Implement loop for global regexps in regexp assembler.

src/ia32/regexp-macro-assembler-ia32.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
@@ skipping 42 matching lines @@
  *
  * The registers eax and ebx are free to use for computations.
  *
  * Each call to a public method should retain this convention.
  * The stack will have the following structure:
  *       - Isolate* isolate     (Address of the current isolate)
  *       - direct_call          (if 1, direct call from JavaScript code, if 0
  *                               call through the runtime system)
  *       - stack_area_base      (High end of the memory area to use as
  *                               backtracking stack)
+ *       - capture array size   (may fit multiple sets of matches)
  *       - int* capture_array   (int[num_saved_registers_], for output).
  *       - end of input         (Address of end of string)
  *       - start of input       (Address of first character in string)
  *       - start index          (character index of start)
  *       - String* input_string (location of a handle containing the string)
  *       --- frame alignment (if applicable) ---
  *       - return address
  * ebp-> - old ebp
  *       - backup of caller esi
  *       - backup of caller edi
  *       - backup of caller ebx
+ *       - success counter      (only useful for global regexp to count matches)
  *       - Offset of location before start of input (effectively character
  *         position -1). Used to initialize capture registers to a non-position.
  *       - register 0  ebp[-4]  (Only positions must be stored in the first
  *       - register 1  ebp[-8]   num_saved_registers_ registers)
  *       - ...
  *
  * The first num_saved_registers_ registers are initialized to point to
  * "character -1" in the string (i.e., char_size() bytes before the first
  * character of the string). The remaining registers starts out as garbage.
  *
@@ skipping 614 matching lines @@
     return true;
   }
   // No custom implementation (yet): s(UC16), S(UC16).
   default:
     return false;
   }
 }
 
 
 void RegExpMacroAssemblerIA32::Fail() {
-  ASSERT(FAILURE == 0);  // Return value for failure is zero.
-  __ Set(eax, Immediate(0));
+  STATIC_ASSERT(FAILURE == 0);  // Return value for failure is zero.
+  if (!global()) {
+    __ Set(eax, Immediate(FAILURE));
+  }
   __ jmp(&exit_label_);
 }
 
 
 Handle<HeapObject> RegExpMacroAssemblerIA32::GetCode(Handle<String> source) {
+  Label return_eax, restart;
   // Finalize code - write the entry point code now we know how many
   // registers we need.
 
   // Entry code:
   __ bind(&entry_label_);
 
   // Tell the system that we have a stack frame.  Because the type is MANUAL, no
   // code is generated.
   FrameScope scope(masm_, StackFrame::MANUAL);
 
   // Actually emit code to start a new stack frame.
   __ push(ebp);
   __ mov(ebp, esp);
   // Save callee-save registers. Order here should correspond to order of
   // kBackup_ebx etc.
   __ push(esi);
   __ push(edi);
   __ push(ebx);  // Callee-save on MacOS.
+  __ push(Immediate(0));  // Number of successful matches in a global regexp.
   __ push(Immediate(0));  // Make room for "input start - 1" constant.
 
   // Check if we have space on the stack for registers.
   Label stack_limit_hit;
   Label stack_ok;
 
   ExternalReference stack_limit =
       ExternalReference::address_of_stack_limit(masm_->isolate());
   __ mov(ecx, esp);
   __ sub(ecx, Operand::StaticVariable(stack_limit));
   // Handle it if the stack pointer is already below the stack limit.
   __ j(below_equal, &stack_limit_hit);
   // Check if there is room for the variable number of registers above
   // the stack limit.
   __ cmp(ecx, num_registers_ * kPointerSize);
   __ j(above_equal, &stack_ok);
   // Exit with OutOfMemory exception. There is not enough space on the stack
   // for our working registers.
   __ mov(eax, EXCEPTION);
-  __ jmp(&exit_label_);
+  __ jmp(&return_eax);
 
   __ bind(&stack_limit_hit);
   CallCheckStackGuardState(ebx);
   __ or_(eax, eax);
   // If returned value is non-zero, we exit with the returned value as result.
-  __ j(not_zero, &exit_label_);
+  __ j(not_zero, &return_eax);
 
   __ bind(&stack_ok);
   // Load start index for later use.
   __ mov(ebx, Operand(ebp, kStartIndex));
 
   // Allocate space on stack for registers.
   __ sub(esp, Immediate(num_registers_ * kPointerSize));
   // Load string length.
   __ mov(esi, Operand(ebp, kInputEnd));
   // Load input position.
   __ mov(edi, Operand(ebp, kInputStart));
   // Set up edi to be negative offset from string end.
   __ sub(edi, esi);
 
   // Set eax to address of char before start of the string.
   // (effectively string position -1).
   __ neg(ebx);
   if (mode_ == UC16) {
     __ lea(eax, Operand(edi, ebx, times_2, -char_size()));
   } else {
     __ lea(eax, Operand(edi, ebx, times_1, -char_size()));
   }
   // Store this value in a local variable, for use when clearing
   // position registers.
   __ mov(Operand(ebp, kInputStartMinusOne), eax);
 
+  // Load previous char as initial value of current-character.
+  Label at_start, character_loaded;
+  __ cmp(Operand(ebp, kStartIndex), Immediate(0));
+  __ j(equal, &at_start, Label::kNear);
+  LoadCurrentCharacterUnchecked(-1, 1);  // Load previous char.
+  __ jmp(&character_loaded, Label::kNear);
+  __ bind(&at_start);
+  __ mov(current_character(), '\n');
+
+  if (global()) {
+    // Initializing current-character already done, so skip it.
+    __ jmp(&character_loaded, Label::kNear);
+    // Restart matching from here in a global regexp.
+    __ bind(&restart);
+    // In a restarted pass, initialize current-character here.
+    LoadCurrentCharacterUnchecked(-1, 1);
+  }
+  __ bind(&character_loaded);
+
+  // Initialize on-stack registers.
   if (num_saved_registers_ > 0) {  // Always is, if generated from a regexp.
     // Fill saved registers with initial value = start offset - 1
     // Fill in stack push order, to avoid accessing across an unwritten
     // page (a problem on Windows).
-    __ mov(ecx, kRegisterZero);
-    Label init_loop;
-    __ bind(&init_loop);
-    __ mov(Operand(ebp, ecx, times_1, +0), eax);
-    __ sub(ecx, Immediate(kPointerSize));
-    __ cmp(ecx, kRegisterZero - num_saved_registers_ * kPointerSize);
-    __ j(greater, &init_loop);
+    if (num_saved_registers_ > 8) {
+      __ mov(ecx, kRegisterZero);
+      Label init_loop;
+      __ bind(&init_loop);
+      __ mov(Operand(ebp, ecx, times_1, 0), eax);
+      __ sub(ecx, Immediate(kPointerSize));
+      __ cmp(ecx, kRegisterZero - num_saved_registers_ * kPointerSize);
+      __ j(greater, &init_loop);
+    } else {  // Unroll the loop.
+      for (int i = 0; i < num_saved_registers_; i++) {
+        __ mov(register_location(i), eax);
+      }
+    }
   }
-  // Ensure that we have written to each stack page, in order. Skipping a page
-  // on Windows can cause segmentation faults. Assuming page size is 4k.
-  const int kPageSize = 4096;
-  const int kRegistersPerPage = kPageSize / kPointerSize;
-  for (int i = num_saved_registers_ + kRegistersPerPage - 1;
-      i < num_registers_;
-      i += kRegistersPerPage) {
-    __ mov(register_location(i), eax);  // One write every page.
-  }
-
 
   // Initialize backtrack stack pointer.
   __ mov(backtrack_stackpointer(), Operand(ebp, kStackHighEnd));
-  // Load previous char as initial value of current-character.
-  Label at_start;
-  __ cmp(Operand(ebp, kStartIndex), Immediate(0));
-  __ j(equal, &at_start);
-  LoadCurrentCharacterUnchecked(-1, 1);  // Load previous char.
+
   __ jmp(&start_label_);
-  __ bind(&at_start);
-  __ mov(current_character(), '\n');
-  __ jmp(&start_label_);
-
 
   // Exit code:
   if (success_label_.is_linked()) {
     // Save captures when successful.
     __ bind(&success_label_);
     if (num_saved_registers_ > 0) {
       // copy captures to output
       __ mov(ebx, Operand(ebp, kRegisterOutput));
       __ mov(ecx, Operand(ebp, kInputEnd));
       __ mov(edx, Operand(ebp, kStartIndex));
       __ sub(ecx, Operand(ebp, kInputStart));
       if (mode_ == UC16) {
         __ lea(ecx, Operand(ecx, edx, times_2, 0));
       } else {
         __ add(ecx, edx);
       }
       for (int i = 0; i < num_saved_registers_; i++) {
         __ mov(eax, register_location(i));
+        if (i == 0 && global()) {
+          // Keep capture start in edx for the zero-length check later.
+          __ mov(edx, eax);
+        }
         // Convert to index from start of string, not end.
         __ add(eax, ecx);
         if (mode_ == UC16) {
           __ sar(eax, 1);  // Convert byte index to character index.
         }
         __ mov(Operand(ebx, i * kPointerSize), eax);
       }
     }
-    __ mov(eax, Immediate(SUCCESS));
+
+    if (global()) {
+    // Restart matching if the regular expression is flagged as global.
+      // Increment success counter.
+      __ inc(Operand(ebp, kSuccessfulCaptures));
+      // Capture results have been stored, so the number of remaining global
+      // output registers is reduced by the number of stored captures.
+      __ mov(ecx, Operand(ebp, kNumOutputRegisters));
+      __ sub(ecx, Immediate(num_saved_registers_));
+      // Check whether we have enough room for another set of capture results.
+      __ cmp(ecx, Immediate(num_saved_registers_));
+      __ j(less, &exit_label_);
+
+      __ mov(Operand(ebp, kNumOutputRegisters), ecx);
+      // Advance the location for output.
+      __ add(Operand(ebp, kRegisterOutput),
+             Immediate(num_saved_registers_ * kPointerSize));
+
+      // Prepare eax to initialize registers with its value in the next run.
+      __ mov(eax, Operand(ebp, kInputStartMinusOne));
+
+      // Special case for zero-length matches.
+      // edx: capture start index
+      __ cmp(edi, edx);
+      // Not a zero-length match, restart.
+      __ j(not_equal, &restart);
+      // edi (offset from the end) is zero if we already reached the end.
+      __ test(edi, edi);
+      __ j(zero, &exit_label_, Label::kNear);
+      // Advance current position after a zero-length match.
+      if (mode_ == UC16) {
+        __ add(edi, Immediate(2));
+      } else {
+        __ inc(edi);
+      }
+      __ jmp(&restart);
+    } else {
+      __ mov(eax, Immediate(SUCCESS));
+    }
   }
-  // Exit and return eax
+
   __ bind(&exit_label_);
+  if (global()) {
+    // Return the number of successful captures.
+    __ mov(eax, Operand(ebp, kSuccessfulCaptures));
+  }
+
+  __ bind(&return_eax);
   // Skip esp past regexp registers.
   __ lea(esp, Operand(ebp, kBackup_ebx));
   // Restore callee-save registers.
   __ pop(ebx);
   __ pop(edi);
   __ pop(esi);
   // Exit function frame, restore previous one.
   __ pop(ebp);
   __ ret(0);
 
   // Backtrack code (branch target for conditional backtracks).
   if (backtrack_label_.is_linked()) {
     __ bind(&backtrack_label_);
     Backtrack();
   }
 
   Label exit_with_exception;
 
   // Preempt-code
   if (check_preempt_label_.is_linked()) {
     SafeCallTarget(&check_preempt_label_);
 
     __ push(backtrack_stackpointer());
     __ push(edi);
 
     CallCheckStackGuardState(ebx);
     __ or_(eax, eax);
     // If returning non-zero, we should end execution with the given
     // result as return value.
-    __ j(not_zero, &exit_label_);
+    __ j(not_zero, &return_eax);
 
     __ pop(edi);
     __ pop(backtrack_stackpointer());
     // String might have moved: Reload esi from frame.
     __ mov(esi, Operand(ebp, kInputEnd));
     SafeReturn();
   }
 
   // Backtrack stack overflow code.
   if (stack_overflow_label_.is_linked()) {
@@ skipping 26 matching lines @@
     __ pop(edi);
     __ pop(esi);
     SafeReturn();
   }
 
   if (exit_with_exception.is_linked()) {
     // If any of the code above needed to exit with an exception.
     __ bind(&exit_with_exception);
     // Exit with Result EXCEPTION(-1) to signal thrown exception.
     __ mov(eax, EXCEPTION);
-    __ jmp(&exit_label_);
+    __ jmp(&return_eax);
   }
 
   CodeDesc code_desc;
   masm_->GetCode(&code_desc);
   Handle<Code> code =
       masm_->isolate()->factory()->NewCode(code_desc,
                                            Code::ComputeFlags(Code::REGEXP),
                                            masm_->CodeObject());
   PROFILE(masm_->isolate(), RegExpCodeCreateEvent(*code, *source));
   return Handle<HeapObject>::cast(code);
@@ skipping 390 matching lines @@
 }
 
 
 #undef __
 
 #endif  // V8_INTERPRETED_REGEXP
 
 }}  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32