[wasm] Implementation of Word32PairShr and Word32PairSar on arm.

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index f99f239d6f94cbb496a65234b6fd2fc6274e305d..b3c1f73869455adf92fb8958f5bdb3fa9b4934ad 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -1148,6 +1148,99 @@ void MacroAssembler::LslPair(Register dst_low, Register dst_high,
   }
 }
 
+void MacroAssembler::LsrPair(Register dst_low, Register dst_high,
+                             Register src_low, Register src_high,
+                             Register scratch, Register shift) {
+  DCHECK(!AreAliased(dst_low, src_high));
+  DCHECK(!AreAliased(dst_low, shift));
+
+  Label less_than_32;
+  Label done;
+  rsb(scratch, shift, Operand(32), SetCC);
+  b(gt, &less_than_32);
+  // If shift >= 32
+  and_(scratch, shift, Operand(0x1f));
+  lsr(dst_low, src_high, Operand(scratch));
+  mov(dst_high, Operand(0));
+  jmp(&done);
+  bind(&less_than_32);
+  // If shift < 32
+

[Rodolph Perfetta (ARM), 2016/03/11 15:00:42]

nit: did you intended the blank line?

+  lsr(dst_low, src_low, Operand(shift));
+  orr(dst_low, dst_low, Operand(src_high, LSL, scratch));
+  lsr(dst_high, src_high, Operand(shift));
+  bind(&done);
+}
+
+void MacroAssembler::LsrPair(Register dst_low, Register dst_high,
+                             Register src_low, Register src_high,
+                             uint32_t shift) {
+  DCHECK(!AreAliased(dst_low, src_high));
+  Label less_than_32;
+  Label done;
+  if (shift == 32) {
+    mov(dst_low, src_high);
+    mov(dst_high, Operand(0));
+  } else if (shift > 32) {
+    shift &= 0x1f;
+    lsr(dst_low, src_high, Operand(shift));
+    mov(dst_high, Operand(0));
+  } else if (shift == 0) {
+    Move(dst_low, src_low);
+    Move(dst_high, src_high);
+  } else {
+    lsr(dst_low, src_low, Operand(shift));
+    orr(dst_low, dst_low, Operand(src_high, LSL, 32 - shift));
+    lsr(dst_high, src_high, Operand(shift));
+  }
+}
+
+void MacroAssembler::AsrPair(Register dst_low, Register dst_high,
+                             Register src_low, Register src_high,
+                             Register scratch, Register shift) {
+  DCHECK(!AreAliased(dst_low, src_high));
+  DCHECK(!AreAliased(dst_low, shift));
+
+  Label less_than_32;
+  Label done;
+  rsb(scratch, shift, Operand(32), SetCC);
+  b(gt, &less_than_32);
+  // If shift >= 32
+  and_(scratch, shift, Operand(0x1f));
+  asr(dst_low, src_high, Operand(scratch));
+  asr(dst_high, src_high, Operand(31));
+  jmp(&done);
+  bind(&less_than_32);
+  // If shift < 32
+  lsr(dst_low, src_low, Operand(shift));
+  orr(dst_low, dst_low, Operand(src_high, LSL, scratch));
+  asr(dst_high, src_high, Operand(shift));
+  bind(&done);
+}
+
+void MacroAssembler::AsrPair(Register dst_low, Register dst_high,
+                             Register src_low, Register src_high,
+                             uint32_t shift) {
+  DCHECK(!AreAliased(dst_low, src_high));
+  Label less_than_32;
+  Label done;
+  if (shift == 32) {
+    mov(dst_low, src_high);
+    asr(dst_high, src_high, Operand(31));
+  } else if (shift > 32) {
+    shift &= 0x1f;
+    asr(dst_low, src_high, Operand(shift));
+    asr(dst_high, src_high, Operand(31));
+  } else if (shift == 0) {
+    Move(dst_low, src_low);
+    Move(dst_high, src_high);
+  } else {
+    lsr(dst_low, src_low, Operand(shift));
+    orr(dst_low, dst_low, Operand(src_high, LSL, 32 - shift));
+    asr(dst_high, src_high, Operand(shift));
+  }
+}
+
 void MacroAssembler::LoadConstantPoolPointerRegisterFromCodeTargetAddress(
     Register code_target_address) {
   DCHECK(FLAG_enable_embedded_constant_pool);