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dev:crosscompiler:backend_arm:register_allocation

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dev:crosscompiler:backend_arm:register_allocation [2019/01/24 19:44] – [Locals on the Stack] ursgrafdev:crosscompiler:backend_arm:register_allocation [2019/10/03 10:22] (current) – [Parameter Passing] ursgraf
Line 13: Line 13:
 | R15 | dedicated | PC |    | R15 | dedicated | PC |   
 | D0 | dedicated| scratch register | | D0 | dedicated| scratch register |
-| D1 | volatile 1. parameter, local variables, return value | +| D1 | dedicatedscratch register, return value | 
-| D2-D6 | volatile | further parameters, local variables |+| D2-D6 | volatile | parameters, local variables |
 | D7-D10 | volatile | local variables | | D7-D10 | volatile | local variables |
 | D11-D31 | nonvolatile | local variables | | D11-D31 | nonvolatile | local variables |
Line 32: Line 32:
  
 ===== Parameter Passing ===== ===== Parameter Passing =====
-Parameters are passed in R0..R5 and D1..D6.\\ +Parameters are passed in R0..R5 and D2..D6.\\ 
-In the interface //arm/Registers// you can find the definitions about which registers are used for volatiles and nonvolatiles and which are used for parameter passing. Important: the number of parameter registers must be smaller or equal than the number of volatiles. Due to the interleaving of D and S registers in the extension registers, parameters must be carefully copied into the parameter registers. D1 to D6 hold the parameters regardless of the parameter being of type single or double. To give an example. For method //m1(float a, double b, float c, double d)// the four parameters will be passed as follows: +In the interface //arm/Registers// you can find the definitions about which registers are used for volatiles and nonvolatiles and which are used for parameter passing. Important: the number of parameter registers must be smaller or equal than the number of volatiles. Due to the interleaving of D and S registers in the extension registers, parameters must be carefully copied into the parameter registers. D2 to D6 hold the parameters regardless of the parameter being of type single or double. To give an example. For method //m1(float a, double b, float c, double d)// the four parameters will be passed as follows: 
-|S0|S1|S2|S3|S4|S5|S6|S7|S8|S9| +|S0|S1|S2|S3|S4|S5|S6|S7|S8|S9|S10|S11
-|  D0  ||  D1  ||  D2  ||  D3  ||  D4  || +|  D0  ||  D1  ||  D2  ||  D3  ||  D4  || D5 || 
-|  ^^a| ^  b  ^^c| ^  d  ^^+| ^|  ^^a| ^  b  ^^c| ^  d  ^^ 
 + 
 +If the parameters do not fit into the parameter register, they will be passed on the stack in a special parameter block. Note that the block is filled with parameters of type integer (offset increases with parameter number) first. After this parameters of type float and double are pushed into this block. Parameters of type float and double both occupy 8 bytes. 
  
 ===== Locals on the Stack ===== ===== Locals on the Stack =====
dev/crosscompiler/backend_arm/register_allocation.1548355445.txt.gz · Last modified: 2019/01/24 19:44 by ursgraf