[wasm] Int64Lowering of Int64Sub on ia32 and arm.

test/cctest/compiler/test-run-machops.cc

 // Copyright 2014 the V8 project authors. All rights reserved. Use of this
 // source code is governed by a BSD-style license that can be found in the
 // LICENSE file.
 
 #include <cmath>
 #include <functional>
 #include <limits>
 
 #include "src/base/bits.h"
 #include "src/base/utils/random-number-generator.h"
@@ skipping 4179 matching lines @@
 
 
 TEST(RunTruncateFloat64ToFloat32) {
   BufferedRawMachineAssemblerTester<float> m(MachineType::Float64());
 
   m.Return(m.TruncateFloat64ToFloat32(m.Parameter(0)));
 
   FOR_FLOAT64_INPUTS(i) { CHECK_FLOAT_EQ(DoubleToFloat32(*i), m.Call(*i)); }
 }
 
 int64_t ToInt64(uint32_t low, uint32_t high) {

[titzer, 2016/03/14 09:36:06]

You have to make this uint64_t to avoid undefined behavior on overflow.

[ahaas, 2016/03/15 11:01:43]

I think this function works as intended. To clarify my intentions I renamed the
function to BitcastToInt64.

[titzer, 2016/03/15 11:05:39]

Below, you are doing arithmetic on int64_t values without checking for overflow;
this is UB in C++, unfortunately.

   return (static_cast<int64_t>(high) << 32) | static_cast<int64_t>(low);
 }
 
 #if V8_TARGET_ARCH_32_BIT
+

[titzer, 2016/03/14 09:36:06]

Stray blank line

[ahaas, 2016/03/15 11:01:43]

Removed.

 TEST(RunInt32PairAdd) {
   BufferedRawMachineAssemblerTester<int32_t> m(
       MachineType::Int32(), MachineType::Int32(), MachineType::Int32(),
       MachineType::Int32());
 
   uint32_t high;
   uint32_t low;
 
   Node* PairAdd = m.Int32PairAdd(m.Parameter(0), m.Parameter(1), m.Parameter(2),
                                  m.Parameter(3));
@@ skipping 42 matching lines @@
 }
 
 TEST(RunInt32PairAddWithSharedInput) {
   TestInt32PairAddWithSharedInput(0, 0, 0, 0);
   TestInt32PairAddWithSharedInput(1, 0, 0, 0);
   TestInt32PairAddWithSharedInput(0, 1, 0, 0);
   TestInt32PairAddWithSharedInput(0, 0, 1, 0);
   TestInt32PairAddWithSharedInput(0, 0, 0, 1);
   TestInt32PairAddWithSharedInput(1, 1, 0, 0);
 }
+
+TEST(RunInt32PairSub) {
+  BufferedRawMachineAssemblerTester<int32_t> m(
+      MachineType::Int32(), MachineType::Int32(), MachineType::Int32(),
+      MachineType::Int32());
+
+  uint32_t high;
+  uint32_t low;
+
+  Node* PairSub = m.Int32PairSub(m.Parameter(0), m.Parameter(1), m.Parameter(2),
+                                 m.Parameter(3));
+
+  m.StoreToPointer(&low, MachineRepresentation::kWord32,

[titzer, 2016/03/14 09:36:06]

Why do you need to use memory here? 

[ahaas, 2016/03/15 11:01:43]

The BufferedRawMachineAssemblerTester does not support 64 bit returns on 32 bit
platforms.

+                   m.Projection(0, PairSub));
+  m.StoreToPointer(&high, MachineRepresentation::kWord32,
+                   m.Projection(1, PairSub));
+  m.Return(m.Int32Constant(74));
+
+  FOR_INT64_INPUTS(i) {
+    FOR_INT64_INPUTS(j) {
+      m.Call(static_cast<int32_t>(*i & 0xffffffff),
+             static_cast<int32_t>(*i >> 32),
+             static_cast<int32_t>(*j & 0xffffffff),
+             static_cast<int32_t>(*j >> 32));
+      CHECK_EQ(*i - *j, ToInt64(low, high));
+    }
+  }
+}
+
+void TestInt32PairSubWithSharedInput(int a, int b, int c, int d) {
+  BufferedRawMachineAssemblerTester<int32_t> m(MachineType::Uint32(),
+                                               MachineType::Uint32());
+
+  uint32_t high;
+  uint32_t low;
+
+  Node* PairSub = m.Int32PairSub(m.Parameter(a), m.Parameter(b), m.Parameter(c),
+                                 m.Parameter(d));
+
+  m.StoreToPointer(&low, MachineRepresentation::kWord32,
+                   m.Projection(0, PairSub));
+  m.StoreToPointer(&high, MachineRepresentation::kWord32,
+                   m.Projection(1, PairSub));
+  m.Return(m.Int32Constant(74));
+
+  FOR_UINT32_INPUTS(i) {
+    FOR_UINT32_INPUTS(j) {
+      m.Call(*i, *j);
+      uint32_t inputs[] = {*i, *j};
+      CHECK_EQ(ToInt64(inputs[a], inputs[b]) - ToInt64(inputs[c], inputs[d]),
+               ToInt64(low, high));
+    }
+  }
+}
+
+TEST(RunInt32PairSubWithSharedInput) {
+  TestInt32PairSubWithSharedInput(0, 0, 0, 0);
+  TestInt32PairSubWithSharedInput(1, 0, 0, 0);
+  TestInt32PairSubWithSharedInput(0, 1, 0, 0);
+  TestInt32PairSubWithSharedInput(0, 0, 1, 0);
+  TestInt32PairSubWithSharedInput(0, 0, 0, 1);
+  TestInt32PairSubWithSharedInput(1, 1, 0, 0);
+}
 #endif
 
 TEST(RunDeadChangeFloat64ToInt32) {
   RawMachineAssemblerTester<int32_t> m;
   const int magic = 0x88abcda4;
   m.ChangeFloat64ToInt32(m.Float64Constant(999.78));
   m.Return(m.Int32Constant(magic));
   CHECK_EQ(magic, m.Call());
 }
 
@@ skipping 1918 matching lines @@
   r.Goto(&merge);
   r.Bind(&merge);
   Node* phi = r.Phi(MachineRepresentation::kWord32, fa, fb);
   r.Return(phi);
   CHECK_EQ(1, r.Call(1));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8