Bug 995230 - Inline Math.clz32 on ARM. r=dougc

js/src/jit/arm/Assembler-arm.cpp

@@ -1550,6 +1550,13 @@ Assembler::as_udiv(Register rd, Register rn, Register rm, Condition c)
     return writeInst(0x0730f010 | c | RN(rd) | RM(rm) | rn.code());
 }
 
+BufferOffset
+Assembler::as_clz(Register dest, Register src, Condition c, Instruction *instdest)
+{
+    return writeInst(RD(dest) | src.code() | c | 0x016f0f10, (uint32_t*)instdest);
+}
+
+
 // Data transfer instructions: ldr, str, ldrb, strb. Using an int to
 // differentiate between 8 bits and 32 bits is overkill, but meh.
 BufferOffset

js/src/jit/arm/Assembler-arm.h

@@ -1193,9 +1193,9 @@ class Assembler : public AssemblerShared
     // exist, when calling with a third dest parameter, a this object is still
     // needed. Dummy always happens to be null, but we shouldn't be looking at
     // it in any case.
+  public:
     static Assembler *Dummy;
 
-  public:
     // For the alignment fill use NOP: 0x0320f000 or (Always | InstNOP::NopInst).
     // For the nopFill use a branch to the next instruction: 0xeaffffff.
     Assembler()
@@ -1370,6 +1370,7 @@ class Assembler : public AssemblerShared
 
     BufferOffset as_sdiv(Register dest, Register num, Register div, Condition c = Always);
     BufferOffset as_udiv(Register dest, Register num, Register div, Condition c = Always);
+    BufferOffset as_clz(Register dest, Register src, Condition c = Always, Instruction *instdest = nullptr);
 
     // Data transfer instructions: ldr, str, ldrb, strb.
     // Using an int to differentiate between 8 bits and 32 bits is overkill.

js/src/jit/arm/CodeGenerator-arm.cpp

@@ -973,6 +973,16 @@ CodeGeneratorARM::visitUrshD(LUrshD *ins)
     return true;
 }
 
+bool
+CodeGeneratorARM::visitClzI(LClzI *ins)
+{
+    Register input = ToRegister(ins->input());
+    Register output = ToRegister(ins->output());
+
+    masm.ma_clz(input, output);
+    return true;
+}
+
 bool
 CodeGeneratorARM::visitPowHalfD(LPowHalfD *ins)
 {

js/src/jit/arm/CodeGenerator-arm.h

@@ -124,6 +124,8 @@ class CodeGeneratorARM : public CodeGeneratorShared
     virtual bool visitShiftI(LShiftI *ins);
     virtual bool visitUrshD(LUrshD *ins);
 
+    virtual bool visitClzI(LClzI *ins);
+
     virtual bool visitTestIAndBranch(LTestIAndBranch *test);
     virtual bool visitCompare(LCompare *comp);
     virtual bool visitCompareAndBranch(LCompareAndBranch *comp);

js/src/jit/arm/MacroAssembler-arm.cpp

@@ -1004,7 +1004,12 @@ MacroAssemblerARM::ma_udiv(Register num, Register div, Register dest, Condition
 {
     as_udiv(dest, num, div, cond);
 }
-
+// Miscelanous instructions
+void
+MacroAssemblerARM::ma_clz(Register src, Register dest, Condition cond)
+{
+    as_clz(dest, src, cond);
+}
 // Memory.
 // Shortcut for when we know we're transferring 32 bits of data.
 void

js/src/jit/arm/MacroAssembler-arm.h

@@ -277,7 +277,8 @@ class MacroAssemblerARM : public Assembler
     // Division - depends on integer divide instructions being supported.
     void ma_sdiv(Register num, Register div, Register dest, Condition cond = Always);
     void ma_udiv(Register num, Register div, Register dest, Condition cond = Always);
-
+    // Misc operations
+    void ma_clz(Register src, Register dest, Condition cond = Always);
     // Memory:
     // Shortcut for when we know we're transferring 32 bits of data.
     void ma_dtr(LoadStore ls, Register rn, Imm32 offset, Register rt,