maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[GlobalISel] Combine `undef / X -> 0` and `undef % X -> 0` 

This fixes the `urem_undef_lhs` case in the following:

https://gcc.godbolt.org/z/Wo9x7o679

Also see https://github.com/llvm/llvm-project/issues/57256 for more related
bugs.

This is equivalent to the undef bits in `simplifyDivRem` in the DAGCombiner.

Differential Revision: https://reviews.llvm.org/D135020
This commit is contained in:
Jessica Paquette 2022-10-01 13:36:39 -07:00
parent 3b0df701b0
commit 24553df57d
3 changed files with 95 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
llvm/include/llvm/Target/GlobalISel/Combine.td
View File

@ -231,7 +231,7 @@ def undef_to_negative_one: GICombineRule<
def binop_left_undef_to_zero: GICombineRule<
(defs root:$root),
(match (wip_match_opcode G_SHL):$root,
(match (wip_match_opcode G_SHL, G_UDIV, G_UREM):$root,
[{ return Helper.matchOperandIsUndef(*${root}, 1); }]),
(apply [{ Helper.replaceInstWithConstant(*${root}, 0); }])>;

94
llvm/test/CodeGen/AArch64/GlobalISel/combine-binop-undef-left-to-zero.mir Normal file
View File

@ -0,0 +1,94 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
# RUN: llc -o - -mtriple=aarch64-unknown-unknown -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs %s | FileCheck %s
---
name: test_combine_shl_undef_x_s32
body: |
bb.1:
liveins: $w0
; CHECK-LABEL: name: test_combine_shl_undef_x_s32
; CHECK: liveins: $w0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
; CHECK-NEXT: $w0 = COPY [[C]](s32)
%0:_(s32) = COPY $w0
%1:_(s32) = G_IMPLICIT_DEF
%2:_(s32) = G_SHL %1(s32), %0(s32)
$w0 = COPY %2(s32)
...
---
name: test_combine_shl_undef_x_v2s32
body: |
bb.1:
liveins: $d0
; CHECK-LABEL: name: test_combine_shl_undef_x_v2s32
; CHECK: liveins: $d0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
; CHECK-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s32>) = G_BUILD_VECTOR [[C]](s32), [[C]](s32)
; CHECK-NEXT: $d0 = COPY [[BUILD_VECTOR]](<2 x s32>)
%0:_(<2 x s32>) = COPY $d0
%1:_(<2 x s32>) = G_IMPLICIT_DEF
%2:_(<2 x s32>) = G_SHL %1(<2 x s32>), %0(<2 x s32>)
$d0 = COPY %2(<2 x s32>)
...
---
name: udiv_scalar
body: |
bb.1:
liveins: $w0
; CHECK-LABEL: name: udiv_scalar
; CHECK: liveins: $w0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: %op:_(s32) = G_CONSTANT i32 0
; CHECK-NEXT: $w0 = COPY %op(s32)
%rhs:_(s32) = COPY $w0
%undef:_(s32) = G_IMPLICIT_DEF
%op:_(s32) = G_UDIV %undef(s32), %rhs(s32)
$w0 = COPY %op(s32)
...
---
name: udiv_vector
body: |
bb.1:
liveins: $d0
; CHECK-LABEL: name: udiv_vector
; CHECK: liveins: $d0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
; CHECK-NEXT: %op:_(<2 x s32>) = G_BUILD_VECTOR [[C]](s32), [[C]](s32)
; CHECK-NEXT: $d0 = COPY %op(<2 x s32>)
%rhs:_(<2 x s32>) = COPY $d0
%undef:_(<2 x s32>) = G_IMPLICIT_DEF
%op:_(<2 x s32>) = G_UDIV %undef(<2 x s32>), %rhs(<2 x s32>)
$d0 = COPY %op(<2 x s32>)
...
---
name: urem_scalar
body: |
bb.1:
liveins: $w0
; CHECK-LABEL: name: urem_scalar
; CHECK: liveins: $w0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: %op:_(s32) = G_CONSTANT i32 0
; CHECK-NEXT: $w0 = COPY %op(s32)
%rhs:_(s32) = COPY $w0
%undef:_(s32) = G_IMPLICIT_DEF
%op:_(s32) = G_UREM %undef(s32), %rhs(s32)
$w0 = COPY %op(s32)
...
---
name: urem_vector
body: |
bb.1:
liveins: $d0
; CHECK-LABEL: name: urem_vector
; CHECK: liveins: $d0
; CHECK-NEXT: {{ $}}
; CHECK-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
; CHECK-NEXT: %op:_(<2 x s32>) = G_BUILD_VECTOR [[C]](s32), [[C]](s32)
; CHECK-NEXT: $d0 = COPY %op(<2 x s32>)
%rhs:_(<2 x s32>) = COPY $d0
%undef:_(<2 x s32>) = G_IMPLICIT_DEF
%op:_(<2 x s32>) = G_UREM %undef(<2 x s32>), %rhs(<2 x s32>)
$d0 = COPY %op(<2 x s32>)

29
llvm/test/CodeGen/AArch64/GlobalISel/combine-shl.mir
View File

@ -1,29 +0,0 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
# RUN: llc -o - -mtriple=aarch64-unknown-unknown -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs %s | FileCheck %s
---
name: test_combine_shl_undef_x_s32
body: |
bb.1:
liveins: $w0
; CHECK-LABEL: name: test_combine_shl_undef_x_s32
; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
; CHECK: $w0 = COPY [[C]](s32)
%0:_(s32) = COPY $w0
%1:_(s32) = G_IMPLICIT_DEF
%2:_(s32) = G_SHL %1(s32), %0(s32)
$w0 = COPY %2(s32)
...
---
name: test_combine_shl_undef_x_v2s32
body: |
bb.1:
liveins: $d0
; CHECK-LABEL: name: test_combine_shl_undef_x_v2s32
; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
; CHECK: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s32>) = G_BUILD_VECTOR [[C]](s32), [[C]](s32)
; CHECK: $d0 = COPY [[BUILD_VECTOR]](<2 x s32>)
%0:_(<2 x s32>) = COPY $d0
%1:_(<2 x s32>) = G_IMPLICIT_DEF
%2:_(<2 x s32>) = G_SHL %1(<2 x s32>), %0(<2 x s32>)
$d0 = COPY %2(<2 x s32>)
...