Skip to content

[GISel] Fold bitreverse(shl/srl(bitreverse(x),y)) -> srl/shl(x,y) #91355

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
May 8, 2024
+59 −99
Merged

[GISel] Fold bitreverse(shl/srl(bitreverse(x),y)) -> srl/shl(x,y) #91355

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
26 changes: 25 additions & 1 deletion llvm/include/llvm/Target/GlobalISel/Combine.td
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -325,6 +325,28 @@ def reduce_shl_of_extend : GICombineRule<
[{ return Helper.matchCombineShlOfExtend(*${mi}, ${matchinfo}); }]),
(apply [{ Helper.applyCombineShlOfExtend(*${mi}, ${matchinfo}); }])>;

// Combine bitreverse(shl (bitreverse x), y)) -> (lshr x, y)
def bitreverse_shl : GICombineRule<
(defs root:$d),
(match (G_BITREVERSE $rev, $val),
(G_SHL $src, $rev, $amt):$mi,
(G_BITREVERSE $d, $src),
[{ return Helper.isLegalOrBeforeLegalizer({TargetOpcode::G_LSHR,
{MRI.getType(${val}.getReg()),
MRI.getType(${amt}.getReg())}}); }]),
(apply (G_LSHR $d, $val, $amt))>;

// Combine bitreverse(lshr (bitreverse x), y)) -> (shl x, y)
def bitreverse_lshr : GICombineRule<
(defs root:$d, build_fn_matchinfo:$matchinfo),
(match (G_BITREVERSE $rev, $val),
(G_LSHR $src, $rev, $amt):$mi,
(G_BITREVERSE $d, $src),
[{ return Helper.isLegalOrBeforeLegalizer({TargetOpcode::G_SHL,
{MRI.getType(${val}.getReg()),
MRI.getType(${amt}.getReg())}}); }]),
(apply (G_SHL $d, $val, $amt))>;

// Combine (shl (add x, c1), c2) -> (add (shl x, c2), c1 << c2)
// Combine (shl (or x, c1), c2) -> (or (shl x, c2), c1 << c2)
def commute_shift : GICombineRule<
Expand Down Expand Up @@ -1645,6 +1667,8 @@ def width_reduction_combines : GICombineGroup<[reduce_shl_of_extend,

def phi_combines : GICombineGroup<[extend_through_phis]>;

def bitreverse_shift : GICombineGroup<[bitreverse_shl, bitreverse_lshr]>;

def select_combines : GICombineGroup<[select_undef_cmp, select_constant_cmp,
match_selects]>;

Expand Down Expand Up @@ -1674,7 +1698,7 @@ def all_combines : GICombineGroup<[trivial_combines, vector_ops_combines,
unmerge_zext_to_zext, merge_unmerge, trunc_ext_fold, trunc_shift,
const_combines, xor_of_and_with_same_reg, ptr_add_with_zero,
shift_immed_chain, shift_of_shifted_logic_chain, load_or_combine,
div_rem_to_divrem, funnel_shift_combines, commute_shift,
div_rem_to_divrem, funnel_shift_combines, bitreverse_shift, commute_shift,
form_bitfield_extract, constant_fold_binops, constant_fold_fma,
constant_fold_cast_op, fabs_fneg_fold,
intdiv_combines, mulh_combines, redundant_neg_operands,
Expand Down
132 changes: 34 additions & 98 deletions llvm/test/CodeGen/AArch64/GlobalISel/combine-bitreverse-shift.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=aarch64-unknown-unknown | FileCheck %s --check-prefixes=SDAG
; RUN: llc < %s -mtriple=aarch64-unknown-unknown -global-isel | FileCheck %s --check-prefixes=GISEL
; RUN: llc < %s -mtriple=aarch64-unknown-unknown | FileCheck %s
; RUN: llc < %s -mtriple=aarch64-unknown-unknown -global-isel | FileCheck %s

; These tests can be optimised
; fold (bitreverse(srl (bitreverse c), x)) -> (shl c, x)
Expand All @@ -12,151 +12,87 @@ declare i32 @llvm.bitreverse.i32(i32)
declare i64 @llvm.bitreverse.i64(i64)

define i8 @test_bitreverse_srli_bitreverse_i8(i8 %a) nounwind {
; SDAG-LABEL: test_bitreverse_srli_bitreverse_i8:
; SDAG: // %bb.0:
; SDAG-NEXT: lsl w0, w0, #3
; SDAG-NEXT: ret
;
; GISEL-LABEL: test_bitreverse_srli_bitreverse_i8:
; GISEL: // %bb.0:
; GISEL-NEXT: rbit w8, w0
; GISEL-NEXT: lsr w8, w8, #24
; GISEL-NEXT: lsr w8, w8, #3
; GISEL-NEXT: rbit w8, w8
; GISEL-NEXT: lsr w0, w8, #24
; GISEL-NEXT: ret
; CHECK-LABEL: test_bitreverse_srli_bitreverse_i8:
; CHECK: // %bb.0:
; CHECK-NEXT: lsl w0, w0, #3
; CHECK-NEXT: ret
%1 = call i8 @llvm.bitreverse.i8(i8 %a)
%2 = lshr i8 %1, 3
%3 = call i8 @llvm.bitreverse.i8(i8 %2)
ret i8 %3
}

define i16 @test_bitreverse_srli_bitreverse_i16(i16 %a) nounwind {
; SDAG-LABEL: test_bitreverse_srli_bitreverse_i16:
; SDAG: // %bb.0:
; SDAG-NEXT: lsl w0, w0, #7
; SDAG-NEXT: ret
;
; GISEL-LABEL: test_bitreverse_srli_bitreverse_i16:
; GISEL: // %bb.0:
; GISEL-NEXT: rbit w8, w0
; GISEL-NEXT: lsr w8, w8, #16
; GISEL-NEXT: lsr w8, w8, #7
; GISEL-NEXT: rbit w8, w8
; GISEL-NEXT: lsr w0, w8, #16
; GISEL-NEXT: ret
; CHECK-LABEL: test_bitreverse_srli_bitreverse_i16:
; CHECK: // %bb.0:
; CHECK-NEXT: lsl w0, w0, #7
; CHECK-NEXT: ret
%1 = call i16 @llvm.bitreverse.i16(i16 %a)
%2 = lshr i16 %1, 7
%3 = call i16 @llvm.bitreverse.i16(i16 %2)
ret i16 %3
}

define i32 @test_bitreverse_srli_bitreverse_i32(i32 %a) nounwind {
; SDAG-LABEL: test_bitreverse_srli_bitreverse_i32:
; SDAG: // %bb.0:
; SDAG-NEXT: lsl w0, w0, #15
; SDAG-NEXT: ret
;
; GISEL-LABEL: test_bitreverse_srli_bitreverse_i32:
; GISEL: // %bb.0:
; GISEL-NEXT: rbit w8, w0
; GISEL-NEXT: lsr w8, w8, #15
; GISEL-NEXT: rbit w0, w8
; GISEL-NEXT: ret
; CHECK-LABEL: test_bitreverse_srli_bitreverse_i32:
; CHECK: // %bb.0:
; CHECK-NEXT: lsl w0, w0, #15
; CHECK-NEXT: ret
%1 = call i32 @llvm.bitreverse.i32(i32 %a)
%2 = lshr i32 %1, 15
%3 = call i32 @llvm.bitreverse.i32(i32 %2)
ret i32 %3
}

define i64 @test_bitreverse_srli_bitreverse_i64(i64 %a) nounwind {
; SDAG-LABEL: test_bitreverse_srli_bitreverse_i64:
; SDAG: // %bb.0:
; SDAG-NEXT: lsl x0, x0, #33
; SDAG-NEXT: ret
;
; GISEL-LABEL: test_bitreverse_srli_bitreverse_i64:
; GISEL: // %bb.0:
; GISEL-NEXT: rbit x8, x0
; GISEL-NEXT: lsr x8, x8, #33
; GISEL-NEXT: rbit x0, x8
; GISEL-NEXT: ret
; CHECK-LABEL: test_bitreverse_srli_bitreverse_i64:
; CHECK: // %bb.0:
; CHECK-NEXT: lsl x0, x0, #33
; CHECK-NEXT: ret
%1 = call i64 @llvm.bitreverse.i64(i64 %a)
%2 = lshr i64 %1, 33
%3 = call i64 @llvm.bitreverse.i64(i64 %2)
ret i64 %3
}

define i8 @test_bitreverse_shli_bitreverse_i8(i8 %a) nounwind {
; SDAG-LABEL: test_bitreverse_shli_bitreverse_i8:
; SDAG: // %bb.0:
; SDAG-NEXT: ubfx w0, w0, #3, #5
; SDAG-NEXT: ret
;
; GISEL-LABEL: test_bitreverse_shli_bitreverse_i8:
; GISEL: // %bb.0:
; GISEL-NEXT: rbit w8, w0
; GISEL-NEXT: lsr w8, w8, #24
; GISEL-NEXT: lsl w8, w8, #3
; GISEL-NEXT: rbit w8, w8
; GISEL-NEXT: lsr w0, w8, #24
; GISEL-NEXT: ret
; CHECK-LABEL: test_bitreverse_shli_bitreverse_i8:
; CHECK: // %bb.0:
; CHECK-NEXT: ubfx w0, w0, #3, #5
; CHECK-NEXT: ret
%1 = call i8 @llvm.bitreverse.i8(i8 %a)
%2 = shl i8 %1, 3
%3 = call i8 @llvm.bitreverse.i8(i8 %2)
ret i8 %3
}

define i16 @test_bitreverse_shli_bitreverse_i16(i16 %a) nounwind {
; SDAG-LABEL: test_bitreverse_shli_bitreverse_i16:
; SDAG: // %bb.0:
; SDAG-NEXT: ubfx w0, w0, #7, #9
; SDAG-NEXT: ret
;
; GISEL-LABEL: test_bitreverse_shli_bitreverse_i16:
; GISEL: // %bb.0:
; GISEL-NEXT: rbit w8, w0
; GISEL-NEXT: lsr w8, w8, #16
; GISEL-NEXT: lsl w8, w8, #7
; GISEL-NEXT: rbit w8, w8
; GISEL-NEXT: lsr w0, w8, #16
; GISEL-NEXT: ret
; CHECK-LABEL: test_bitreverse_shli_bitreverse_i16:
; CHECK: // %bb.0:
; CHECK-NEXT: ubfx w0, w0, #7, #9
; CHECK-NEXT: ret
%1 = call i16 @llvm.bitreverse.i16(i16 %a)
%2 = shl i16 %1, 7
%3 = call i16 @llvm.bitreverse.i16(i16 %2)
ret i16 %3
}

define i32 @test_bitreverse_shli_bitreverse_i32(i32 %a) nounwind {
; SDAG-LABEL: test_bitreverse_shli_bitreverse_i32:
; SDAG: // %bb.0:
; SDAG-NEXT: lsr w0, w0, #15
; SDAG-NEXT: ret
;
; GISEL-LABEL: test_bitreverse_shli_bitreverse_i32:
; GISEL: // %bb.0:
; GISEL-NEXT: rbit w8, w0
; GISEL-NEXT: lsl w8, w8, #15
; GISEL-NEXT: rbit w0, w8
; GISEL-NEXT: ret
; CHECK-LABEL: test_bitreverse_shli_bitreverse_i32:
; CHECK: // %bb.0:
; CHECK-NEXT: lsr w0, w0, #15
; CHECK-NEXT: ret
%1 = call i32 @llvm.bitreverse.i32(i32 %a)
%2 = shl i32 %1, 15
%3 = call i32 @llvm.bitreverse.i32(i32 %2)
ret i32 %3
}

define i64 @test_bitreverse_shli_bitreverse_i64(i64 %a) nounwind {
; SDAG-LABEL: test_bitreverse_shli_bitreverse_i64:
; SDAG: // %bb.0:
; SDAG-NEXT: lsr x0, x0, #33
; SDAG-NEXT: ret
;
; GISEL-LABEL: test_bitreverse_shli_bitreverse_i64:
; GISEL: // %bb.0:
; GISEL-NEXT: rbit x8, x0
; GISEL-NEXT: lsl x8, x8, #33
; GISEL-NEXT: rbit x0, x8
; GISEL-NEXT: ret
; CHECK-LABEL: test_bitreverse_shli_bitreverse_i64:
; CHECK: // %bb.0:
; CHECK-NEXT: lsr x0, x0, #33
; CHECK-NEXT: ret
%1 = call i64 @llvm.bitreverse.i64(i64 %a)
%2 = shl i64 %1, 33
%3 = call i64 @llvm.bitreverse.i64(i64 %2)
Expand Down