[llvm] 4d815bf - [GISel] Add redundant bitcast folding combine
Pierre van Houtryve via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 11 08:03:17 PDT 2022
Author: Pierre van Houtryve
Date: 2022-10-11T15:03:08Z
New Revision: 4d815bfae0ea556629756aea7ad8d1520131f9ff
URL: https://github.com/llvm/llvm-project/commit/4d815bfae0ea556629756aea7ad8d1520131f9ff
DIFF: https://github.com/llvm/llvm-project/commit/4d815bfae0ea556629756aea7ad8d1520131f9ff.diff
LOG: [GISel] Add redundant bitcast folding combine
Simply folds away bitcasts that cancel each other.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D135146
Added:
llvm/test/CodeGen/AMDGPU/GlobalISel/prelegalizer-combiner-redundant-bitcast.mir
Modified:
llvm/include/llvm/Target/GlobalISel/Combine.td
Removed:
################################################################################
diff --git a/llvm/include/llvm/Target/GlobalISel/Combine.td b/llvm/include/llvm/Target/GlobalISel/Combine.td
index 702e9f72e325c..2d61315924006 100644
--- a/llvm/include/llvm/Target/GlobalISel/Combine.td
+++ b/llvm/include/llvm/Target/GlobalISel/Combine.td
@@ -967,6 +967,12 @@ def sub_add_reg: GICombineRule <
[{ return Helper.matchSubAddSameReg(*${root}, ${matchinfo}); }]),
(apply [{ Helper.applyBuildFn(*${root}, ${matchinfo}); }])>;
+def bitcast_bitcast_fold : GICombineRule<
+ (defs root:$dst),
+ (match (G_BITCAST $dst, $src1):$op, (G_BITCAST $src1, $src0),
+ [{ return MRI.getType(${src0}.getReg()) == MRI.getType(${dst}.getReg()); }]),
+ (apply [{ Helper.replaceSingleDefInstWithReg(*${op}, ${src0}.getReg()); }])>;
+
def select_to_minmax: GICombineRule<
(defs root:$root, build_fn_matchinfo:$info),
(match (wip_match_opcode G_SELECT):$root,
@@ -993,7 +999,8 @@ def identity_combines : GICombineGroup<[select_same_val, right_identity_zero,
fneg_fneg_fold, right_identity_one,
add_sub_reg, buildvector_identity_fold,
trunc_buildvector_fold,
- trunc_lshr_buildvector_fold]>;
+ trunc_lshr_buildvector_fold,
+ bitcast_bitcast_fold]>;
def const_combines : GICombineGroup<[constant_fp_op, const_ptradd_to_i2p,
overlapping_and, mulo_by_2, mulo_by_0,
diff --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/prelegalizer-combiner-redundant-bitcast.mir b/llvm/test/CodeGen/AMDGPU/GlobalISel/prelegalizer-combiner-redundant-bitcast.mir
new file mode 100644
index 0000000000000..6371001c40764
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/prelegalizer-combiner-redundant-bitcast.mir
@@ -0,0 +1,55 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -run-pass=amdgpu-prelegalizer-combiner -verify-machineinstrs -o - %s | FileCheck %s
+
+---
+name: s32_bitcast
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $vgpr0
+ ; CHECK-LABEL: name: s32_bitcast
+ ; CHECK: liveins: $vgpr0
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: %src:_(<2 x s16>) = COPY $vgpr0
+ ; CHECK-NEXT: $vgpr0 = COPY %src(<2 x s16>)
+ %src:_(<2 x s16>) = COPY $vgpr0
+ %b1:_(s32) = G_BITCAST %src
+ %b2:_(<2 x s16>) = G_BITCAST %b1
+ $vgpr0 = COPY %b2
+...
+
+---
+name: s64_bitcast
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $vgpr0_vgpr1
+ ; CHECK-LABEL: name: s64_bitcast
+ ; CHECK: liveins: $vgpr0_vgpr1
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: %src:_(<2 x s32>) = COPY $vgpr0_vgpr1
+ ; CHECK-NEXT: $vgpr0_vgpr1 = COPY %src(<2 x s32>)
+ %src:_(<2 x s32>) = COPY $vgpr0_vgpr1
+ %b1:_(s64) = G_BITCAST %src
+ %b2:_(<2 x s32>) = G_BITCAST %b1
+ $vgpr0_vgpr1 = COPY %b2
+...
+
+---
+name: s64_bitcast_
diff erentypes_nofold
+tracksRegLiveness: true
+body: |
+ bb.0:
+ liveins: $vgpr0_vgpr1
+ ; CHECK-LABEL: name: s64_bitcast_
diff erentypes_nofold
+ ; CHECK: liveins: $vgpr0_vgpr1
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: %src:_(<2 x s32>) = COPY $vgpr0_vgpr1
+ ; CHECK-NEXT: %b1:_(s64) = G_BITCAST %src(<2 x s32>)
+ ; CHECK-NEXT: %b2:_(<4 x s16>) = G_BITCAST %b1(s64)
+ ; CHECK-NEXT: $vgpr0_vgpr1 = COPY %b2(<4 x s16>)
+ %src:_(<2 x s32>) = COPY $vgpr0_vgpr1
+ %b1:_(s64) = G_BITCAST %src
+ %b2:_(<4 x s16>) = G_BITCAST %b1
+ $vgpr0_vgpr1 = COPY %b2
+...
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