @abs_nsw_is_not_negative_ugt(i8 %x) {
; CHECK-LABEL: @abs_nsw_is_not_negative_ugt(
; CHECK-NEXT: ret i1 false
;
%cmp = icmp slt i8 %x, 0
%negx = sub nsw i8 0, %x
%abs = select i1 %cmp, i8 %negx, i8 %x
%r = icmp ugt i8 %abs, 127
ret i1 %r
}
; Vector types are ok.
define <2 x i1> @abs_nsw_is_not_negative_vec_splat(<2 x i32> %x) {
; CHECK-LABEL: @abs_nsw_is_not_negative_vec_splat(
; CHECK-NEXT: ret <2 x i1> zeroinitializer
;
%cmp = icmp slt <2 x i32> %x, zeroinitializer
%negx = sub nsw <2 x i32> zeroinitializer, %x
%abs = select <2 x i1> %cmp, <2 x i32> %negx, <2 x i32> %x
%r = icmp slt <2 x i32> %abs, <i32 -8, i32 -8>
ret <2 x i1> %r
}
; Equality predicates are ok.
define i1 @nabs_is_negative_or_0_ne(i8 %x) {
; CHECK-LABEL: @nabs_is_negative_or_0_ne(
; CHECK-NEXT: ret i1 true
;
%cmp = icmp slt i8 %x, 0
%negx = sub i8 0, %x
%nabs = select i1 %cmp, i8 %x, i8 %negx
%r = icmp ne i8 %nabs, 12
ret i1 %r
}
; Vector types are ok.
define <3 x i1> @nabs_is_not_over_0_sle_vec_splat(<3 x i33> %x) {
; CHECK-LABEL: @nabs_is_not_over_0_sle_vec_splat(
; CHECK-NEXT: ret <3 x i1> zeroinitializer
;
%cmp = icmp slt <3 x i33> %x, <i33 1, i33 1, i33 1>
%negx = sub <3 x i33> zeroinitializer, %x
%nabs = select <3 x i1> %cmp, <3 x i33> %x, <3 x i33> %negx
%r = icmp sge <3 x i33> %nabs, <i33 1, i33 1, i33 1>
ret <3 x i1> %r
}
; Negative test - intersection does not equal absolute value range.
; PR39510 - https://bugs.llvm.org/show_bug.cgi?id=39510
define i1 @abs_no_intersection(i32 %a) {
; CHECK-LABEL: @abs_no_intersection(
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[A:%.*]], 0
; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 0, [[A]]
; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 [[A]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i32 [[COND]], 2
; CHECK-NEXT: ret i1 [[R]]
;
%cmp = icmp slt i32 %a, 0
%sub = sub nsw i32 0, %a
%cond = select i1 %cmp, i32 %sub, i32 %a
%r = icmp ne i32 %cond, 2
ret i1 %r
}
; Negative test - intersection does not equal absolute value range.
define i1 @nabs_no_intersection(i32 %a) {
; CHECK-LABEL: @nabs_no_intersection(
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 0
; CHECK-NEXT: [[SUB:%.*]] = sub i32 0, [[A]]
; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 [[A]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i32 [[COND]], -2
; CHECK-NEXT: ret i1 [[R]]
;
%cmp = icmp sgt i32 %a, 0
%sub = sub i32 0, %a
%cond = select i1 %cmp, i32 %sub, i32 %a
%r = icmp ne i32 %cond, -2
ret i1 %r
}
; We can't fold this to false unless both subs have nsw.
define i1 @abs_sub_sub_missing_nsw(i32 %x, i32 %y) {
; CHECK-LABEL: @abs_sub_sub_missing_nsw(
; CHECK-NEXT: [[A:%.*]] = sub i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[B:%.*]] = sub nsw i32 [[Y]], [[X]]
; CHECK-NEXT: [[C:%.*]] = icmp sgt i32 [[A]], -1
; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[A]], i32 [[B]]
; CHECK-NEXT: [[E:%.*]] = icmp slt i32 [[D]], 0
; CHECK-NEXT: ret i1 [[E]]
;
%a = sub i32 %x, %y
%b = sub nsw i32 %y, %x
%c = icmp sgt i32 %a, -1
%d = select i1 %c, i32 %a, i32 %b
%e = icmp slt i32 %d, 0
ret i1 %e
}