[VM] ARM64: Fix tbz instruction for bit positions >= 32

[email protected]

Change-Id: I03f42ee44a37da7e064f79db18a7f45fa25ee010
Reviewed-on: https://dart-review.googlesource.com/46063
Reviewed-by: Martin Kustermann <[email protected]>

Author: ErikCorryGoogle

assembler_arm64.h

@@ -1841,9 +1841,11 @@ class Assembler : public ValueObject {
     ASSERT(Utils::IsInt(16, imm) && ((imm & 0x3) == 0));
     ASSERT((rt != CSP) && (rt != R31));
     const Register crt = ConcreteRegister(rt);
-    const int32_t encoding = op | (static_cast<int32_t>(bit_number) << 19) |
-                             (static_cast<int32_t>(crt) << kRtShift) |
-                             encoded_offset;
+    int32_t bit_number_low = bit_number & 0x1f;
+    int32_t bit_number_hi = (bit_number & 0x20) >> 5;
+    const int32_t encoding =
+        op | (bit_number_low << 19) | (bit_number_hi << 31) |
+        (static_cast<int32_t>(crt) << kRtShift) | encoded_offset;
     Emit(encoding);
   }
 

assembler_arm64_test.cc

@@ -1008,15 +1008,22 @@ ASSEMBLER_TEST_RUN(CmpBranchIfNotZeroNotTaken, test) {
   EXPECT_EQ(42, EXECUTE_TEST_CODE_INT64(Int64Return, test->entry()));
 }
 
+static const int64_t kBits5And35 = (1 << 5) | (1ll << 35);
+
 ASSEMBLER_TEST_GENERATE(TstBranchIfZero, assembler) {
-  Label l;
+  Label l, l2;
 
   __ movz(R0, Immediate(42), 0);
-  __ movz(R1, Immediate((0 << 5) | 1), 0);
+  __ LoadImmediate(R1, ~kBits5And35);
 
   __ tbz(&l, R1, 5);
   __ movz(R0, Immediate(0), 0);
   __ Bind(&l);
+
+  __ tbz(&l2, R1, 35);
+  __ movz(R0, Immediate(0), 0);
+  __ Bind(&l2);
+
   __ ret();
 }
 
@@ -1029,7 +1036,7 @@ ASSEMBLER_TEST_GENERATE(TstBranchIfZeroNotTaken, assembler) {
   Label l;
 
   __ movz(R0, Immediate(0), 0);
-  __ movz(R1, Immediate((1 << 5) | 1), 0);
+  __ LoadImmediate(R1, kBits5And35);
 
   __ tbz(&l, R1, 5);
   __ movz(R0, Immediate(42), 0);
@@ -1043,14 +1050,19 @@ ASSEMBLER_TEST_RUN(TstBranchIfZeroNotTaken, test) {
 }
 
 ASSEMBLER_TEST_GENERATE(TstBranchIfNotZero, assembler) {
-  Label l;
+  Label l, l2;
 
   __ movz(R0, Immediate(42), 0);
-  __ movz(R1, Immediate((1 << 5) | 1), 0);
+  __ LoadImmediate(R1, kBits5And35);
 
   __ tbnz(&l, R1, 5);
   __ movz(R0, Immediate(0), 0);
   __ Bind(&l);
+
+  __ tbnz(&l2, R1, 35);
+  __ movz(R0, Immediate(0), 0);
+  __ Bind(&l2);
+
   __ ret();
 }
 
@@ -1063,7 +1075,7 @@ ASSEMBLER_TEST_GENERATE(TstBranchIfNotZeroNotTaken, assembler) {
   Label l;
 
   __ movz(R0, Immediate(0), 0);
-  __ movz(R1, Immediate((0 << 5) | 1), 0);
+  __ LoadImmediate(R1, ~kBits5And35);
 
   __ tbnz(&l, R1, 5);
   __ movz(R0, Immediate(42), 0);
@@ -1080,7 +1092,7 @@ ASSEMBLER_TEST_GENERATE(TstBranchIfZeroFar, assembler) {
   Label l;
 
   __ movz(R0, Immediate(42), 0);
-  __ movz(R1, Immediate((0 << 5) | 1), 0);
+  __ LoadImmediate(R1, ~kBits5And35);
 
   __ tbz(&l, R1, 5);
 
@@ -1103,7 +1115,7 @@ ASSEMBLER_TEST_GENERATE(TstBranchIfNotZeroFar, assembler) {
   Label l;
 
   __ movz(R0, Immediate(42), 0);
-  __ movz(R1, Immediate((1 << 5) | 1), 0);
+  __ LoadImmediate(R1, kBits5And35);
 
   __ tbnz(&l, R1, 5);
 

disassembler_arm64.cc

@@ -358,7 +358,7 @@ int ARM64Decoder::FormatOption(Instr* instr, const char* format) {
         return 6;
       } else {
         ASSERT(STRING_STARTS_WITH(format, "bitpos"));
-        int bitpos = instr->Bits(19, 4) | (instr->Bit(31) << 5);
+        int bitpos = instr->Bits(19, 5) | (instr->Bit(31) << 5);
         buffer_pos_ +=
             Utils::SNPrint(current_position_in_buffer(),
                            remaining_size_in_buffer(), "#%d", bitpos);