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[InstCombine] add test for faulty cttz fold (PR45762); NFC

This commit is contained in:
Sanjay Patel 2020-05-01 12:53:57 -04:00
parent 68fb8051d0
commit 43b0e446fb
1 changed files with 31 additions and 1 deletions
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32
llvm/test/Transforms/InstCombine/select-ctlz-to-cttz.ll
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@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -instcombine -S < %s | FileCheck %s
declare i3 @llvm.cttz.i3(i3, i1)
declare i32 @llvm.cttz.i32(i32, i1 immarg)
declare i32 @llvm.ctlz.i32(i32, i1 immarg)
declare i64 @llvm.cttz.i64(i64, i1 immarg)
@ -217,3 +217,33 @@ define <2 x i32> @select_clz_to_ctz_vec_with_undef(<2 x i32> %a) {
%cond = select <2 x i1> %tobool, <2 x i32> %lz, <2 x i32> %sub1
ret <2 x i32> %cond
}
define i4 @PR45762(i3 %x4) {
; CHECK-LABEL: @PR45762(
; CHECK-NEXT: [[T4:%.*]] = call i3 @llvm.cttz.i3(i3 [[X4:%.*]], i1 true), !range !2
; CHECK-NEXT: [[T7:%.*]] = zext i3 [[T4]] to i4
; CHECK-NEXT: [[ONE_HOT_16:%.*]] = shl i4 1, [[T7]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i3 [[X4]], 0
; CHECK-NEXT: [[NARROW:%.*]] = select i1 [[TMP1]], i3 0, i3 [[T4]]
; CHECK-NEXT: [[UMUL_23:%.*]] = zext i3 [[NARROW]] to i4
; CHECK-NEXT: [[SEL_71:%.*]] = shl i4 [[ONE_HOT_16]], [[UMUL_23]]
; CHECK-NEXT: ret i4 [[SEL_71]]
;
%t4 = call i3 @llvm.cttz.i3(i3 %x4, i1 false)
%t5 = icmp eq i3 %x4, 0
%t6 = select i1 %t5, i3 3, i3 %t4
%t7 = zext i3 %t6 to i4
%one_hot_16 = shl i4 1, %t7
%t8 = lshr i4 %one_hot_16, 0
%bit_slice_61 = trunc i4 %t8 to i1
%t9 = lshr i4 %one_hot_16, 1
%bit_slice_62 = trunc i4 %t9 to i1
%t10 = lshr i4 %one_hot_16, 2
%bit_slice_64 = trunc i4 %t10 to i1
%t11 = or i1 %bit_slice_61, %bit_slice_62
%or_69 = or i1 %t11, %bit_slice_64
%umul_23 = mul i4 %one_hot_16, %one_hot_16
%t12 = icmp eq i1 %or_69, false
%sel_71 = select i1 %t12, i4 %one_hot_16, i4 %umul_23
ret i4 %sel_71
}