From 060ad735fdeb2d4b8cf5a115762e994def2eba67 Mon Sep 17 00:00:00 2001
From: Santiago Aboy Solanes <solanes@google.com>
Date: Thu, 16 Nov 2023 15:35:26 +0000
Subject: Constant fold DivideUnsigned intrinsic

Bug: 309886589
Test: art/test/testrunner/testrunner.py --host --64 -b --optimizing
Change-Id: If60ccbea30b3fe16b86c1630409b540b05b14c56
---
 compiler/optimizing/constant_folding.cc | 51 +++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

(limited to 'compiler/optimizing/constant_folding.cc')

diff --git a/compiler/optimizing/constant_folding.cc b/compiler/optimizing/constant_folding.cc
index 29f5d5caee..66bbf548bb 100644
--- a/compiler/optimizing/constant_folding.cc
+++ b/compiler/optimizing/constant_folding.cc
@@ -60,6 +60,7 @@ class HConstantFoldingVisitor final : public HGraphDelegateVisitor {
   void FoldReverseIntrinsic(HInvoke* invoke);
   void FoldReverseBytesIntrinsic(HInvoke* invoke);
   void FoldBitCountIntrinsic(HInvoke* invoke);
+  void FoldDivideUnsignedIntrinsic(HInvoke* invoke);
   void FoldHighestOneBitIntrinsic(HInvoke* invoke);
   void FoldLowestOneBitIntrinsic(HInvoke* invoke);
   void FoldNumberOfLeadingZerosIntrinsic(HInvoke* invoke);
@@ -379,6 +380,10 @@ void HConstantFoldingVisitor::VisitInvoke(HInvoke* inst) {
     case Intrinsics::kLongBitCount:
       FoldBitCountIntrinsic(inst);
       break;
+    case Intrinsics::kIntegerDivideUnsigned:
+    case Intrinsics::kLongDivideUnsigned:
+      FoldDivideUnsignedIntrinsic(inst);
+      break;
     case Intrinsics::kIntegerHighestOneBit:
     case Intrinsics::kLongHighestOneBit:
       FoldHighestOneBitIntrinsic(inst);
@@ -467,6 +472,52 @@ void HConstantFoldingVisitor::FoldBitCountIntrinsic(HInvoke* inst) {
   inst->GetBlock()->RemoveInstruction(inst);
 }
 
+void HConstantFoldingVisitor::FoldDivideUnsignedIntrinsic(HInvoke* inst) {
+  DCHECK(inst->GetIntrinsic() == Intrinsics::kIntegerDivideUnsigned ||
+         inst->GetIntrinsic() == Intrinsics::kLongDivideUnsigned);
+
+  HInstruction* divisor = inst->InputAt(1);
+  if (!divisor->IsConstant()) {
+    return;
+  }
+  DCHECK_IMPLIES(inst->GetIntrinsic() == Intrinsics::kIntegerDivideUnsigned,
+                 divisor->IsIntConstant());
+  DCHECK_IMPLIES(inst->GetIntrinsic() == Intrinsics::kLongDivideUnsigned,
+                 divisor->IsLongConstant());
+  const bool is_int_intrinsic = inst->GetIntrinsic() == Intrinsics::kIntegerDivideUnsigned;
+  if ((is_int_intrinsic && divisor->AsIntConstant()->IsArithmeticZero()) ||
+      (!is_int_intrinsic && divisor->AsLongConstant()->IsArithmeticZero())) {
+    // We will be throwing, don't constant fold.
+    inst->SetAlwaysThrows(true);
+    GetGraph()->SetHasAlwaysThrowingInvokes(true);
+    return;
+  }
+
+  HInstruction* dividend = inst->InputAt(0);
+  if (!dividend->IsConstant()) {
+    return;
+  }
+  DCHECK_IMPLIES(inst->GetIntrinsic() == Intrinsics::kIntegerDivideUnsigned,
+                 dividend->IsIntConstant());
+  DCHECK_IMPLIES(inst->GetIntrinsic() == Intrinsics::kLongDivideUnsigned,
+                 dividend->IsLongConstant());
+
+  if (is_int_intrinsic) {
+    uint32_t dividend_val =
+        dchecked_integral_cast<uint32_t>(dividend->AsIntConstant()->GetValueAsUint64());
+    uint32_t divisor_val =
+        dchecked_integral_cast<uint32_t>(divisor->AsIntConstant()->GetValueAsUint64());
+    inst->ReplaceWith(GetGraph()->GetIntConstant(static_cast<int32_t>(dividend_val / divisor_val)));
+  } else {
+    uint64_t dividend_val = dividend->AsLongConstant()->GetValueAsUint64();
+    uint64_t divisor_val = divisor->AsLongConstant()->GetValueAsUint64();
+    inst->ReplaceWith(
+        GetGraph()->GetLongConstant(static_cast<int64_t>(dividend_val / divisor_val)));
+  }
+
+  inst->GetBlock()->RemoveInstruction(inst);
+}
+
 void HConstantFoldingVisitor::FoldHighestOneBitIntrinsic(HInvoke* inst) {
   DCHECK(inst->GetIntrinsic() == Intrinsics::kIntegerHighestOneBit ||
          inst->GetIntrinsic() == Intrinsics::kLongHighestOneBit);
-- 
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