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Diffstat (limited to 'gcc-4.2.1/gcc/ada/s-stausa.ads')
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diff --git a/gcc-4.2.1/gcc/ada/s-stausa.ads b/gcc-4.2.1/gcc/ada/s-stausa.ads new file mode 100644 index 000000000..72242c206 --- /dev/null +++ b/gcc-4.2.1/gcc/ada/s-stausa.ads @@ -0,0 +1,343 @@ +------------------------------------------------------------------------------ +-- -- +-- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS -- +-- -- +-- S Y S T E M - S T A C K _ U S A G E -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 2004-2005, Free Software Foundation, Inc. -- +-- -- +-- GNARL is free software; you can redistribute it and/or modify it under -- +-- terms of the GNU General Public License as published by the Free Soft- -- +-- ware Foundation; either version 2, or (at your option) any later ver- -- +-- sion. GNARL is distributed in the hope that it will be useful, but WITH- -- +-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- +-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- +-- for more details. You should have received a copy of the GNU General -- +-- Public License distributed with GNARL; see file COPYING. If not, write -- +-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- +-- Boston, MA 02110-1301, USA. -- +-- -- +-- As a special exception, if other files instantiate generics from this -- +-- unit, or you link this unit with other files to produce an executable, -- +-- this unit does not by itself cause the resulting executable to be -- +-- covered by the GNU General Public License. This exception does not -- +-- however invalidate any other reasons why the executable file might be -- +-- covered by the GNU Public License. -- +-- -- +-- GNARL was developed by the GNARL team at Florida State University. -- +-- Extensive contributions were provided by Ada Core Technologies, Inc. -- +-- -- +------------------------------------------------------------------------------ + +with System; +with System.Storage_Elements; +with System.Address_To_Access_Conversions; + +package System.Stack_Usage is + pragma Preelaborate; + + package SSE renames System.Storage_Elements; + + Byte_Size : constant := 8; + Word_32_Size : constant := 4 * Byte_Size; + + type Word_32 is mod 2 ** Word_32_Size; + for Word_32'Alignment use 4; + + subtype Stack_Address is SSE.Integer_Address; + -- Address on the stack + -- + -- Note: in this package, when comparing two addresses on the stack, the + -- comments use the terms "outer", "inner", "outermost" and "innermost" + -- instead of the ambigous "higher", "lower", "highest" and "lowest". + -- "inner" means "closer to the bottom of stack" and is the contrary of + -- "outer". "innermost" means "closest address to the bottom of stack". The + -- stack is growing from the inner to the outer. + + -- Top/Bottom would be much better than inner and outer ??? + + function To_Stack_Address (Value : System.Address) return Stack_Address + renames System.Storage_Elements.To_Integer; + + type Stack_Analyzer is private; + -- Type of the stack analyzer tool. It is used to fill a portion of + -- the stack with Pattern, and to compute the stack used after some + -- execution. + + -- Usage: + + -- A typical use of the package is something like: + + -- A : Stack_Analyzer; + + -- task T is + -- pragma Storage_Size (A_Storage_Size); + -- end T; + + -- [...] + + -- Bottom_Of_Stack : aliased Integer; + -- -- Bottom_Of_Stack'Address will be used as an approximation of + -- -- the bottom of stack. A good practise is to avoid allocating + -- -- other local variables on this stack, as it would degrade + -- -- the quality of this approximation. + + -- begin + -- Initialize_Analyzer (A, + -- "Task t", + -- A_Storage_Size - A_Guard, + -- To_Stack_Address (Bottom_Of_Stack'Address)); + -- Fill_Stack (A); + -- Some_User_Code; + -- Compute_Result (A); + -- Report_Result (A); + -- end T; + + -- Errors: + -- + -- We are instrumenting the code to measure the stack used by the user + -- code. This method has a number of systematic errors, but several + -- methods can be used to evaluate or reduce those errors. Here are + -- those errors and the strategy that we use to deal with them: + + -- Bottom offset: + + -- Description: The procedure used to fill the stack with a given + -- pattern will itself have a stack frame. The value of the stack + -- pointer in this procedure is, therefore, different from the value + -- before the call to the instrumentation procedure. + + -- Strategy: The user of this package should measure the bottom of stack + -- before the call to Fill_Stack and pass it in parameter. + + -- Instrumentation threshold at writing: + + -- Description: The procedure used to fill the stack with a given + -- pattern will itself have a stack frame. Therefore, it will + -- fill the stack after this stack frame. This part of the stack will + -- appear as used in the final measure. + + -- Strategy: As the user passes the value of the bottom of stack to + -- the instrumentation to deal with the bottom offset error, and as as + -- the instrumentation procedure knows where the pattern filling start + -- on the stack, the difference between the two values is the minimum + -- stack usage that the method can measure. If, when the results are + -- computed, the pattern zone has been left untouched, we conclude + -- that the stack usage is inferior to this minimum stack usage. + + -- Instrumentation threshold at reading: + + -- Description: The procedure used to read the stack at the end of the + -- execution clobbers the stack by allocating its stack frame. If this + -- stack frame is bigger than the total stack used by the user code at + -- this point, it will increase the measured stack size. + + -- Strategy: We could augment this stack frame and see if it changes the + -- measure. However, this error should be negligeable. + + -- Pattern zone overflow: + + -- Description: The stack grows outer than the outermost bound of the + -- pattern zone. In that case, the outermost region modified in the + -- pattern is not the maximum value of the stack pointer during the + -- execution. + + -- Strategy: At the end of the execution, the difference between the + -- outermost memory region modified in the pattern zone and the + -- outermost bound of the pattern zone can be understood as the + -- biggest allocation that the method could have detect, provided + -- that there is no "Untouched allocated zone" error and no "Pattern + -- usage in user code" error. If no object in the user code is likely + -- to have this size, this is not likely to happen. + + -- Pattern usage in user code: + + -- Description: The pattern can be found in the object of the user code. + -- Therefore, the address space where this object has been allocated + -- will appear as untouched. + + -- Strategy: Choose a pattern that is uncommon. 16#0000_0000# is the + -- worst choice; 16#DEAD_BEEF# can be a good one. A good choice is an + -- address which is not a multiple of 2, and which is not in the + -- target address space. You can also change the pattern to see if it + -- changes the measure. Note that this error *very* rarely influence + -- the measure of the total stack usage: to have some influence, the + -- pattern has to be used in the object that has been allocated on the + -- outermost address of the used stack. + + -- Stack overflow: + + -- Description: The pattern zone does not fit on the stack. This may + -- lead to an erroneous execution. + + -- Strategy: Specify a storage size that is bigger than the size of the + -- pattern. 2 times bigger should be enough. + + -- Augmentation of the user stack frames: + + -- Description: The use of instrumentation object or procedure may + -- augment the stack frame of the caller. + + -- Strategy: Do *not* inline the instrumentation procedures. Do *not* + -- allocate the Stack_Analyzer object on the stack. + + -- Untouched allocated zone: + + -- Description: The user code may allocate objects that it will never + -- touch. In that case, the pattern will not be changed. + + -- Strategy: There are no way to detect this error. Fortunately, this + -- error is really rare, and it is most probably a bug in the user + -- code, e.g. some uninitialized variable. It is (most of the time) + -- harmless: it influences the measure only if the untouched allocated + -- zone happens to be located at the outermost value of the stack + -- pointer for the whole execution. + + procedure Initialize (Buffer_Size : Natural); + pragma Export (C, Initialize, "__gnat_stack_usage_initialize"); + -- Initializes the size of the buffer that stores the results. Only the + -- first Buffer_Size results are stored. Any results that do not fit in + -- this buffer will be displayed on the fly. + + procedure Fill_Stack (Analyzer : in out Stack_Analyzer); + -- Fill an area of the stack with the pattern Analyzer.Pattern. The size + -- of this area is Analyzer.Size. After the call to this procedure, + -- the memory will look like that: + -- + -- Stack growing + -- -----------------------------------------------------------------------> + -- |<---------------------->|<----------------------------------->| + -- | Stack frame | Memory filled with Analyzer.Pattern | + -- | of Fill_Stack | | + -- | (deallocated at | | + -- | the end of the call) | | + -- ^ | | + -- Analyzer.Bottom_Of_Stack ^ | + -- Analyzer.Inner_Pattern_Mark ^ + -- Analyzer.Outer_Pattern_Mark + + procedure Initialize_Analyzer + (Analyzer : in out Stack_Analyzer; + Task_Name : String; + Size : Natural; + Bottom : Stack_Address; + Pattern : Word_32 := 16#DEAD_BEEF#); + -- Should be called before any use of a Stack_Analyzer, to initialize it. + -- Size is the size of the pattern zone. Bottom should be a close + -- approximation of the caller base frame address. + + Is_Enabled : Boolean := False; + -- When this flag is true, then stack analysis is enabled + + procedure Compute_Result (Analyzer : in out Stack_Analyzer); + -- Read the patern zone and deduce the stack usage. It should be called + -- from the same frame as Fill_Stack. If Analyzer.Probe is not null, an + -- array of Word_32 with Analyzer.Probe elements is allocated on + -- Compute_Result's stack frame. Probe can be used to detect the error: + -- "instrumentation threshold at reading". See above. After the call + -- to this procedure, the memory will look like: + -- + -- Stack growing + -- -----------------------------------------------------------------------> + -- |<---------------------->|<-------------->|<--------->|<--------->| + -- | Stack frame | Array of | used | Memory | + -- | of Compute_Result | Analyzer.Probe | during | filled | + -- | (deallocated at | elements | the | with | + -- | the end of the call) | | execution | pattern | + -- | ^ | | | + -- | Inner_Pattern_Mark | | | + -- | | | + -- |<----------------------------------------------------> | + -- Stack used ^ + -- Outer_Pattern_Mark + + procedure Report_Result (Analyzer : Stack_Analyzer); + -- Store the results of the computation in memory, at the address + -- corresponding to the symbol __gnat_stack_usage_results. This is not + -- done inside Compute_Resuls in order to use as less stack as possible + -- within a task. + + procedure Output_Results; + -- Print the results computed so far on the standard output. Should be + -- called when all tasks are dead. + + pragma Export (C, Output_Results, "__gnat_stack_usage_output_results"); + +private + + Task_Name_Length : constant := 32; + + package Word_32_Addr is + new System.Address_To_Access_Conversions (Word_32); + + type Stack_Analyzer is record + Task_Name : String (1 .. Task_Name_Length); + -- Name of the task + + Size : Natural; + -- Size of the pattern zone + + Pattern : Word_32; + -- Pattern used to recognize untouched memory + + Inner_Pattern_Mark : Stack_Address; + -- Innermost bound of the pattern area on the stack + + Outer_Pattern_Mark : Stack_Address; + -- Outermost bound of the pattern area on the stack + + Outermost_Touched_Mark : Stack_Address; + -- Outermost address of the pattern area whose value it is pointing + -- at has been modified during execution. If the systematic error are + -- compensated, it is the outermost value of the stack pointer during + -- the execution. + + Bottom_Of_Stack : Stack_Address; + -- Address of the bottom of the stack, as given by the caller of + -- Initialize_Analyzer. + + Array_Address : System.Address; + -- Address of the array of Word_32 that represents the pattern zone + + First_Is_Outermost : Boolean; + -- Set to true if the first element of the array of Word_32 that + -- represents the pattern zone is at the outermost address of the + -- pattern zone; false if it is the innermost address. + + Result_Id : Positive; + -- Id of the result. If less than value given to gnatbind -u corresponds + -- to the location in the result array of result for the current task. + end record; + + Environment_Task_Analyzer : Stack_Analyzer; + + Compute_Environment_Task : Boolean; + + type Task_Result is record + Task_Name : String (1 .. Task_Name_Length); + Measure : Natural; + Max_Size : Natural; + end record; + + type Result_Array_Type is array (Positive range <>) of Task_Result; + type Result_Array_Ptr is access all Result_Array_Type; + + Result_Array : Result_Array_Ptr; + pragma Export (C, Result_Array, "__gnat_stack_usage_results"); + -- Exported in order to have an easy accessible symbol in when debugging + + Next_Id : Positive := 1; + -- Id of the next stack analyzer + + function Stack_Size + (SP_Low : Stack_Address; + SP_High : Stack_Address) return Natural; + pragma Inline (Stack_Size); + -- Return the size of a portion of stack delimeted by SP_High and SP_Low + -- (), i.e. the difference between SP_High and SP_Low. The storage element + -- pointed by SP_Low is not included in the size. Inlined to reduce the + -- size of the stack used by the instrumentation code. + +end System.Stack_Usage; |