Process two 32-bit digits as one 64-bit digit in all bigint intrinsics on x64.

runtime/vm/assembler_x64_test.cc

Index: runtime/vm/assembler_x64_test.cc
===================================================================
--- runtime/vm/assembler_x64_test.cc	(revision 42606)
+++ runtime/vm/assembler_x64_test.cc	(working copy)
@@ -507,6 +507,21 @@
 }
 
 
+ASSEMBLER_TEST_GENERATE(UnsignedMultiplyLong, assembler) {
+  __ movq(RAX, Immediate(-1));  // RAX = 0xFFFFFFFFFFFFFFFF
+  __ movq(RCX, Immediate(16));  // RCX = 0x10
+  __ mulq(RCX);  // RDX:RAX = RAX * RCX = 0x0FFFFFFFFFFFFFFFF0
+  __ movq(RAX, RDX);  // Return high64(0x0FFFFFFFFFFFFFFFF0) == 0x0F
+  __ ret();
+}
+
+
+ASSEMBLER_TEST_RUN(UnsignedMultiplyLong, test) {
+  typedef int64_t (*UnsignedMultiplyLong)();
+  EXPECT_EQ(15, reinterpret_cast<UnsignedMultiplyLong>(test->entry())());
+}
+
+
 ASSEMBLER_TEST_GENERATE(SignedDivide, assembler) {
   __ movl(RAX, Immediate(-87));
   __ movl(RDX, Immediate(123));
@@ -559,6 +574,27 @@
 }
 
 
+ASSEMBLER_TEST_GENERATE(UnsignedDivideLong, assembler) {
+  const int64_t low = 0;
+  const int64_t high = 0xf000000000000000;
+  const int64_t divisor = 0xffffffffffffffff;
+  __ movq(RAX, Immediate(low));
+  __ movq(RDX, Immediate(high));
+  __ movq(RCX, Immediate(divisor));
+  __ divq(RCX);  // RAX = RDX:RAX / RCX =
+                 //     = 0xf0000000000000000000000000000000 /
+                 //       0xffffffffffffffff = 0xf000000000000000
+  __ ret();
+}
+
+
+ASSEMBLER_TEST_RUN(UnsignedDivideLong, test) {
+  typedef uint64_t (*UnsignedDivideLong)();
+  EXPECT_EQ(0xf000000000000000,
+            reinterpret_cast<UnsignedDivideLong>(test->entry())());
+}
+
+
 ASSEMBLER_TEST_GENERATE(Negate, assembler) {
   __ movl(RCX, Immediate(42));
   __ negl(RCX);
@@ -1271,21 +1307,41 @@
   __ movl(Address(RAX, 0), RAX);
   __ Bind(&donetest13a);
 
-  Label donetest15a;
-  const int32_t left = 0xff000000;
-  const int32_t right = 0xffffffff;
-  const int32_t shifted = 0xf0000003;
-  __ movl(RDX, Immediate(left));
-  __ movl(RAX, Immediate(right));
-  __ movl(RCX, Immediate(2));
-  __ shll(RDX, RCX);  // RDX = 0xff000000 << 2 == 0xfc000000
-  __ shldl(RDX, RAX, Immediate(2));  // RDX = high32(0xfc000000:0xffffffff << 2)
-                                     //     = 0xf0000003
-  __ cmpl(RDX, Immediate(shifted));
-  __ j(EQUAL, &donetest15a);
-  __ int3();
-  __ Bind(&donetest15a);
+  {
+    Label donetest15a;
+    const int32_t left = 0xff000000;
+    const int32_t right = 0xffffffff;
+    const int32_t shifted = 0xf0000003;
+    __ movl(RDX, Immediate(left));
+    __ movl(RAX, Immediate(right));
+    __ movl(RCX, Immediate(2));
+    __ shll(RDX, RCX);  // RDX = 0xff000000 << 2 == 0xfc000000
+    __ shldl(RDX, RAX, Immediate(2));
+    // RDX = high32(0xfc000000:0xffffffff << 2) == 0xf0000003
+    __ cmpl(RDX, Immediate(shifted));
+    __ j(EQUAL, &donetest15a);
+    __ int3();
+    __ Bind(&donetest15a);
+  }
 
+  {
+    Label donetest15b;
+    const int64_t left = 0xff00000000000000;
+    const int64_t right = 0xffffffffffffffff;
+    const int64_t shifted = 0xf000000000000003;
+    __ movq(RDX, Immediate(left));
+    __ movq(RAX, Immediate(right));
+    __ movq(RCX, Immediate(2));
+    __ shlq(RDX, RCX);  // RDX = 0xff00000000000000 << 2 == 0xfc00000000000000
+    __ shldq(RDX, RAX, Immediate(2));
+    // RDX = high64(0xfc00000000000000:0xffffffffffffffff << 2)
+    //     == 0xf000000000000003
+    __ cmpq(RDX, Immediate(shifted));
+    __ j(EQUAL, &donetest15b);
+    __ int3();
+    __ Bind(&donetest15b);
+  }
+
   __ movl(RAX, Immediate(0));
   __ ret();
 }