[llvm] [AMDGPU] Canonicalize G_ZEXT of the shift amount in RegBankCombiner (PR #131792)

Pierre van Houtryve via llvm-commits llvm-commits at lists.llvm.org
Wed Mar 26 02:48:26 PDT 2025


https://github.com/Pierre-vh updated https://github.com/llvm/llvm-project/pull/131792

>From 79951fae5d5d71149523d2539bbfb036a9b941f9 Mon Sep 17 00:00:00 2001
From: pvanhout <pierre.vanhoutryve at amd.com>
Date: Mon, 17 Mar 2025 15:29:37 +0100
Subject: [PATCH 1/2] [AMDGPU] Canonicalize G_ZEXT of the shift amount in
 RegBankCombiner

Canonicalize it to a G_AND instead so that ISel patterns can pick it
up and ignore it, as the shift instructions only read low bits.
G_ZEXT would be lowered to a v/s_and anyway in most cases.
---
 llvm/lib/Target/AMDGPU/AMDGPUCombine.td       |  18 ++-
 .../Target/AMDGPU/AMDGPURegBankCombiner.cpp   |  30 ++++
 .../GlobalISel/combine-shift-amount-zext.mir  | 146 ++++++++++++++++++
 3 files changed, 193 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/AMDGPU/GlobalISel/combine-shift-amount-zext.mir

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUCombine.td b/llvm/lib/Target/AMDGPU/AMDGPUCombine.td
index a21505356274b..a0eb0ffea8d7e 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUCombine.td
+++ b/llvm/lib/Target/AMDGPU/AMDGPUCombine.td
@@ -134,6 +134,22 @@ def combine_fmul_with_select_to_fldexp : GICombineRule<
           [{ return Helper.matchCombineFmulWithSelectToFldexp(*${root}, *${sel}, ${matchinfo}); }]),
   (apply  [{ Helper.applyBuildFn(*${root}, ${matchinfo}); }])>;
 
+// (shift x, (zext amt)) -> (shift x, (and (anyext amt), mask)
+//
+// The pattern is longer, but is better for matching during ISel.
+class canonicalize_zext_shift_amt<Instruction opc> : GICombineRule<
+  (defs root:$dst),
+  (match  (G_ZEXT $amt, $amtsrc):$zext,
+          (opc $dst, $src, $amt):$shift),
+  (apply  [{ applyCanonicalizeZextShiftAmt(*${shift}, *${zext}); }])>;
+
+def canonicalize_zext_lshr : canonicalize_zext_shift_amt<G_LSHR>;
+def canonicalize_zext_ashr : canonicalize_zext_shift_amt<G_ASHR>;
+def canonicalize_zext_shl : canonicalize_zext_shift_amt<G_SHL>;
+
+def zext_of_shift_amount_combines : GICombineGroup<[
+  canonicalize_zext_lshr, canonicalize_zext_ashr, canonicalize_zext_shl
+]>;
 
 let Predicates = [Has16BitInsts, NotHasMed3_16] in {
 // For gfx8, expand f16-fmed3-as-f32 into a min/max f16 sequence. This
@@ -181,5 +197,5 @@ def AMDGPURegBankCombiner : GICombiner<
    zext_trunc_fold, int_minmax_to_med3, ptr_add_immed_chain,
    fp_minmax_to_clamp, fp_minmax_to_med3, fmed3_intrinsic_to_clamp,
    identity_combines, redundant_and, constant_fold_cast_op,
-   cast_of_cast_combines]> {
+   cast_of_cast_combines, zext_of_shift_amount_combines]> {
 }
diff --git a/llvm/lib/Target/AMDGPU/AMDGPURegBankCombiner.cpp b/llvm/lib/Target/AMDGPU/AMDGPURegBankCombiner.cpp
index 98c48f4fe3705..68bffe5bbb7f5 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPURegBankCombiner.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPURegBankCombiner.cpp
@@ -87,6 +87,8 @@ class AMDGPURegBankCombinerImpl : public Combiner {
   void applyMed3(MachineInstr &MI, Med3MatchInfo &MatchInfo) const;
   void applyClamp(MachineInstr &MI, Register &Reg) const;
 
+  void applyCanonicalizeZextShiftAmt(MachineInstr &MI, MachineInstr &Ext) const;
+
 private:
   SIModeRegisterDefaults getMode() const;
   bool getIEEE() const;
@@ -362,6 +364,34 @@ void AMDGPURegBankCombinerImpl::applyMed3(MachineInstr &MI,
   MI.eraseFromParent();
 }
 
+void AMDGPURegBankCombinerImpl::applyCanonicalizeZextShiftAmt(
+    MachineInstr &MI, MachineInstr &Ext) const {
+  unsigned ShOpc = MI.getOpcode();
+  assert(ShOpc == AMDGPU::G_SHL || ShOpc == AMDGPU::G_LSHR ||
+         ShOpc == AMDGPU::G_ASHR);
+  assert(Ext.getOpcode() == AMDGPU::G_ZEXT);
+
+  Register AmtReg = Ext.getOperand(1).getReg();
+  Register ShDst = MI.getOperand(0).getReg();
+  Register ShSrc = MI.getOperand(1).getReg();
+
+  LLT ExtAmtTy = MRI.getType(Ext.getOperand(0).getReg());
+  LLT AmtTy = MRI.getType(AmtReg);
+
+  auto &RB = *MRI.getRegBank(AmtReg);
+
+  auto NewExt = B.buildAnyExt(ExtAmtTy, AmtReg);
+  auto Mask = B.buildConstant(
+      ExtAmtTy, maskTrailingOnes<uint64_t>(AmtTy.getScalarSizeInBits()));
+  auto And = B.buildAnd(ExtAmtTy, NewExt, Mask);
+  B.buildInstr(ShOpc, {ShDst}, {ShSrc, And});
+
+  MRI.setRegBank(NewExt.getReg(0), RB);
+  MRI.setRegBank(Mask.getReg(0), RB);
+  MRI.setRegBank(And.getReg(0), RB);
+  MI.eraseFromParent();
+}
+
 SIModeRegisterDefaults AMDGPURegBankCombinerImpl::getMode() const {
   return MF.getInfo<SIMachineFunctionInfo>()->getMode();
 }
diff --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/combine-shift-amount-zext.mir b/llvm/test/CodeGen/AMDGPU/GlobalISel/combine-shift-amount-zext.mir
new file mode 100644
index 0000000000000..77d30f6fa5223
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/combine-shift-amount-zext.mir
@@ -0,0 +1,146 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn -run-pass=amdgpu-regbank-combiner %s -o - | FileCheck %s
+
+---
+name:            lshr_zext_i16
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $sgpr0, $sgpr1
+
+    ; CHECK-LABEL: name: lshr_zext_i16
+    ; CHECK: liveins: $sgpr0, $sgpr1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %src:sgpr(s32) = COPY $sgpr0
+    ; CHECK-NEXT: %regamt:sgpr(s32) = COPY $sgpr1
+    ; CHECK-NEXT: [[C:%[0-9]+]]:sgpr(s32) = G_CONSTANT i32 65535
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:sgpr(s32) = G_AND %regamt, [[C]]
+    ; CHECK-NEXT: %res:sgpr(s32) = G_LSHR %src, [[AND]](s32)
+    ; CHECK-NEXT: $sgpr0 = COPY %res(s32)
+    %src:sgpr(s32) = COPY $sgpr0
+    %regamt:sgpr(s32) = COPY $sgpr1
+    %amt:sgpr(s16) = G_TRUNC %regamt
+    %zextamt:sgpr(s32) = G_ZEXT %amt
+    %res:sgpr(s32) = G_LSHR %src, %zextamt
+    $sgpr0 = COPY %res
+...
+
+---
+name:            ashr_zext_i16
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $sgpr0, $sgpr1
+
+    ; CHECK-LABEL: name: ashr_zext_i16
+    ; CHECK: liveins: $sgpr0, $sgpr1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %src:sgpr(s32) = COPY $sgpr0
+    ; CHECK-NEXT: %regamt:sgpr(s32) = COPY $sgpr1
+    ; CHECK-NEXT: [[C:%[0-9]+]]:sgpr(s32) = G_CONSTANT i32 65535
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:sgpr(s32) = G_AND %regamt, [[C]]
+    ; CHECK-NEXT: %res:sgpr(s32) = G_ASHR %src, [[AND]](s32)
+    ; CHECK-NEXT: $sgpr0 = COPY %res(s32)
+    %src:sgpr(s32) = COPY $sgpr0
+    %regamt:sgpr(s32) = COPY $sgpr1
+    %amt:sgpr(s16) = G_TRUNC %regamt
+    %zextamt:sgpr(s32) = G_ZEXT %amt
+    %res:sgpr(s32) = G_ASHR %src, %zextamt
+    $sgpr0 = COPY %res
+...
+
+---
+name:            shl_zext_i16
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $sgpr0, $sgpr1
+
+    ; CHECK-LABEL: name: shl_zext_i16
+    ; CHECK: liveins: $sgpr0, $sgpr1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %src:sgpr(s32) = COPY $sgpr0
+    ; CHECK-NEXT: %regamt:sgpr(s32) = COPY $sgpr1
+    ; CHECK-NEXT: [[C:%[0-9]+]]:sgpr(s32) = G_CONSTANT i32 65535
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:sgpr(s32) = G_AND %regamt, [[C]]
+    ; CHECK-NEXT: %res:sgpr(s32) = G_SHL %src, [[AND]](s32)
+    ; CHECK-NEXT: $sgpr0 = COPY %res(s32)
+    %src:sgpr(s32) = COPY $sgpr0
+    %regamt:sgpr(s32) = COPY $sgpr1
+    %amt:sgpr(s16) = G_TRUNC %regamt
+    %zextamt:sgpr(s32) = G_ZEXT %amt
+    %res:sgpr(s32) = G_SHL %src, %zextamt
+    $sgpr0 = COPY %res
+...
+
+---
+name:            lshr_zext_i8
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $sgpr0, $sgpr1
+
+    ; CHECK-LABEL: name: lshr_zext_i8
+    ; CHECK: liveins: $sgpr0, $sgpr1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %src:sgpr(s32) = COPY $sgpr0
+    ; CHECK-NEXT: %regamt:sgpr(s32) = COPY $sgpr1
+    ; CHECK-NEXT: [[C:%[0-9]+]]:sgpr(s32) = G_CONSTANT i32 255
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:sgpr(s32) = G_AND %regamt, [[C]]
+    ; CHECK-NEXT: %res:sgpr(s32) = G_LSHR %src, [[AND]](s32)
+    ; CHECK-NEXT: $sgpr0 = COPY %res(s32)
+    %src:sgpr(s32) = COPY $sgpr0
+    %regamt:sgpr(s32) = COPY $sgpr1
+    %amt:sgpr(s8) = G_TRUNC %regamt
+    %zextamt:sgpr(s32) = G_ZEXT %amt
+    %res:sgpr(s32) = G_LSHR %src, %zextamt
+    $sgpr0 = COPY %res
+...
+
+---
+name:            ashr_zext_i8
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $sgpr0, $sgpr1
+
+    ; CHECK-LABEL: name: ashr_zext_i8
+    ; CHECK: liveins: $sgpr0, $sgpr1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %src:sgpr(s32) = COPY $sgpr0
+    ; CHECK-NEXT: %regamt:sgpr(s32) = COPY $sgpr1
+    ; CHECK-NEXT: [[C:%[0-9]+]]:sgpr(s32) = G_CONSTANT i32 255
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:sgpr(s32) = G_AND %regamt, [[C]]
+    ; CHECK-NEXT: %res:sgpr(s32) = G_ASHR %src, [[AND]](s32)
+    ; CHECK-NEXT: $sgpr0 = COPY %res(s32)
+    %src:sgpr(s32) = COPY $sgpr0
+    %regamt:sgpr(s32) = COPY $sgpr1
+    %amt:sgpr(s8) = G_TRUNC %regamt
+    %zextamt:sgpr(s32) = G_ZEXT %amt
+    %res:sgpr(s32) = G_ASHR %src, %zextamt
+    $sgpr0 = COPY %res
+...
+
+---
+name:            shl_zext_i8
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $sgpr0, $sgpr1
+
+    ; CHECK-LABEL: name: shl_zext_i8
+    ; CHECK: liveins: $sgpr0, $sgpr1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %src:sgpr(s32) = COPY $sgpr0
+    ; CHECK-NEXT: %regamt:sgpr(s32) = COPY $sgpr1
+    ; CHECK-NEXT: [[C:%[0-9]+]]:sgpr(s32) = G_CONSTANT i32 255
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:sgpr(s32) = G_AND %regamt, [[C]]
+    ; CHECK-NEXT: %res:sgpr(s32) = G_SHL %src, [[AND]](s32)
+    ; CHECK-NEXT: $sgpr0 = COPY %res(s32)
+    %src:sgpr(s32) = COPY $sgpr0
+    %regamt:sgpr(s32) = COPY $sgpr1
+    %amt:sgpr(s8) = G_TRUNC %regamt
+    %zextamt:sgpr(s32) = G_ZEXT %amt
+    %res:sgpr(s32) = G_SHL %src, %zextamt
+    $sgpr0 = COPY %res
+...

>From a71242df8f384cf87a00754707a3657694bec09c Mon Sep 17 00:00:00 2001
From: pvanhout <pierre.vanhoutryve at amd.com>
Date: Wed, 26 Mar 2025 10:39:01 +0100
Subject: [PATCH 2/2] update tests

---
 llvm/test/CodeGen/AMDGPU/GlobalISel/fshl.ll | 32 +---------
 llvm/test/CodeGen/AMDGPU/GlobalISel/fshr.ll | 66 +++++++--------------
 2 files changed, 23 insertions(+), 75 deletions(-)

diff --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/fshl.ll b/llvm/test/CodeGen/AMDGPU/GlobalISel/fshl.ll
index 07fcb02d98649..18019fa31410e 100644
--- a/llvm/test/CodeGen/AMDGPU/GlobalISel/fshl.ll
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/fshl.ll
@@ -3329,9 +3329,7 @@ define i16 @v_fshl_i16(i16 %lhs, i16 %rhs, i16 %amt) {
 ; GFX6-NEXT:    v_and_b32_e32 v3, 15, v2
 ; GFX6-NEXT:    v_xor_b32_e32 v2, -1, v2
 ; GFX6-NEXT:    v_and_b32_e32 v2, 15, v2
-; GFX6-NEXT:    v_and_b32_e32 v3, 0xffff, v3
 ; GFX6-NEXT:    v_bfe_u32 v1, v1, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v2, 0xffff, v2
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v0, v3, v0
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v1, v2, v1
 ; GFX6-NEXT:    v_or_b32_e32 v0, v0, v1
@@ -3486,10 +3484,8 @@ define amdgpu_ps half @v_fshl_i16_ssv(i16 inreg %lhs, i16 inreg %rhs, i16 %amt)
 ; GFX6-NEXT:    v_and_b32_e32 v1, 15, v0
 ; GFX6-NEXT:    v_xor_b32_e32 v0, -1, v0
 ; GFX6-NEXT:    v_and_b32_e32 v0, 15, v0
-; GFX6-NEXT:    v_and_b32_e32 v1, 0xffff, v1
 ; GFX6-NEXT:    v_lshl_b32_e32 v1, s0, v1
 ; GFX6-NEXT:    s_bfe_u32 s0, s1, 0xf0001
-; GFX6-NEXT:    v_and_b32_e32 v0, 0xffff, v0
 ; GFX6-NEXT:    v_lshr_b32_e32 v0, s0, v0
 ; GFX6-NEXT:    v_or_b32_e32 v0, v1, v0
 ; GFX6-NEXT:    ; return to shader part epilog
@@ -3793,20 +3789,16 @@ define <2 x i16> @v_fshl_v2i16(<2 x i16> %lhs, <2 x i16> %rhs, <2 x i16> %amt) {
 ; GFX6-NEXT:    v_and_b32_e32 v6, 15, v4
 ; GFX6-NEXT:    v_xor_b32_e32 v4, -1, v4
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v4
-; GFX6-NEXT:    v_and_b32_e32 v6, 0xffff, v6
 ; GFX6-NEXT:    v_bfe_u32 v2, v2, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v4
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v0, v6, v0
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v2, v4, v2
 ; GFX6-NEXT:    v_or_b32_e32 v0, v0, v2
 ; GFX6-NEXT:    v_and_b32_e32 v2, 15, v5
 ; GFX6-NEXT:    v_xor_b32_e32 v4, -1, v5
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v4
-; GFX6-NEXT:    v_and_b32_e32 v2, 0xffff, v2
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v1, v2, v1
 ; GFX6-NEXT:    v_bfe_u32 v2, v3, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v3, 0xffff, v4
-; GFX6-NEXT:    v_lshrrev_b32_e32 v2, v3, v2
+; GFX6-NEXT:    v_lshrrev_b32_e32 v2, v4, v2
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v2
 ; GFX6-NEXT:    s_setpc_b64 s[30:31]
 ;
@@ -3942,18 +3934,14 @@ define amdgpu_ps float @v_fshl_v2i16_ssv(<2 x i16> inreg %lhs, <2 x i16> inreg %
 ; GFX6-NEXT:    v_and_b32_e32 v2, 15, v0
 ; GFX6-NEXT:    v_xor_b32_e32 v0, -1, v0
 ; GFX6-NEXT:    v_and_b32_e32 v0, 15, v0
-; GFX6-NEXT:    v_and_b32_e32 v2, 0xffff, v2
 ; GFX6-NEXT:    v_lshl_b32_e32 v2, s0, v2
 ; GFX6-NEXT:    s_bfe_u32 s0, s2, 0xf0001
-; GFX6-NEXT:    v_and_b32_e32 v0, 0xffff, v0
 ; GFX6-NEXT:    v_lshr_b32_e32 v0, s0, v0
 ; GFX6-NEXT:    v_or_b32_e32 v0, v2, v0
 ; GFX6-NEXT:    v_and_b32_e32 v2, 15, v1
 ; GFX6-NEXT:    v_xor_b32_e32 v1, -1, v1
 ; GFX6-NEXT:    v_and_b32_e32 v1, 15, v1
-; GFX6-NEXT:    v_and_b32_e32 v2, 0xffff, v2
 ; GFX6-NEXT:    s_bfe_u32 s0, s3, 0xf0001
-; GFX6-NEXT:    v_and_b32_e32 v1, 0xffff, v1
 ; GFX6-NEXT:    v_lshl_b32_e32 v2, s1, v2
 ; GFX6-NEXT:    v_lshr_b32_e32 v1, s0, v1
 ; GFX6-NEXT:    v_or_b32_e32 v1, v2, v1
@@ -4450,28 +4438,22 @@ define <3 x half> @v_fshl_v3i16(<3 x i16> %lhs, <3 x i16> %rhs, <3 x i16> %amt)
 ; GFX6-NEXT:    v_and_b32_e32 v9, 15, v6
 ; GFX6-NEXT:    v_xor_b32_e32 v6, -1, v6
 ; GFX6-NEXT:    v_and_b32_e32 v6, 15, v6
-; GFX6-NEXT:    v_and_b32_e32 v9, 0xffff, v9
 ; GFX6-NEXT:    v_bfe_u32 v3, v3, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v6, 0xffff, v6
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v0, v9, v0
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v3, v6, v3
 ; GFX6-NEXT:    v_or_b32_e32 v0, v0, v3
 ; GFX6-NEXT:    v_and_b32_e32 v3, 15, v7
 ; GFX6-NEXT:    v_xor_b32_e32 v6, -1, v7
 ; GFX6-NEXT:    v_and_b32_e32 v6, 15, v6
-; GFX6-NEXT:    v_and_b32_e32 v3, 0xffff, v3
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v1, v3, v1
 ; GFX6-NEXT:    v_bfe_u32 v3, v4, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v6
-; GFX6-NEXT:    v_lshrrev_b32_e32 v3, v4, v3
+; GFX6-NEXT:    v_lshrrev_b32_e32 v3, v6, v3
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v3
 ; GFX6-NEXT:    v_and_b32_e32 v3, 15, v8
 ; GFX6-NEXT:    v_xor_b32_e32 v4, -1, v8
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v4
-; GFX6-NEXT:    v_and_b32_e32 v3, 0xffff, v3
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v2, v3, v2
 ; GFX6-NEXT:    v_bfe_u32 v3, v5, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v4
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v3, v4, v3
 ; GFX6-NEXT:    v_or_b32_e32 v2, v2, v3
 ; GFX6-NEXT:    s_setpc_b64 s[30:31]
@@ -4790,37 +4772,29 @@ define <4 x half> @v_fshl_v4i16(<4 x i16> %lhs, <4 x i16> %rhs, <4 x i16> %amt)
 ; GFX6-NEXT:    v_and_b32_e32 v12, 15, v8
 ; GFX6-NEXT:    v_xor_b32_e32 v8, -1, v8
 ; GFX6-NEXT:    v_and_b32_e32 v8, 15, v8
-; GFX6-NEXT:    v_and_b32_e32 v12, 0xffff, v12
 ; GFX6-NEXT:    v_bfe_u32 v4, v4, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v8, 0xffff, v8
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v0, v12, v0
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v8, v4
 ; GFX6-NEXT:    v_or_b32_e32 v0, v0, v4
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v9
 ; GFX6-NEXT:    v_xor_b32_e32 v8, -1, v9
 ; GFX6-NEXT:    v_and_b32_e32 v8, 15, v8
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v4
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v1, v4, v1
 ; GFX6-NEXT:    v_bfe_u32 v4, v5, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v5, 0xffff, v8
-; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v5, v4
+; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v8, v4
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v4
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v10
 ; GFX6-NEXT:    v_xor_b32_e32 v5, -1, v10
 ; GFX6-NEXT:    v_and_b32_e32 v5, 15, v5
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v4
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v2, v4, v2
 ; GFX6-NEXT:    v_bfe_u32 v4, v6, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v5, 0xffff, v5
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v5, v4
 ; GFX6-NEXT:    v_or_b32_e32 v2, v2, v4
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v11
 ; GFX6-NEXT:    v_xor_b32_e32 v5, -1, v11
 ; GFX6-NEXT:    v_and_b32_e32 v5, 15, v5
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v4
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v3, v4, v3
 ; GFX6-NEXT:    v_bfe_u32 v4, v7, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v5, 0xffff, v5
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v5, v4
 ; GFX6-NEXT:    v_or_b32_e32 v3, v3, v4
 ; GFX6-NEXT:    s_setpc_b64 s[30:31]
diff --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/fshr.ll b/llvm/test/CodeGen/AMDGPU/GlobalISel/fshr.ll
index 2e8c918e4c67e..d441a9a62fc1c 100644
--- a/llvm/test/CodeGen/AMDGPU/GlobalISel/fshr.ll
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/fshr.ll
@@ -3077,11 +3077,9 @@ define i16 @v_fshr_i16(i16 %lhs, i16 %rhs, i16 %amt) {
 ; GFX6-NEXT:    v_xor_b32_e32 v2, -1, v2
 ; GFX6-NEXT:    v_and_b32_e32 v2, 15, v2
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v0, 1, v0
-; GFX6-NEXT:    v_and_b32_e32 v2, 0xffff, v2
-; GFX6-NEXT:    v_lshlrev_b32_e32 v0, v2, v0
-; GFX6-NEXT:    v_and_b32_e32 v2, 0xffff, v3
 ; GFX6-NEXT:    v_and_b32_e32 v1, 0xffff, v1
-; GFX6-NEXT:    v_lshrrev_b32_e32 v1, v2, v1
+; GFX6-NEXT:    v_lshlrev_b32_e32 v0, v2, v0
+; GFX6-NEXT:    v_lshrrev_b32_e32 v1, v3, v1
 ; GFX6-NEXT:    v_or_b32_e32 v0, v0, v1
 ; GFX6-NEXT:    s_setpc_b64 s[30:31]
 ;
@@ -3235,9 +3233,7 @@ define amdgpu_ps half @v_fshr_i16_ssv(i16 inreg %lhs, i16 inreg %rhs, i16 %amt)
 ; GFX6-NEXT:    v_xor_b32_e32 v0, -1, v0
 ; GFX6-NEXT:    v_and_b32_e32 v0, 15, v0
 ; GFX6-NEXT:    s_lshl_b32 s0, s0, 1
-; GFX6-NEXT:    v_and_b32_e32 v0, 0xffff, v0
 ; GFX6-NEXT:    v_lshl_b32_e32 v0, s0, v0
-; GFX6-NEXT:    v_and_b32_e32 v1, 0xffff, v1
 ; GFX6-NEXT:    s_and_b32 s0, s1, 0xffff
 ; GFX6-NEXT:    v_lshr_b32_e32 v1, s0, v1
 ; GFX6-NEXT:    v_or_b32_e32 v0, v0, v1
@@ -3570,26 +3566,22 @@ define <2 x i16> @v_fshr_v2i16(<2 x i16> %lhs, <2 x i16> %rhs, <2 x i16> %amt) {
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v5, 14, v5
 ; GFX6-NEXT:    v_xor_b32_e32 v4, -1, v4
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v5
+; GFX6-NEXT:    v_lshlrev_b32_e32 v2, 1, v2
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v5, 16, v4
 ; GFX6-NEXT:    v_and_b32_e32 v6, 15, v4
 ; GFX6-NEXT:    v_xor_b32_e32 v4, -1, v4
-; GFX6-NEXT:    v_lshlrev_b32_e32 v2, 1, v2
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v4
-; GFX6-NEXT:    v_and_b32_e32 v6, 0xffff, v6
 ; GFX6-NEXT:    v_bfe_u32 v2, v2, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v4
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v0, v6, v0
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v2, v4, v2
+; GFX6-NEXT:    v_lshlrev_b32_e32 v3, 1, v3
 ; GFX6-NEXT:    v_or_b32_e32 v0, v0, v2
 ; GFX6-NEXT:    v_and_b32_e32 v2, 15, v5
 ; GFX6-NEXT:    v_xor_b32_e32 v4, -1, v5
-; GFX6-NEXT:    v_lshlrev_b32_e32 v3, 1, v3
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v4
-; GFX6-NEXT:    v_and_b32_e32 v2, 0xffff, v2
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v1, v2, v1
 ; GFX6-NEXT:    v_bfe_u32 v2, v3, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v3, 0xffff, v4
-; GFX6-NEXT:    v_lshrrev_b32_e32 v2, v3, v2
+; GFX6-NEXT:    v_lshrrev_b32_e32 v2, v4, v2
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v2
 ; GFX6-NEXT:    s_setpc_b64 s[30:31]
 ;
@@ -3735,32 +3727,28 @@ define amdgpu_ps float @v_fshr_v2i16_ssv(<2 x i16> inreg %lhs, <2 x i16> inreg %
 ; GFX6-NEXT:    v_and_b32_e32 v0, 0xffff, v0
 ; GFX6-NEXT:    v_or_b32_e32 v0, v1, v0
 ; GFX6-NEXT:    s_bfe_u32 s4, s2, 0xf0001
-; GFX6-NEXT:    v_xor_b32_e32 v0, -1, v0
 ; GFX6-NEXT:    s_lshl_b32 s0, s0, 1
 ; GFX6-NEXT:    s_lshr_b32 s4, s4, 14
-; GFX6-NEXT:    v_lshrrev_b32_e32 v1, 16, v0
-; GFX6-NEXT:    v_and_b32_e32 v2, 15, v0
 ; GFX6-NEXT:    v_xor_b32_e32 v0, -1, v0
 ; GFX6-NEXT:    s_or_b32 s0, s0, s4
 ; GFX6-NEXT:    s_lshl_b32 s2, s2, 1
+; GFX6-NEXT:    v_lshrrev_b32_e32 v1, 16, v0
+; GFX6-NEXT:    v_and_b32_e32 v2, 15, v0
+; GFX6-NEXT:    v_xor_b32_e32 v0, -1, v0
 ; GFX6-NEXT:    v_and_b32_e32 v0, 15, v0
-; GFX6-NEXT:    v_and_b32_e32 v2, 0xffff, v2
 ; GFX6-NEXT:    v_lshl_b32_e32 v2, s0, v2
 ; GFX6-NEXT:    s_bfe_u32 s0, s2, 0xf0001
-; GFX6-NEXT:    v_and_b32_e32 v0, 0xffff, v0
-; GFX6-NEXT:    v_lshr_b32_e32 v0, s0, v0
 ; GFX6-NEXT:    s_bfe_u32 s4, s3, 0xf0001
-; GFX6-NEXT:    v_or_b32_e32 v0, v2, v0
-; GFX6-NEXT:    v_and_b32_e32 v2, 15, v1
-; GFX6-NEXT:    v_xor_b32_e32 v1, -1, v1
+; GFX6-NEXT:    v_lshr_b32_e32 v0, s0, v0
 ; GFX6-NEXT:    s_lshl_b32 s1, s1, 1
 ; GFX6-NEXT:    s_lshr_b32 s4, s4, 14
 ; GFX6-NEXT:    s_lshl_b32 s3, s3, 1
-; GFX6-NEXT:    v_and_b32_e32 v1, 15, v1
+; GFX6-NEXT:    v_or_b32_e32 v0, v2, v0
+; GFX6-NEXT:    v_and_b32_e32 v2, 15, v1
+; GFX6-NEXT:    v_xor_b32_e32 v1, -1, v1
 ; GFX6-NEXT:    s_or_b32 s1, s1, s4
-; GFX6-NEXT:    v_and_b32_e32 v2, 0xffff, v2
+; GFX6-NEXT:    v_and_b32_e32 v1, 15, v1
 ; GFX6-NEXT:    s_bfe_u32 s0, s3, 0xf0001
-; GFX6-NEXT:    v_and_b32_e32 v1, 0xffff, v1
 ; GFX6-NEXT:    v_lshl_b32_e32 v2, s1, v2
 ; GFX6-NEXT:    v_lshr_b32_e32 v1, s0, v1
 ; GFX6-NEXT:    v_or_b32_e32 v1, v2, v1
@@ -4358,26 +4346,22 @@ define <3 x half> @v_fshr_v3i16(<3 x i16> %lhs, <3 x i16> %rhs, <3 x i16> %amt)
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v8, 14, v8
 ; GFX6-NEXT:    v_xor_b32_e32 v6, -1, v6
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v8
+; GFX6-NEXT:    v_lshlrev_b32_e32 v3, 1, v3
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v8, 16, v6
 ; GFX6-NEXT:    v_and_b32_e32 v9, 15, v6
 ; GFX6-NEXT:    v_xor_b32_e32 v6, -1, v6
-; GFX6-NEXT:    v_lshlrev_b32_e32 v3, 1, v3
 ; GFX6-NEXT:    v_and_b32_e32 v6, 15, v6
-; GFX6-NEXT:    v_and_b32_e32 v9, 0xffff, v9
 ; GFX6-NEXT:    v_bfe_u32 v3, v3, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v6, 0xffff, v6
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v0, v9, v0
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v3, v6, v3
+; GFX6-NEXT:    v_lshlrev_b32_e32 v4, 1, v4
 ; GFX6-NEXT:    v_or_b32_e32 v0, v0, v3
 ; GFX6-NEXT:    v_and_b32_e32 v3, 15, v8
 ; GFX6-NEXT:    v_xor_b32_e32 v6, -1, v8
-; GFX6-NEXT:    v_lshlrev_b32_e32 v4, 1, v4
 ; GFX6-NEXT:    v_and_b32_e32 v6, 15, v6
-; GFX6-NEXT:    v_and_b32_e32 v3, 0xffff, v3
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v1, v3, v1
 ; GFX6-NEXT:    v_bfe_u32 v3, v4, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v6
-; GFX6-NEXT:    v_lshrrev_b32_e32 v3, v4, v3
+; GFX6-NEXT:    v_lshrrev_b32_e32 v3, v6, v3
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v3
 ; GFX6-NEXT:    v_bfe_u32 v3, v5, 1, 15
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v2, 1, v2
@@ -4388,9 +4372,7 @@ define <3 x half> @v_fshr_v3i16(<3 x i16> %lhs, <3 x i16> %rhs, <3 x i16> %amt)
 ; GFX6-NEXT:    v_and_b32_e32 v5, 15, v4
 ; GFX6-NEXT:    v_xor_b32_e32 v4, -1, v4
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v4
-; GFX6-NEXT:    v_and_b32_e32 v5, 0xffff, v5
 ; GFX6-NEXT:    v_bfe_u32 v3, v3, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v4
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v2, v5, v2
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v3, v4, v3
 ; GFX6-NEXT:    v_or_b32_e32 v2, v2, v3
@@ -4782,26 +4764,22 @@ define <4 x half> @v_fshr_v4i16(<4 x i16> %lhs, <4 x i16> %rhs, <4 x i16> %amt)
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v10, 14, v10
 ; GFX6-NEXT:    v_xor_b32_e32 v8, -1, v8
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v10
+; GFX6-NEXT:    v_lshlrev_b32_e32 v4, 1, v4
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v10, 16, v8
 ; GFX6-NEXT:    v_and_b32_e32 v11, 15, v8
 ; GFX6-NEXT:    v_xor_b32_e32 v8, -1, v8
-; GFX6-NEXT:    v_lshlrev_b32_e32 v4, 1, v4
 ; GFX6-NEXT:    v_and_b32_e32 v8, 15, v8
-; GFX6-NEXT:    v_and_b32_e32 v11, 0xffff, v11
 ; GFX6-NEXT:    v_bfe_u32 v4, v4, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v8, 0xffff, v8
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v0, v11, v0
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v8, v4
+; GFX6-NEXT:    v_lshlrev_b32_e32 v5, 1, v5
 ; GFX6-NEXT:    v_or_b32_e32 v0, v0, v4
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v10
 ; GFX6-NEXT:    v_xor_b32_e32 v8, -1, v10
-; GFX6-NEXT:    v_lshlrev_b32_e32 v5, 1, v5
 ; GFX6-NEXT:    v_and_b32_e32 v8, 15, v8
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v4
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v1, v4, v1
 ; GFX6-NEXT:    v_bfe_u32 v4, v5, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v5, 0xffff, v8
-; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v5, v4
+; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v8, v4
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v4
 ; GFX6-NEXT:    v_bfe_u32 v4, v6, 1, 15
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v2, 1, v2
@@ -4818,20 +4796,16 @@ define <4 x half> @v_fshr_v4i16(<4 x i16> %lhs, <4 x i16> %rhs, <4 x i16> %amt)
 ; GFX6-NEXT:    v_and_b32_e32 v8, 15, v6
 ; GFX6-NEXT:    v_xor_b32_e32 v6, -1, v6
 ; GFX6-NEXT:    v_and_b32_e32 v6, 15, v6
-; GFX6-NEXT:    v_and_b32_e32 v8, 0xffff, v8
 ; GFX6-NEXT:    v_bfe_u32 v4, v4, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v6, 0xffff, v6
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v2, v8, v2
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v6, v4
 ; GFX6-NEXT:    v_or_b32_e32 v2, v2, v4
 ; GFX6-NEXT:    v_and_b32_e32 v4, 15, v7
 ; GFX6-NEXT:    v_xor_b32_e32 v6, -1, v7
 ; GFX6-NEXT:    v_and_b32_e32 v6, 15, v6
-; GFX6-NEXT:    v_and_b32_e32 v4, 0xffff, v4
 ; GFX6-NEXT:    v_lshlrev_b32_e32 v3, v4, v3
 ; GFX6-NEXT:    v_bfe_u32 v4, v5, 1, 15
-; GFX6-NEXT:    v_and_b32_e32 v5, 0xffff, v6
-; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v5, v4
+; GFX6-NEXT:    v_lshrrev_b32_e32 v4, v6, v4
 ; GFX6-NEXT:    v_or_b32_e32 v3, v3, v4
 ; GFX6-NEXT:    s_setpc_b64 s[30:31]
 ;



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