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Differential D80094

GlobalISel: Fold G_MUL x, 0, and G_*DIV 0, x
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Authored by arsenm on May 17 2020, 5:12 PM.

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paquette

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arsenm created this revision.May 17 2020, 5:12 PM
Herald added a project: Restricted Project. · View Herald TranscriptMay 17 2020, 5:12 PM
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paquette accepted this revision.May 18 2020, 9:54 AM

LGTM

This revision is now accepted and ready to land.May 18 2020, 9:54 AM
arsenm closed this revision.May 18 2020, 3:08 PM

ae989391723478c6e8c61b68dd4c575798f340db

mkitzan mentioned this in D87870: [GISel] Add new combines for G_FMUL.Sep 18 2020, 3:10 PM

Revision Contents

PathSize
llvm/
include/
llvm/
CodeGen/
GlobalISel/
3 lines
Target/
GlobalISel/
19 lines
lib/
CodeGen/
GlobalISel/
6 lines
test/
CodeGen/
AArch64/
GlobalISel/
126 lines

Diff 264520

llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h

Show First 20 Lines • Show All 225 Lines • ▼ Show 20 Linespublic:
bool matchConstantOp(const MachineOperand &MOP, int64_t C); bool matchConstantOp(const MachineOperand &MOP, int64_t C);
/// Optimize (cond ? x : x) -> x /// Optimize (cond ? x : x) -> x
bool matchSelectSameVal(MachineInstr &MI); bool matchSelectSameVal(MachineInstr &MI);
/// Optimize (x op x) -> x /// Optimize (x op x) -> x
bool matchBinOpSameVal(MachineInstr &MI); bool matchBinOpSameVal(MachineInstr &MI);
/// Check if operand \p OpIdx is zero.
bool matchOperandIsZero(MachineInstr &MI, unsigned OpIdx);
/// Try to transform \p MI by using all of the above /// Try to transform \p MI by using all of the above
/// combine functions. Returns true if changed. /// combine functions. Returns true if changed.
bool tryCombine(MachineInstr &MI); bool tryCombine(MachineInstr &MI);
private: private:
// Memcpy family optimization helpers. // Memcpy family optimization helpers.
bool optimizeMemcpy(MachineInstr &MI, Register Dst, Register Src, bool optimizeMemcpy(MachineInstr &MI, Register Dst, Register Src,
unsigned KnownLen, Align DstAlign, Align SrcAlign, unsigned KnownLen, Align DstAlign, Align SrcAlign,
Show All 24 Lines

llvm/include/llvm/Target/GlobalISel/Combine.td

Show First 20 Lines • Show All 202 Lines • ▼ Show 20 Lines
// Fold (x op x) - > x // Fold (x op x) - > x
def binop_same_val: GICombineRule< def binop_same_val: GICombineRule<
(defs root:$root), (defs root:$root),
(match (wip_match_opcode G_AND, G_OR):$root, (match (wip_match_opcode G_AND, G_OR):$root,
[{ return Helper.matchBinOpSameVal(*${root}); }]), [{ return Helper.matchBinOpSameVal(*${root}); }]),
(apply [{ return Helper.replaceSingleDefInstWithOperand(*${root}, 1); }]) (apply [{ return Helper.replaceSingleDefInstWithOperand(*${root}, 1); }])
>; >;
// Fold (0 op x) - > 0
def binop_left_to_zero: GICombineRule<
(defs root:$root),
(match (wip_match_opcode G_SDIV, G_UDIV, G_SREM, G_UREM):$root,
[{ return Helper.matchOperandIsZero(*${root}, 1); }]),
(apply [{ return Helper.replaceSingleDefInstWithOperand(*${root}, 1); }])
>;
// Fold (x op 0) - > 0
def binop_right_to_zero: GICombineRule<
(defs root:$root),
(match (wip_match_opcode G_MUL):$root,
[{ return Helper.matchOperandIsZero(*${root}, 2); }]),
(apply [{ return Helper.replaceSingleDefInstWithOperand(*${root}, 2); }])
>;
// FIXME: These should use the custom predicate feature once it lands. // FIXME: These should use the custom predicate feature once it lands.
def undef_combines : GICombineGroup<[undef_to_fp_zero, undef_to_int_zero, def undef_combines : GICombineGroup<[undef_to_fp_zero, undef_to_int_zero,
undef_to_negative_one, undef_to_negative_one,
propagate_undef_any_op, propagate_undef_any_op,
propagate_undef_all_ops, propagate_undef_all_ops,
propagate_undef_shuffle_mask]>; propagate_undef_shuffle_mask]>;
def identity_combines : GICombineGroup<[select_same_val, right_identity_zero, def identity_combines : GICombineGroup<[select_same_val, right_identity_zero,
binop_same_val]>; binop_same_val, binop_left_to_zero,
binop_right_to_zero]>;
def trivial_combines : GICombineGroup<[copy_prop, mul_to_shl]>; def trivial_combines : GICombineGroup<[copy_prop, mul_to_shl]>;
def all_combines : GICombineGroup<[trivial_combines, ptr_add_immed_chain, def all_combines : GICombineGroup<[trivial_combines, ptr_add_immed_chain,
combines_for_extload, combine_indexed_load_store, undef_combines, combines_for_extload, combine_indexed_load_store, undef_combines,
identity_combines]>; identity_combines]>;

llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp

Show First 20 Lines • Show All 1,581 Lines • ▼ Show 20 Lines
} }
bool CombinerHelper::matchBinOpSameVal(MachineInstr &MI) { bool CombinerHelper::matchBinOpSameVal(MachineInstr &MI) {
return matchEqualDefs(MI.getOperand(1), MI.getOperand(2)) && return matchEqualDefs(MI.getOperand(1), MI.getOperand(2)) &&
canReplaceReg(MI.getOperand(0).getReg(), MI.getOperand(1).getReg(), canReplaceReg(MI.getOperand(0).getReg(), MI.getOperand(1).getReg(),
MRI); MRI);
} }
bool CombinerHelper::matchOperandIsZero(MachineInstr &MI, unsigned OpIdx) {
return matchConstantOp(MI.getOperand(OpIdx), 0) &&
canReplaceReg(MI.getOperand(0).getReg(), MI.getOperand(OpIdx).getReg(),
MRI);
}
bool CombinerHelper::replaceInstWithFConstant(MachineInstr &MI, double C) { bool CombinerHelper::replaceInstWithFConstant(MachineInstr &MI, double C) {
assert(MI.getNumDefs() == 1 && "Expected only one def?"); assert(MI.getNumDefs() == 1 && "Expected only one def?");
Builder.setInstr(MI); Builder.setInstr(MI);
Builder.buildFConstant(MI.getOperand(0), C); Builder.buildFConstant(MI.getOperand(0), C);
MI.eraseFromParent(); MI.eraseFromParent();
return true; return true;
} }
Show All 25 Lines

llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-trivial-arith.mir

Show All 35 Lines bb.1.entry:
%x:_(s32) = COPY $w0 %x:_(s32) = COPY $w0
%cst:_(s32) = G_CONSTANT i32 0 %cst:_(s32) = G_CONSTANT i32 0
%op:_(s32) = G_ADD %x(s32), %cst %op:_(s32) = G_ADD %x(s32), %cst
$w0 = COPY %op(s32) $w0 = COPY %op(s32)
RET_ReallyLR implicit $w0 RET_ReallyLR implicit $w0
... ...
--- ---
name: mul_0
tracksRegLiveness: true
body: |
bb.1.entry:
liveins: $w0
; Fold (x * 0) -> 0
;
; CHECK-LABEL: name: mul_0
; CHECK: liveins: $w0
; CHECK: %cst:_(s32) = G_CONSTANT i32 0
; CHECK: $w0 = COPY %cst(s32)
; CHECK: RET_ReallyLR implicit $w0
%x:_(s32) = COPY $w0
%cst:_(s32) = G_CONSTANT i32 0
%op:_(s32) = G_MUL %x(s32), %cst
$w0 = COPY %op(s32)
RET_ReallyLR implicit $w0
...
# FIXME: Probably should be able to replace this.
---
name: mul_0_cant_replace
tracksRegLiveness: true
body: |
bb.1.entry:
liveins: $w0
; Fold (x * 0) -> 0
;
; CHECK-LABEL: name: mul_0_cant_replace
; CHECK: liveins: $w0
; CHECK: %x:_(s32) = COPY $w0
; CHECK: %cst:_(s32) = G_CONSTANT i32 0
; CHECK: %op:gpr(s32) = G_MUL %x, %cst
; CHECK: $w0 = COPY %op(s32)
; CHECK: RET_ReallyLR implicit $w0
%x:_(s32) = COPY $w0
%cst:_(s32) = G_CONSTANT i32 0
%op:gpr(s32) = G_MUL %x(s32), %cst
$w0 = COPY %op(s32)
RET_ReallyLR implicit $w0
...
---
name: sdiv_0
tracksRegLiveness: true
body: |
bb.1.entry:
liveins: $w0
; Fold (0 / x) -> 0
;
; CHECK-LABEL: name: sdiv_0
; CHECK: liveins: $w0
; CHECK: %cst:_(s32) = G_CONSTANT i32 0
; CHECK: $w0 = COPY %cst(s32)
; CHECK: RET_ReallyLR implicit $w0
%x:_(s32) = COPY $w0
%cst:_(s32) = G_CONSTANT i32 0
%op:_(s32) = G_SDIV %cst, %x
$w0 = COPY %op(s32)
RET_ReallyLR implicit $w0
...
---
name: udiv_0
tracksRegLiveness: true
body: |
bb.1.entry:
liveins: $w0
; Fold (0 / x) -> 0
;
; CHECK-LABEL: name: udiv_0
; CHECK: liveins: $w0
; CHECK: %cst:_(s32) = G_CONSTANT i32 0
; CHECK: $w0 = COPY %cst(s32)
; CHECK: RET_ReallyLR implicit $w0
%x:_(s32) = COPY $w0
%cst:_(s32) = G_CONSTANT i32 0
%op:_(s32) = G_UDIV %cst, %x
$w0 = COPY %op(s32)
RET_ReallyLR implicit $w0
...
---
name: srem_0
tracksRegLiveness: true
body: |
bb.1.entry:
liveins: $w0
; Fold (0 % x) -> 0
;
; CHECK-LABEL: name: srem_0
; CHECK: liveins: $w0
; CHECK: %cst:_(s32) = G_CONSTANT i32 0
; CHECK: $w0 = COPY %cst(s32)
; CHECK: RET_ReallyLR implicit $w0
%x:_(s32) = COPY $w0
%cst:_(s32) = G_CONSTANT i32 0
%op:_(s32) = G_SREM %cst, %x
$w0 = COPY %op(s32)
RET_ReallyLR implicit $w0
...
---
name: urem_0
tracksRegLiveness: true
body: |
bb.1.entry:
liveins: $w0
; Fold (0 % x) -> 0
;
; CHECK-LABEL: name: urem_0
; CHECK: liveins: $w0
; CHECK: %cst:_(s32) = G_CONSTANT i32 0
; CHECK: $w0 = COPY %cst(s32)
; CHECK: RET_ReallyLR implicit $w0
%x:_(s32) = COPY $w0
%cst:_(s32) = G_CONSTANT i32 0
%op:_(s32) = G_UREM %cst, %x
$w0 = COPY %op(s32)
RET_ReallyLR implicit $w0
...
---
name: right_ident_or name: right_ident_or
tracksRegLiveness: true tracksRegLiveness: true
body: | body: |
bb.1.entry: bb.1.entry:
liveins: $w0 liveins: $w0
; Fold (x || 0) -> x ; Fold (x || 0) -> x
; ;
; CHECK-LABEL: name: right_ident_or ; CHECK-LABEL: name: right_ident_or
▲ Show 20 Lines • Show All 112 Lines • Show Last 20 Lines