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[InstCombine] Add tests for missing fold icmp pred (and X, (sh signbit, Y)), 0.
AbandonedPublic

Authored by huihuiz on Jun 7 2019, 2:32 PM.

Reviewers

Summary

Expect to fold:

(X & (signbit l>> Y)) ==/!= 0 -> (X << Y) >=/< 0
(X & (signbit << Y)) ==/!= 0 -> (X l>> Y) >=/< 0

split from D62818

test cases added in D63025

Path

Size

test/

Transforms/

InstCombine/

32 lines

				; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
				; RUN: opt %s -instcombine -S \| FileCheck %s


				; FIXME: expect (X & (signbit l>> Y)) ==/!= 0 -> (X << Y) >=/< 0
				define i1 @signbit-lshr-and(i32 %x, i32 %y) {
				; CHECK-LABEL: @signbit-lshr-and(
				; CHECK-NEXT: [[LSHR:%.]] = lshr i32 -2147483648, [[Y:%.]]
				; CHECK-NEXT: [[AND:%.]] = and i32 [[LSHR]], [[X:%.]]
				; CHECK-NEXT: [[R:%.*]] = icmp ne i32 [[AND]], 0
				; CHECK-NEXT: ret i1 [[R]]
				;
				%lshr = lshr i32 -2147483648, %y
				%and = and i32 %lshr, %x
				%r = icmp ne i32 %and, 0
				ret i1 %r
				}

				; FIXME: expect (X & (signbit << Y)) ==/!= 0 -> (X l>> Y) >=/< 0
				define i1 @signbit-shl-and(i32 %x, i32 %y) {
				; CHECK-LABEL: @signbit-shl-and(
				; CHECK-NEXT: [[SHL:%.]] = shl i32 -2147483648, [[Y:%.]]
				; CHECK-NEXT: [[AND:%.]] = and i32 [[SHL]], [[X:%.]]
				; CHECK-NEXT: [[R:%.*]] = icmp eq i32 [[AND]], 0
				; CHECK-NEXT: ret i1 [[R]]
				;
				%shl = shl i32 -2147483648, %y
				%and = and i32 %shl, %x
				%r = icmp eq i32 %and, 0
				ret i1 %r
				}