[llvm] [GlobalISel] Handle div-by-pow2 (PR #83155)

via llvm-commits llvm-commits at lists.llvm.org
Wed Feb 28 16:00:09 PST 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-globalisel

@llvm/pr-subscribers-backend-amdgpu

Author: Shilei Tian (shiltian)

<details>
<summary>Changes</summary>

This patch adds similar handling of div-by-pow2 as in `SelectionDAG`.

Fix #<!-- -->80671.

---

Patch is 138.16 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/83155.diff


4 Files Affected:

- (modified) llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h (+10) 
- (modified) llvm/include/llvm/Target/GlobalISel/Combine.td (+17-4) 
- (modified) llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp (+101-1) 
- (modified) llvm/test/CodeGen/AMDGPU/div_i128.ll (+2281-9) 


``````````diff
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h b/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
index 23728636498ba0..c19efba984d0d9 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
@@ -673,6 +673,16 @@ class CombinerHelper {
   bool matchSDivByConst(MachineInstr &MI);
   void applySDivByConst(MachineInstr &MI);
 
+  /// Given an G_SDIV \p MI expressing a signed divided by a pow2 constant,
+  /// return expressions that implements it by shifting.
+  bool matchSDivByPow2(MachineInstr &MI);
+  void applySDivByPow2(MachineInstr &MI);
+
+  /// Given an G_UDIV \p MI expressing an unsigned divided by a pow2 constant,
+  /// return expressions that implements it by shifting.
+  bool matchUDivByPow2(MachineInstr &MI);
+  void applyUDivByPow2(MachineInstr &MI);
+
   // G_UMULH x, (1 << c)) -> x >> (bitwidth - c)
   bool matchUMulHToLShr(MachineInstr &MI);
   void applyUMulHToLShr(MachineInstr &MI);
diff --git a/llvm/include/llvm/Target/GlobalISel/Combine.td b/llvm/include/llvm/Target/GlobalISel/Combine.td
index 17757ca3e41111..1d9a60bd27e7ac 100644
--- a/llvm/include/llvm/Target/GlobalISel/Combine.td
+++ b/llvm/include/llvm/Target/GlobalISel/Combine.td
@@ -264,7 +264,7 @@ def combine_extracted_vector_load : GICombineRule<
   (match (wip_match_opcode G_EXTRACT_VECTOR_ELT):$root,
         [{ return Helper.matchCombineExtractedVectorLoad(*${root}, ${matchinfo}); }]),
   (apply [{ Helper.applyBuildFn(*${root}, ${matchinfo}); }])>;
-  
+
 def combine_indexed_load_store : GICombineRule<
   (defs root:$root, indexed_load_store_matchdata:$matchinfo),
   (match (wip_match_opcode G_LOAD, G_SEXTLOAD, G_ZEXTLOAD, G_STORE):$root,
@@ -1005,7 +1005,20 @@ def sdiv_by_const : GICombineRule<
    [{ return Helper.matchSDivByConst(*${root}); }]),
   (apply [{ Helper.applySDivByConst(*${root}); }])>;
 
-def intdiv_combines : GICombineGroup<[udiv_by_const, sdiv_by_const]>;
+def sdiv_by_pow2 : GICombineRule<
+  (defs root:$root),
+  (match (wip_match_opcode G_SDIV):$root,
+   [{ return Helper.matchSDivByPow2(*${root}); }]),
+  (apply [{ Helper.applySDivByPow2(*${root}); }])>;
+
+def udiv_by_pow2 : GICombineRule<
+  (defs root:$root),
+  (match (wip_match_opcode G_UDIV):$root,
+   [{ return Helper.matchUDivByPow2(*${root}); }]),
+  (apply [{ Helper.applyUDivByPow2(*${root}); }])>;
+
+def intdiv_combines : GICombineGroup<[udiv_by_const, sdiv_by_const,
+                                      sdiv_by_pow2, udiv_by_pow2]>;
 
 def reassoc_ptradd : GICombineRule<
   (defs root:$root, build_fn_matchinfo:$matchinfo),
@@ -1325,7 +1338,7 @@ def constant_fold_binops : GICombineGroup<[constant_fold_binop,
 
 def all_combines : GICombineGroup<[trivial_combines, insert_vec_elt_combines,
     extract_vec_elt_combines, combines_for_extload, combine_extracted_vector_load,
-    undef_combines, identity_combines, phi_combines, 
+    undef_combines, identity_combines, phi_combines,
     simplify_add_to_sub, hoist_logic_op_with_same_opcode_hands, shifts_too_big,
     reassocs, ptr_add_immed_chain,
     shl_ashr_to_sext_inreg, sext_inreg_of_load,
@@ -1342,7 +1355,7 @@ def all_combines : GICombineGroup<[trivial_combines, insert_vec_elt_combines,
     intdiv_combines, mulh_combines, redundant_neg_operands,
     and_or_disjoint_mask, fma_combines, fold_binop_into_select,
     sub_add_reg, select_to_minmax, redundant_binop_in_equality,
-    fsub_to_fneg, commute_constant_to_rhs, match_ands, match_ors, 
+    fsub_to_fneg, commute_constant_to_rhs, match_ands, match_ors,
     combine_concat_vector]>;
 
 // A combine group used to for prelegalizer combiners at -O0. The combines in
diff --git a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
index 2f18a64ca285bd..d094fcd0ec3af8 100644
--- a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -1490,7 +1490,7 @@ void CombinerHelper::applyOptBrCondByInvertingCond(MachineInstr &MI,
   Observer.changedInstr(*BrCond);
 }
 
- 
+
 bool CombinerHelper::tryEmitMemcpyInline(MachineInstr &MI) {
   MachineIRBuilder HelperBuilder(MI);
   GISelObserverWrapper DummyObserver;
@@ -5286,6 +5286,106 @@ MachineInstr *CombinerHelper::buildSDivUsingMul(MachineInstr &MI) {
   return MIB.buildMul(Ty, Res, Factor);
 }
 
+bool CombinerHelper::matchSDivByPow2(MachineInstr &MI) {
+  assert(MI.getOpcode() == TargetOpcode::G_SDIV && "Expected SDIV");
+  if (MI.getFlag(MachineInstr::MIFlag::IsExact))
+    return false;
+  auto &SDiv = cast<GenericMachineInstr>(MI);
+  Register RHS = SDiv.getReg(2);
+  auto MatchPow2 = [&](const Constant *C) {
+    if (auto *CI = dyn_cast<ConstantInt>(C))
+      return CI->getValue().isPowerOf2() || CI->getValue().isNegatedPowerOf2();
+    return false;
+  };
+  return matchUnaryPredicate(MRI, RHS, MatchPow2, /* AllowUndefs */ false);
+}
+
+void CombinerHelper::applySDivByPow2(MachineInstr &MI) {
+  assert(MI.getOpcode() == TargetOpcode::G_SDIV && "Expected SDIV");
+  auto &SDiv = cast<GenericMachineInstr>(MI);
+  Register Dst = SDiv.getReg(0);
+  Register LHS = SDiv.getReg(1);
+  Register RHS = SDiv.getReg(2);
+  LLT Ty = MRI.getType(Dst);
+  LLT ShiftAmtTy = getTargetLowering().getPreferredShiftAmountTy(Ty);
+
+  Builder.setInstrAndDebugLoc(MI);
+
+  auto RHSC = getIConstantVRegValWithLookThrough(RHS, MRI);
+  assert(RHSC.has_value() && "RHS must be a constant");
+  auto RHSCV = RHSC->Value;
+  auto Zero = Builder.buildConstant(Ty, 0);
+
+  // Special case: (sdiv X, 1) -> X
+  if (RHSCV.isOne()) {
+    replaceSingleDefInstWithReg(MI, LHS);
+    return;
+  }
+  // Special Case: (sdiv X, -1) -> 0-X
+  if (RHSCV.isAllOnes()) {
+    auto Sub = Builder.buildSub(Ty, Zero, LHS);
+    replaceSingleDefInstWithReg(MI, Sub->getOperand(0).getReg());
+    return;
+  }
+
+  unsigned Bitwidth = Ty.getScalarSizeInBits();
+  unsigned TrailingZeros = RHSCV.countTrailingZeros();
+  auto C1 = Builder.buildConstant(ShiftAmtTy, TrailingZeros);
+  auto Inexact = Builder.buildConstant(ShiftAmtTy, Bitwidth - TrailingZeros);
+  auto Sign = Builder.buildAShr(
+      Ty, LHS, Builder.buildConstant(ShiftAmtTy, Bitwidth - 1));
+  // Add (LHS < 0) ? abs2 - 1 : 0;
+  auto Srl = Builder.buildShl(Ty, Sign, Inexact);
+  auto Add = Builder.buildAdd(Ty, LHS, Srl);
+  auto Sra = Builder.buildAShr(Ty, Add, C1);
+
+  // If dividing by a positive value, we're done. Otherwise, the result must
+  // be negated.
+  auto Res = RHSCV.isNegative() ? Builder.buildSub(Ty, Zero, Sra) : Sra;
+  replaceSingleDefInstWithReg(MI, Res->getOperand(0).getReg());
+}
+
+bool CombinerHelper::matchUDivByPow2(MachineInstr &MI) {
+  assert(MI.getOpcode() == TargetOpcode::G_UDIV && "Expected UDIV");
+  if (MI.getFlag(MachineInstr::MIFlag::IsExact))
+    return false;
+  auto &UDiv = cast<GenericMachineInstr>(MI);
+  Register RHS = UDiv.getReg(2);
+  auto MatchPow2 = [&](const Constant *C) {
+    if (auto *CI = dyn_cast<ConstantInt>(C))
+      return CI->getValue().isPowerOf2();
+    return false;
+  };
+  return matchUnaryPredicate(MRI, RHS, MatchPow2, /* AllowUndefs */ false);
+}
+
+void CombinerHelper::applyUDivByPow2(MachineInstr &MI) {
+  assert(MI.getOpcode() == TargetOpcode::G_UDIV && "Expected SDIV");
+  auto &UDiv = cast<GenericMachineInstr>(MI);
+  Register Dst = UDiv.getReg(0);
+  Register LHS = UDiv.getReg(1);
+  Register RHS = UDiv.getReg(2);
+  LLT Ty = MRI.getType(Dst);
+  LLT ShiftAmtTy = getTargetLowering().getPreferredShiftAmountTy(Ty);
+
+  Builder.setInstrAndDebugLoc(MI);
+
+  auto RHSC = getIConstantVRegValWithLookThrough(RHS, MRI);
+  assert(RHSC.has_value() && "RHS must be a constant");
+  auto RHSCV = RHSC->Value;
+
+  // Special case: (udiv X, 1) -> X
+  if (RHSCV.isOne()) {
+    replaceSingleDefInstWithReg(MI, LHS);
+    return;
+  }
+
+  unsigned TrailingZeros = RHSCV.countTrailingZeros();
+  auto C1 = Builder.buildConstant(ShiftAmtTy, TrailingZeros);
+  auto Res = Builder.buildLShr(Ty, LHS, C1);
+  replaceSingleDefInstWithReg(MI, Res->getOperand(0).getReg());
+}
+
 bool CombinerHelper::matchUMulHToLShr(MachineInstr &MI) {
   assert(MI.getOpcode() == TargetOpcode::G_UMULH);
   Register RHS = MI.getOperand(2).getReg();
diff --git a/llvm/test/CodeGen/AMDGPU/div_i128.ll b/llvm/test/CodeGen/AMDGPU/div_i128.ll
index 2f3d5d9d140c2c..8073d06dab5970 100644
--- a/llvm/test/CodeGen/AMDGPU/div_i128.ll
+++ b/llvm/test/CodeGen/AMDGPU/div_i128.ll
@@ -1,10 +1,9 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
-; RUN: llc -global-isel=0 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o - %s | FileCheck -check-prefixes=GFX9,GFX9-SDAG %s
-; RUN: llc -O0 -global-isel=0 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o - %s | FileCheck -check-prefixes=GFX9-O0,GFX9-SDAG-O0 %s
+; RUN: llc -global-isel=0 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o - %s | FileCheck -check-prefixes=GFX9 %s
+; RUN: llc -O0 -global-isel=0 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o - %s | FileCheck -check-prefixes=GFX9-O0 %s
 
-; FIXME: GlobalISel missing the power-of-2 cases in legalization. https://github.com/llvm/llvm-project/issues/80671
-; xUN: llc -global-isel=1 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o - %s | FileCheck -check-prefixes=GFX9,GFX9 %s
-; xUN: llc -O0 -global-isel=1 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o - %s | FileCheck -check-prefixes=GFX9-O0,GFX9-O0 %s
+; RUN: llc -global-isel=1 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o - %s | FileCheck -check-prefixes=GFX9-G %s
+; RUN: llc -O0 -global-isel=1 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o - %s | FileCheck -check-prefixes=GFX9-G-O0 %s
 
 define i128 @v_sdiv_i128_vv(i128 %lhs, i128 %rhs) {
 ; GFX9-LABEL: v_sdiv_i128_vv:
@@ -1223,6 +1222,1158 @@ define i128 @v_sdiv_i128_vv(i128 %lhs, i128 %rhs) {
 ; GFX9-O0-NEXT:    s_mov_b64 exec, s[4:5]
 ; GFX9-O0-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-O0-NEXT:    s_setpc_b64 s[30:31]
+;
+; GFX9-G-LABEL: v_sdiv_i128_vv:
+; GFX9-G:       ; %bb.0: ; %_udiv-special-cases
+; GFX9-G-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-G-NEXT:    v_ashrrev_i32_e32 v16, 31, v3
+; GFX9-G-NEXT:    v_xor_b32_e32 v0, v16, v0
+; GFX9-G-NEXT:    v_xor_b32_e32 v1, v16, v1
+; GFX9-G-NEXT:    v_sub_co_u32_e32 v10, vcc, v0, v16
+; GFX9-G-NEXT:    v_xor_b32_e32 v2, v16, v2
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v11, vcc, v1, v16, vcc
+; GFX9-G-NEXT:    v_ashrrev_i32_e32 v17, 31, v7
+; GFX9-G-NEXT:    v_xor_b32_e32 v3, v16, v3
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v12, vcc, v2, v16, vcc
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v13, vcc, v3, v16, vcc
+; GFX9-G-NEXT:    v_xor_b32_e32 v0, v17, v4
+; GFX9-G-NEXT:    v_xor_b32_e32 v1, v17, v5
+; GFX9-G-NEXT:    v_sub_co_u32_e32 v18, vcc, v0, v17
+; GFX9-G-NEXT:    v_xor_b32_e32 v2, v17, v6
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v19, vcc, v1, v17, vcc
+; GFX9-G-NEXT:    v_xor_b32_e32 v3, v17, v7
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v4, vcc, v2, v17, vcc
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v5, vcc, v3, v17, vcc
+; GFX9-G-NEXT:    v_or_b32_e32 v0, v18, v4
+; GFX9-G-NEXT:    v_or_b32_e32 v1, v19, v5
+; GFX9-G-NEXT:    v_cmp_eq_u64_e32 vcc, 0, v[0:1]
+; GFX9-G-NEXT:    v_or_b32_e32 v0, v10, v12
+; GFX9-G-NEXT:    v_or_b32_e32 v1, v11, v13
+; GFX9-G-NEXT:    v_cmp_eq_u64_e64 s[4:5], 0, v[0:1]
+; GFX9-G-NEXT:    v_ffbh_u32_e32 v1, v18
+; GFX9-G-NEXT:    v_ffbh_u32_e32 v0, v19
+; GFX9-G-NEXT:    v_add_u32_e32 v1, 32, v1
+; GFX9-G-NEXT:    v_ffbh_u32_e32 v2, v4
+; GFX9-G-NEXT:    v_min_u32_e32 v0, v0, v1
+; GFX9-G-NEXT:    v_ffbh_u32_e32 v1, v5
+; GFX9-G-NEXT:    v_add_u32_e32 v2, 32, v2
+; GFX9-G-NEXT:    v_cmp_eq_u64_e64 s[6:7], 0, v[4:5]
+; GFX9-G-NEXT:    v_add_u32_e32 v0, 64, v0
+; GFX9-G-NEXT:    v_min_u32_e32 v1, v1, v2
+; GFX9-G-NEXT:    v_ffbh_u32_e32 v2, v10
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v0, v1, v0, s[6:7]
+; GFX9-G-NEXT:    v_ffbh_u32_e32 v1, v11
+; GFX9-G-NEXT:    v_add_u32_e32 v2, 32, v2
+; GFX9-G-NEXT:    v_ffbh_u32_e32 v3, v12
+; GFX9-G-NEXT:    v_min_u32_e32 v1, v1, v2
+; GFX9-G-NEXT:    v_ffbh_u32_e32 v2, v13
+; GFX9-G-NEXT:    v_add_u32_e32 v3, 32, v3
+; GFX9-G-NEXT:    v_cmp_eq_u64_e64 s[6:7], 0, v[12:13]
+; GFX9-G-NEXT:    v_add_u32_e32 v1, 64, v1
+; GFX9-G-NEXT:    v_min_u32_e32 v2, v2, v3
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v1, v2, v1, s[6:7]
+; GFX9-G-NEXT:    v_sub_co_u32_e64 v0, s[6:7], v0, v1
+; GFX9-G-NEXT:    v_subb_co_u32_e64 v1, s[6:7], 0, 0, s[6:7]
+; GFX9-G-NEXT:    v_mov_b32_e32 v6, 0x7f
+; GFX9-G-NEXT:    v_subb_co_u32_e64 v2, s[6:7], 0, 0, s[6:7]
+; GFX9-G-NEXT:    v_mov_b32_e32 v7, 0
+; GFX9-G-NEXT:    v_subb_co_u32_e64 v3, s[6:7], 0, 0, s[6:7]
+; GFX9-G-NEXT:    v_cmp_gt_u64_e64 s[6:7], v[0:1], v[6:7]
+; GFX9-G-NEXT:    s_or_b64 s[4:5], vcc, s[4:5]
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v6, 0, 1, s[6:7]
+; GFX9-G-NEXT:    v_cmp_lt_u64_e64 s[6:7], 0, v[2:3]
+; GFX9-G-NEXT:    v_or_b32_e32 v15, v1, v3
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v7, 0, 1, s[6:7]
+; GFX9-G-NEXT:    v_cmp_eq_u64_e64 s[6:7], 0, v[2:3]
+; GFX9-G-NEXT:    s_mov_b64 s[8:9], 0
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v6, v7, v6, s[6:7]
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v7, 0, 1, s[4:5]
+; GFX9-G-NEXT:    v_or_b32_e32 v20, v7, v6
+; GFX9-G-NEXT:    v_xor_b32_e32 v6, 0x7f, v0
+; GFX9-G-NEXT:    v_or_b32_e32 v14, v6, v2
+; GFX9-G-NEXT:    v_and_b32_e32 v6, 1, v20
+; GFX9-G-NEXT:    v_cmp_ne_u32_e32 vcc, 0, v6
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v6, v10, 0, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v7, v11, 0, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v8, v12, 0, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v9, v13, 0, vcc
+; GFX9-G-NEXT:    v_cmp_eq_u64_e32 vcc, 0, v[14:15]
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v14, 0, 1, vcc
+; GFX9-G-NEXT:    v_or_b32_e32 v14, v20, v14
+; GFX9-G-NEXT:    v_and_b32_e32 v14, 1, v14
+; GFX9-G-NEXT:    v_cmp_ne_u32_e32 vcc, 0, v14
+; GFX9-G-NEXT:    s_xor_b64 s[4:5], vcc, -1
+; GFX9-G-NEXT:    s_and_saveexec_b64 s[6:7], s[4:5]
+; GFX9-G-NEXT:    s_cbranch_execz .LBB0_6
+; GFX9-G-NEXT:  ; %bb.1: ; %udiv-bb1
+; GFX9-G-NEXT:    v_add_co_u32_e32 v20, vcc, 1, v0
+; GFX9-G-NEXT:    v_addc_co_u32_e32 v21, vcc, 0, v1, vcc
+; GFX9-G-NEXT:    v_addc_co_u32_e32 v22, vcc, 0, v2, vcc
+; GFX9-G-NEXT:    v_addc_co_u32_e32 v23, vcc, 0, v3, vcc
+; GFX9-G-NEXT:    s_xor_b64 s[4:5], vcc, -1
+; GFX9-G-NEXT:    v_sub_co_u32_e32 v8, vcc, 0x7f, v0
+; GFX9-G-NEXT:    v_sub_u32_e32 v0, 64, v8
+; GFX9-G-NEXT:    v_lshrrev_b64 v[0:1], v0, v[10:11]
+; GFX9-G-NEXT:    v_lshlrev_b64 v[2:3], v8, v[12:13]
+; GFX9-G-NEXT:    v_subrev_u32_e32 v9, 64, v8
+; GFX9-G-NEXT:    v_lshlrev_b64 v[6:7], v8, v[10:11]
+; GFX9-G-NEXT:    v_or_b32_e32 v2, v0, v2
+; GFX9-G-NEXT:    v_or_b32_e32 v3, v1, v3
+; GFX9-G-NEXT:    v_lshlrev_b64 v[0:1], v9, v[10:11]
+; GFX9-G-NEXT:    v_cmp_gt_u32_e32 vcc, 64, v8
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v6, 0, v6, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v7, 0, v7, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v0, v0, v2, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v1, v1, v3, vcc
+; GFX9-G-NEXT:    v_cmp_eq_u32_e32 vcc, 0, v8
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v8, v0, v12, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v9, v1, v13, vcc
+; GFX9-G-NEXT:    s_mov_b64 s[10:11], s[8:9]
+; GFX9-G-NEXT:    v_mov_b32_e32 v0, s8
+; GFX9-G-NEXT:    v_mov_b32_e32 v1, s9
+; GFX9-G-NEXT:    v_mov_b32_e32 v2, s10
+; GFX9-G-NEXT:    v_mov_b32_e32 v3, s11
+; GFX9-G-NEXT:    s_and_saveexec_b64 s[8:9], s[4:5]
+; GFX9-G-NEXT:    s_xor_b64 s[12:13], exec, s[8:9]
+; GFX9-G-NEXT:    s_cbranch_execz .LBB0_5
+; GFX9-G-NEXT:  ; %bb.2: ; %udiv-preheader
+; GFX9-G-NEXT:    v_sub_u32_e32 v2, 64, v20
+; GFX9-G-NEXT:    v_lshrrev_b64 v[0:1], v20, v[10:11]
+; GFX9-G-NEXT:    v_lshlrev_b64 v[2:3], v2, v[12:13]
+; GFX9-G-NEXT:    v_subrev_u32_e32 v24, 64, v20
+; GFX9-G-NEXT:    v_lshrrev_b64 v[14:15], v20, v[12:13]
+; GFX9-G-NEXT:    v_or_b32_e32 v2, v0, v2
+; GFX9-G-NEXT:    v_or_b32_e32 v3, v1, v3
+; GFX9-G-NEXT:    v_lshrrev_b64 v[0:1], v24, v[12:13]
+; GFX9-G-NEXT:    v_cmp_gt_u32_e32 vcc, 64, v20
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v0, v0, v2, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v1, v1, v3, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v14, 0, v14, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e32 v15, 0, v15, vcc
+; GFX9-G-NEXT:    v_add_co_u32_e32 v24, vcc, -1, v18
+; GFX9-G-NEXT:    s_mov_b64 s[8:9], 0
+; GFX9-G-NEXT:    v_cmp_eq_u32_e64 s[4:5], 0, v20
+; GFX9-G-NEXT:    v_addc_co_u32_e32 v25, vcc, -1, v19, vcc
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v12, v0, v10, s[4:5]
+; GFX9-G-NEXT:    v_cndmask_b32_e64 v13, v1, v11, s[4:5]
+; GFX9-G-NEXT:    v_addc_co_u32_e32 v26, vcc, -1, v4, vcc
+; GFX9-G-NEXT:    s_mov_b64 s[10:11], s[8:9]
+; GFX9-G-NEXT:    v_mov_b32_e32 v0, s8
+; GFX9-G-NEXT:    v_addc_co_u32_e32 v27, vcc, -1, v5, vcc
+; GFX9-G-NEXT:    v_mov_b32_e32 v11, 0
+; GFX9-G-NEXT:    v_mov_b32_e32 v1, s9
+; GFX9-G-NEXT:    v_mov_b32_e32 v2, s10
+; GFX9-G-NEXT:    v_mov_b32_e32 v3, s11
+; GFX9-G-NEXT:  .LBB0_3: ; %udiv-do-while
+; GFX9-G-NEXT:    ; =>This Inner Loop Header: Depth=1
+; GFX9-G-NEXT:    v_lshlrev_b64 v[2:3], 1, v[6:7]
+; GFX9-G-NEXT:    v_lshrrev_b32_e32 v10, 31, v7
+; GFX9-G-NEXT:    v_or_b32_e32 v6, v0, v2
+; GFX9-G-NEXT:    v_or_b32_e32 v7, v1, v3
+; GFX9-G-NEXT:    v_lshlrev_b64 v[2:3], 1, v[12:13]
+; GFX9-G-NEXT:    v_lshrrev_b32_e32 v12, 31, v9
+; GFX9-G-NEXT:    v_lshlrev_b64 v[0:1], 1, v[14:15]
+; GFX9-G-NEXT:    v_or_b32_e32 v2, v2, v12
+; GFX9-G-NEXT:    v_lshrrev_b32_e32 v14, 31, v13
+; GFX9-G-NEXT:    v_sub_co_u32_e32 v12, vcc, v24, v2
+; GFX9-G-NEXT:    v_or_b32_e32 v0, v0, v14
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v12, vcc, v25, v3, vcc
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v12, vcc, v26, v0, vcc
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v12, vcc, v27, v1, vcc
+; GFX9-G-NEXT:    v_ashrrev_i32_e32 v28, 31, v12
+; GFX9-G-NEXT:    v_and_b32_e32 v12, v28, v18
+; GFX9-G-NEXT:    v_sub_co_u32_e32 v12, vcc, v2, v12
+; GFX9-G-NEXT:    v_and_b32_e32 v2, v28, v19
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v13, vcc, v3, v2, vcc
+; GFX9-G-NEXT:    v_and_b32_e32 v2, v28, v4
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v14, vcc, v0, v2, vcc
+; GFX9-G-NEXT:    v_and_b32_e32 v0, v28, v5
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v15, vcc, v1, v0, vcc
+; GFX9-G-NEXT:    v_add_co_u32_e32 v20, vcc, -1, v20
+; GFX9-G-NEXT:    v_addc_co_u32_e32 v21, vcc, -1, v21, vcc
+; GFX9-G-NEXT:    v_addc_co_u32_e32 v22, vcc, -1, v22, vcc
+; GFX9-G-NEXT:    v_addc_co_u32_e32 v23, vcc, -1, v23, vcc
+; GFX9-G-NEXT:    v_lshlrev_b64 v[8:9], 1, v[8:9]
+; GFX9-G-NEXT:    v_or_b32_e32 v0, v20, v22
+; GFX9-G-NEXT:    v_or_b32_e32 v1, v21, v23
+; GFX9-G-NEXT:    v_cmp_eq_u64_e32 vcc, 0, v[0:1]
+; GFX9-G-NEXT:    v_or_b32_e32 v8, v8, v10
+; GFX9-G-NEXT:    v_and_b32_e32 v10, 1, v28
+; GFX9-G-NEXT:    v_mov_b32_e32 v0, v10
+; GFX9-G-NEXT:    s_or_b64 s[8:9], vcc, s[8:9]
+; GFX9-G-NEXT:    v_mov_b32_e32 v1, v11
+; GFX9-G-NEXT:    s_andn2_b64 exec, exec, s[8:9]
+; GFX9-G-NEXT:    s_cbranch_execnz .LBB0_3
+; GFX9-G-NEXT:  ; %bb.4: ; %Flow
+; GFX9-G-NEXT:    s_or_b64 exec, exec, s[8:9]
+; GFX9-G-NEXT:  .LBB0_5: ; %Flow2
+; GFX9-G-NEXT:    s_or_b64 exec, exec, s[12:13]
+; GFX9-G-NEXT:    v_lshlrev_b64 v[2:3], 1, v[6:7]
+; GFX9-G-NEXT:    v_lshlrev_b64 v[8:9], 1, v[8:9]
+; GFX9-G-NEXT:    v_lshrrev_b32_e32 v4, 31, v7
+; GFX9-G-NEXT:    v_or_b32_e32 v8, v8, v4
+; GFX9-G-NEXT:    v_or_b32_e32 v6, v0, v2
+; GFX9-G-NEXT:    v_or_b32_e32 v7, v1, v3
+; GFX9-G-NEXT:  .LBB0_6: ; %Flow3
+; GFX9-G-NEXT:    s_or_b64 exec, exec, s[6:7]
+; GFX9-G-NEXT:    v_xor_b32_e32 v3, v17, v16
+; GFX9-G-NEXT:    v_xor_b32_e32 v0, v6, v3
+; GFX9-G-NEXT:    v_xor_b32_e32 v1, v7, v3
+; GFX9-G-NEXT:    v_sub_co_u32_e32 v0, vcc, v0, v3
+; GFX9-G-NEXT:    v_xor_b32_e32 v2, v8, v3
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v1, vcc, v1, v3, vcc
+; GFX9-G-NEXT:    v_xor_b32_e32 v4, v9, v3
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v2, vcc, v2, v3, vcc
+; GFX9-G-NEXT:    v_subb_co_u32_e32 v3, vcc, v4, v3, vcc
+; GFX9-G-NEXT:    s_setpc_b64 s[30:31]
+;
+; GFX9-G-O0-LABEL: v_sdiv_i128_vv:
+; GFX9-G-O0:       ; %bb.0: ; %_udiv-special-cases
+; GFX9-G-O0-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GFX9-G-O0-NEXT:    s_xor_saveexec_b64 s[4:5], -1
+; GFX9-G-O0-NEXT:    buffer_store_dword v0, off, s[0:3], s32 offset:328 ; 4-byte Folded Spill
+; GFX9-G-O0-NEXT:    buffer_store_dword v4, off, s[0:3], s32 offset:332 ; 4-byte Folded Spill
+; GFX9-G-O0-NEXT:    buffer_store_dword v8, off, s[0:3], s32 offset:336 ; 4-byte Folded Spill
+; GFX9-G-O0-NEXT:    buffer_store_dword v16, off, s[0:3], s32 offset:340 ; 4-byte Folded Spill
+; GFX9-G-O0-NEX...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/83155


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