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[ValueTracking] Pre-commit ComputeNumSignBits test for (shl (zext X), C)
Adding a test case for potential simplifications of (shl (zext X), C) based on number of known sign bits in X.
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‎llvm/test/Analysis/ValueTracking/numsignbits-shl.ll

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
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; RUN: opt -passes=instcombine -S < %s | FileCheck %s
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declare void @escape(i16 %add)
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declare void @escape2(<2 x i16> %add)
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define void @numsignbits_shl_zext(i8 %x) {
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; CHECK-LABEL: define void @numsignbits_shl_zext(
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; CHECK-SAME: i8 [[X:%.*]]) {
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; CHECK-NEXT: [[ASHR:%.*]] = ashr i8 [[X]], 5
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; CHECK-NEXT: [[ZEXT:%.*]] = zext i8 [[ASHR]] to i16
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; CHECK-NEXT: [[NSB4:%.*]] = shl i16 [[ZEXT]], 10
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; CHECK-NEXT: [[AND14:%.*]] = and i16 [[NSB4]], 16384
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; CHECK-NEXT: [[ADD14:%.*]] = add i16 [[AND14]], [[NSB4]]
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; CHECK-NEXT: call void @escape(i16 [[ADD14]])
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; CHECK-NEXT: [[AND13:%.*]] = and i16 [[NSB4]], 8192
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; CHECK-NEXT: [[ADD13:%.*]] = add i16 [[AND13]], [[NSB4]]
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; CHECK-NEXT: call void @escape(i16 [[ADD13]])
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; CHECK-NEXT: [[AND12:%.*]] = and i16 [[NSB4]], 4096
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; CHECK-NEXT: [[ADD12:%.*]] = add i16 [[AND12]], [[NSB4]]
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; CHECK-NEXT: call void @escape(i16 [[ADD12]])
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; CHECK-NEXT: [[AND11:%.*]] = and i16 [[NSB4]], 2048
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; CHECK-NEXT: [[ADD11:%.*]] = add i16 [[AND11]], [[NSB4]]
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; CHECK-NEXT: call void @escape(i16 [[ADD11]])
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; CHECK-NEXT: ret void
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;
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%ashr = ashr i8 %x, 5
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%zext = zext i8 %ashr to i16
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%nsb4 = shl i16 %zext, 10
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; Validate ComputeNumSignBits using this simplification:
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; (A & 2^C1) + A => A & (2^C1 - 1) iff bit C1 in A is a sign bit
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; 4 sign bits: Goal is to fold away the add for bits 12-14.
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%and14 = and i16 %nsb4, 16384
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%add14 = add i16 %and14, %nsb4
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call void @escape(i16 %add14)
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%and13 = and i16 %nsb4, 8192
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%add13 = add i16 %and13, %nsb4
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call void @escape(i16 %add13)
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%and12 = and i16 %nsb4, 4096
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%add12 = add i16 %and12, %nsb4
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call void @escape(i16 %add12)
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%and11 = and i16 %nsb4, 2048
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%add11 = add i16 %and11, %nsb4
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call void @escape(i16 %add11)
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ret void
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}
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define void @numsignbits_shl_zext_shift_amounr_matches_extend(i8 %x) {
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; CHECK-LABEL: define void @numsignbits_shl_zext_shift_amounr_matches_extend(
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; CHECK-SAME: i8 [[X:%.*]]) {
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; CHECK-NEXT: [[ASHR:%.*]] = ashr i8 [[X]], 2
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; CHECK-NEXT: [[ZEXT:%.*]] = zext i8 [[ASHR]] to i16
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; CHECK-NEXT: [[NSB3:%.*]] = shl nuw i16 [[ZEXT]], 8
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; CHECK-NEXT: [[AND14:%.*]] = and i16 [[NSB3]], 16384
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; CHECK-NEXT: [[ADD14:%.*]] = add i16 [[AND14]], [[NSB3]]
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; CHECK-NEXT: call void @escape(i16 [[ADD14]])
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; CHECK-NEXT: [[AND13:%.*]] = and i16 [[NSB3]], 8192
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; CHECK-NEXT: [[ADD13:%.*]] = add i16 [[AND13]], [[NSB3]]
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; CHECK-NEXT: call void @escape(i16 [[ADD13]])
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; CHECK-NEXT: [[AND12:%.*]] = and i16 [[NSB3]], 4096
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; CHECK-NEXT: [[ADD12:%.*]] = add i16 [[AND12]], [[NSB3]]
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; CHECK-NEXT: call void @escape(i16 [[ADD12]])
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; CHECK-NEXT: ret void
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;
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%ashr = ashr i8 %x, 2
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%zext = zext i8 %ashr to i16
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%nsb3 = shl i16 %zext, 8
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; Validate ComputeNumSignBits using this simplification:
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; (A & 2^C1) + A => A & (2^C1 - 1) iff bit C1 in A is a sign bit
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; 3 sign bits: Goal is to fold away the add for bits 13-14.
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%and14 = and i16 %nsb3, 16384
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%add14 = add i16 %and14, %nsb3
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call void @escape(i16 %add14)
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%and13 = and i16 %nsb3, 8192
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%add13 = add i16 %and13, %nsb3
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call void @escape(i16 %add13)
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%and12 = and i16 %nsb3, 4096
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%add12 = add i16 %and12, %nsb3
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call void @escape(i16 %add12)
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ret void
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}
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define void @numsignbits_shl_zext_extended_bits_remains(i8 %x) {
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; CHECK-LABEL: define void @numsignbits_shl_zext_extended_bits_remains(
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; CHECK-SAME: i8 [[X:%.*]]) {
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; CHECK-NEXT: [[ASHR:%.*]] = ashr i8 [[X]], 5
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; CHECK-NEXT: [[ZEXT:%.*]] = zext i8 [[ASHR]] to i16
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; CHECK-NEXT: [[NSB1:%.*]] = shl nuw nsw i16 [[ZEXT]], 7
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; CHECK-NEXT: [[AND14:%.*]] = and i16 [[NSB1]], 16384
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; CHECK-NEXT: [[ADD14:%.*]] = add nuw i16 [[AND14]], [[NSB1]]
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; CHECK-NEXT: call void @escape(i16 [[ADD14]])
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; CHECK-NEXT: ret void
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;
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%ashr = ashr i8 %x, 5
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%zext = zext i8 %ashr to i16
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%nsb1 = shl i16 %zext, 7
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; Validate ComputeNumSignBits using this simplification:
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; (A & 2^C1) + A => A & (2^C1 - 1) iff bit C1 in A is a sign bit
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; 1 sign bit: The add can't be folded away here.
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%and14 = and i16 %nsb1, 16384
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%add14 = add i16 %and14, %nsb1
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call void @escape(i16 %add14)
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ret void
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}
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define void @numsignbits_shl_zext_all_bits_shifted_out(i8 %x) {
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; CHECK-LABEL: define void @numsignbits_shl_zext_all_bits_shifted_out(
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; CHECK-SAME: i8 [[X:%.*]]) {
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; CHECK-NEXT: [[ASHR:%.*]] = lshr i8 [[X]], 5
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; CHECK-NEXT: [[ZEXT:%.*]] = zext nneg i8 [[ASHR]] to i16
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; CHECK-NEXT: [[NSB1:%.*]] = shl i16 [[ZEXT]], 14
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; CHECK-NEXT: [[AND14:%.*]] = and i16 [[NSB1]], 16384
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; CHECK-NEXT: [[ADD14:%.*]] = add i16 [[AND14]], [[NSB1]]
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; CHECK-NEXT: call void @escape(i16 [[ADD14]])
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; CHECK-NEXT: ret void
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;
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%ashr = ashr i8 %x, 5
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%zext = zext i8 %ashr to i16
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%nsb1 = shl i16 %zext, 14
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; Validate ComputeNumSignBits using this simplification:
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; (A & 2^C1) + A => A & (2^C1 - 1) iff bit C1 in A is a sign bit
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; 1 sign bit: The add can't be folded away here.
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%and14 = and i16 %nsb1, 16384
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%add14 = add i16 %and14, %nsb1
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call void @escape(i16 %add14)
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ret void
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}
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define void @numsignbits_shl_zext_vector(<2 x i8> %x) {
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; CHECK-LABEL: define void @numsignbits_shl_zext_vector(
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; CHECK-SAME: <2 x i8> [[X:%.*]]) {
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; CHECK-NEXT: [[ASHR:%.*]] = ashr <2 x i8> [[X]], <i8 5, i8 5>
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; CHECK-NEXT: [[ZEXT:%.*]] = zext <2 x i8> [[ASHR]] to <2 x i16>
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; CHECK-NEXT: [[NSB4:%.*]] = shl <2 x i16> [[ZEXT]], <i16 10, i16 10>
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; CHECK-NEXT: [[AND14:%.*]] = and <2 x i16> [[NSB4]], <i16 16384, i16 16384>
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; CHECK-NEXT: [[ADD14:%.*]] = add <2 x i16> [[AND14]], [[NSB4]]
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; CHECK-NEXT: call void @escape2(<2 x i16> [[ADD14]])
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; CHECK-NEXT: [[AND13:%.*]] = and <2 x i16> [[NSB4]], <i16 8192, i16 8192>
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; CHECK-NEXT: [[ADD13:%.*]] = add <2 x i16> [[AND13]], [[NSB4]]
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; CHECK-NEXT: call void @escape2(<2 x i16> [[ADD13]])
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; CHECK-NEXT: [[AND12:%.*]] = and <2 x i16> [[NSB4]], <i16 4096, i16 4096>
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; CHECK-NEXT: [[ADD12:%.*]] = add <2 x i16> [[AND12]], [[NSB4]]
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; CHECK-NEXT: call void @escape2(<2 x i16> [[ADD12]])
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; CHECK-NEXT: [[AND11:%.*]] = and <2 x i16> [[NSB4]], <i16 2048, i16 2048>
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; CHECK-NEXT: [[ADD11:%.*]] = add <2 x i16> [[AND11]], [[NSB4]]
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; CHECK-NEXT: call void @escape2(<2 x i16> [[ADD11]])
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; CHECK-NEXT: ret void
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;
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%ashr = ashr <2 x i8> %x, <i8 5, i8 5>
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%zext = zext <2 x i8> %ashr to <2 x i16>
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%nsb4 = shl <2 x i16> %zext, <i16 10, i16 10>
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; Validate ComputeNumSignBits using this simplification:
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; (A & 2^C1) + A => A & (2^C1 - 1) iff bit C1 in A is a sign bit
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; 4 sign bits: Goal is to fold away the add for bits 12-14.
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%and14 = and <2 x i16> %nsb4, <i16 16384, i16 16384>
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%add14 = add <2 x i16> %and14, %nsb4
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call void @escape2(<2 x i16> %add14)
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%and13 = and <2 x i16> %nsb4, <i16 8192, i16 8192>
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%add13 = add <2 x i16> %and13, %nsb4
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call void @escape2(<2 x i16> %add13)
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%and12 = and <2 x i16> %nsb4, <i16 4096, i16 4096>
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%add12 = add <2 x i16> %and12, %nsb4
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call void @escape2(<2 x i16> %add12)
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%and11 = and <2 x i16> %nsb4, <i16 2048, i16 2048>
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%add11 = add <2 x i16> %and11, %nsb4
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call void @escape2(<2 x i16> %add11)
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ret void
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}

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