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[GlobalISel] Transform anyext(freeze(trunc(x))) to freeze(x) #165679

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[GlobalISel] Transform anyext(freeze(trunc(x))) to freeze(x) #165679

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28 changes: 20 additions & 8 deletions llvm/include/llvm/Target/GlobalISel/Combine.td
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Original file line number Diff line number Diff line change
Expand Up @@ -805,16 +805,28 @@ def redundant_sext_inreg: GICombineRule <
(defs root:$root),
(match (wip_match_opcode G_SEXT_INREG):$root,
[{ return Helper.matchRedundantSExtInReg(*${root}); }]),
(apply [{ Helper.replaceSingleDefInstWithOperand(*${root}, 1); }])
(apply [{ Helper.replaceSingleDefInstWithOperand(*${root}, 1); }])
>;

// Fold (anyext (trunc x)) -> x if the source type is same as
// the destination type.
// Fold (anyext (trunc x)) -> x if the source type is same as the destination
// type.
def anyext_trunc_fold: GICombineRule <
(defs root:$root, register_matchinfo:$matchinfo),
(match (wip_match_opcode G_ANYEXT):$root,
[{ return Helper.matchCombineAnyExtTrunc(*${root}, ${matchinfo}); }]),
(apply [{ Helper.replaceSingleDefInstWithReg(*${root}, ${matchinfo}); }])
(defs root:$root),
(match (G_TRUNC $x, $src),
(G_ANYEXT $dst, $x):$root,
[{ return MRI.getType(${dst}.getReg()) == MRI.getType(${src}.getReg()); }]),
(apply (GIReplaceReg $dst, $src))
>;

// Fold (anyext (freeze (trunc x))) -> (freeze x) if the source type is same as
// the destination type.
def anyext_freeze_trunc_fold: GICombineRule <
(defs root:$root),
(match (G_TRUNC $x, $src),
(G_FREEZE $y, $x),
(G_ANYEXT $dst, $y):$root,
[{ return MRI.getType(${dst}.getReg()) == MRI.getType(${src}.getReg()); }]),
(apply (G_FREEZE $dst, $src))
>;

// Fold (zext (trunc x)) -> x if the source type is same as the destination type
Expand Down Expand Up @@ -2084,7 +2096,7 @@ def undef_combines : GICombineGroup<[undef_to_fp_zero, undef_to_int_zero,
def identity_combines : GICombineGroup<[select_same_val, right_identity_zero,
binop_same_val, binop_left_to_zero,
binop_right_to_zero, p2i_to_i2p,
i2p_to_p2i, anyext_trunc_fold,
i2p_to_p2i, anyext_trunc_fold, anyext_freeze_trunc_fold,
fneg_fneg_fold, right_identity_one,
add_sub_reg, buildvector_identity_fold,
trunc_buildvector_fold,
Expand Down
25 changes: 21 additions & 4 deletions llvm/test/CodeGen/AArch64/GlobalISel/combine-ext.mir
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Expand Up @@ -385,8 +385,8 @@ body: |
; CHECK: liveins: $h0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s16) = COPY $h0
; CHECK-NEXT: %2:_(s64) = nneg G_ZEXT [[COPY]](s16)
; CHECK-NEXT: $x0 = COPY %2(s64)
; CHECK-NEXT: [[ZEXT:%[0-9]+]]:_(s64) = nneg G_ZEXT [[COPY]](s16)
; CHECK-NEXT: $x0 = COPY [[ZEXT]](s64)
%0:_(s16) = COPY $h0
%1:_(s32) = G_ANYEXT %0(s16)
%2:_(s64) = nneg G_ZEXT %1(s32)
Expand All @@ -401,10 +401,27 @@ body: |
; CHECK: liveins: $h0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s16) = COPY $h0
; CHECK-NEXT: %2:_(s64) = nneg G_ZEXT [[COPY]](s16)
; CHECK-NEXT: $x0 = COPY %2(s64)
; CHECK-NEXT: [[ZEXT:%[0-9]+]]:_(s64) = nneg G_ZEXT [[COPY]](s16)
; CHECK-NEXT: $x0 = COPY [[ZEXT]](s64)
%0:_(s16) = COPY $h0
%1:_(s32) = nneg G_ZEXT %0(s16)
%2:_(s64) = G_ANYEXT %1(s32)
$x0 = COPY %2(s64)
...
---
name: test_combine_anyext_freeze_trunc
body: |
bb.1:
liveins: $x0
; CHECK-LABEL: name: test_combine_anyext_freeze_trunc
; CHECK: liveins: $x0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
; CHECK-NEXT: [[FREEZE:%[0-9]+]]:_(s64) = G_FREEZE [[COPY]]
; CHECK-NEXT: $x1 = COPY [[FREEZE]](s64)
%0:_(s64) = COPY $x0
%1:_(s32) = G_TRUNC %0(s64)
%2:_(s32) = G_FREEZE %1(s32)
%3:_(s64) = G_ANYEXT %2(s32)
$x1 = COPY %3(s64)
...
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Can you add the negative test where the types mismatch? Also test multiple uses of the inner op