added top element size computation information
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3 changed files with 114 additions and 47 deletions
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@ -49,7 +49,7 @@ occam.X:
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cd occam; make "PIC="$(PIC) "TBL="$(TBL) "EQN="$(EQN) "TARGET="$(TARGET)
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ego.doc: ego.X
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ego.X:
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cd ego; make "REFER="$(REFER) "TARGET="$(TARGET)
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cd ego; make "REFER="$(REFER) "TARGET="$(TARGET) "TBL="$(TBL)
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em.$(SUF): em.X
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em.X:
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cd em; make "TBL="$(TBL) "NROFF="$(NROFF) "SUF="$(SUF) "TARGET="$(TARGET)
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@ -98,8 +98,8 @@ Truncation is always to the nearest floating-point number that can
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be represented.
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.NS A.6.3.7
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.IP -
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The type returned by the sizeof-operator is 'unsigned int'. This is done
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for backward compatibility reasons.
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The type returned by the sizeof-operator (also known as size_t)
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is 'unsigned int'. This is done for backward compatibility reasons.
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.IP -
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Casting an integer to a pointer or vice versa has no effect in
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bit-pattern when the sizes are equal. Otherwise the value will be
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87
doc/ncg.doc
87
doc/ncg.doc
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@ -301,16 +301,17 @@ Here is a list of reserved words; all of these are unavailable as identifiers.
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.TS
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box;
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l l l l l.
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ADDR STACK from proc sfit
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COERCIONS STACKINGRULES gen reg_any test
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INSTRUCTIONS TESTS highw reg_float to
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INT TIMEFACTOR inreg reg_loop ufit
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MOVES TOKENS is_rom reg_pointer uses
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PATTERNS call kills regvar with
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PROPERTIES cost leaving return yields
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REGISTERS defined loww reusing
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SETS exact move rom
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SIZEFACTOR example pat samesign
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ADDR STACKINGRULES gen proc test
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COERCIONS TESTS highw reg_any to
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INSTRUCTIONS TIMEFACTOR inreg reg_float topeltsize
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INT TOKENS is_rom reg_loop ufit
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MOVES call kills reg_pointer uses
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PATTERNS cost lab regvar with
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PROPERTIES defined labeldef return yields
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REGISTERS exact leaving reusing
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SETS example loww rom
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SIZEFACTOR fallthrough move samesign
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STACK from pat sfit
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.TE
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C style comments are accepted.
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.DS
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@ -928,6 +929,17 @@ If
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.I t
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is omitted reg_any is assumed.
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Undefined if inreg(\fIe\fP)<=0 .
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.LP
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The next two `functions' are only needed in a table that
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uses the top element size information.
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.IP topeltsize($a) 16
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Returns the size of the element on top of the EM-stack at the label
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identified by $a. This can be used to put the top of the stack in a
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register at the moment of an unconditional jump. At an unconditional jump,
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the size of the top-element will always look 0.
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.IP fallthrough($a)
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Returns 1 if the label identified by $a can be reached via fallthrough, 0
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otherwise.
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.NH 2
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Token descriptions
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.PP
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@ -1017,6 +1029,13 @@ This rule of three is an unfortunate implementation dependent restriction,
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but patterns longer than three EM instructions are luckily not needed
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too often.
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.PP
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The EM mnemonic may also be the pseudo-instruction \fBlab\fP, which matches
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a label. Its argument can be used in testing on topeltsize and
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fallthrough. When this pattern is specified, the label should be defined
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explicitly with a
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.I labeldef
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statement.
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.PP
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Following the EM-pattern there may be more than one code
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rule,
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.I cg
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@ -1308,6 +1327,16 @@ C-routine
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Explanation of this must wait for the description of the
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file mach.c below.
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.IP 5)
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The
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.I labeldef
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statement. Its only argument should be that of the
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.I lab
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pseudo-instruction. This is needed to generate local labels when the
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top element size information is used. It takes the form
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.DS
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labeldef $i
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.DE
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.IP 6)
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A temporary label of the form <digit>: may be placed here.
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Expressions of the form [0-9][bf] in this code rule
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generate the same string as is used for this label.
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@ -1552,6 +1581,35 @@ A simple jump.
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The stack pattern guarantees that everything will be stacked
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before the jump is taken.
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.DS
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pat lab topeltsize($1)==2 && !fallthrough($1)
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gen labeldef $1 yields r0
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pat lab topeltsize($1)==2 && fallthrough($1)
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with src2
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gen move %1,r0
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labeldef $1 yields r0
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pat lab topeltsize($1)!=2
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with STACK
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kills all
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gen labeldef $1
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pat bra topeltsize($1)==2
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with src2 STACK
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gen move %1,d0
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jbr {label, $1}
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pat bra topeltsize($1)!=2
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with STACK
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gen jbr {label, $1}
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.DE
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The combination of these patterns make sure that the top of the EM-stack will
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be in register r0 whenever necessary. The top element size mechanism will
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also show a size of 0 whenever a conditional branch to a label
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occurs. This saves a lot of patterns and hardly decreases performance.
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When the same register is used to return function results, this can save
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many moves to and from the stack.
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.DS
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.ta 7.5c
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pat cal
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with STACK
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@ -2738,6 +2796,11 @@ DO_RETURN
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Returns from this level of codegen().
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Is used at the end of coercions,
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move rules etc..
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.NH 4
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DO_LABDEF
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.PP
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This prints a label when the top element size mechanism is used. Only done on
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toplevel.
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.NH 3
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compute.c
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.PP
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@ -2803,6 +2866,10 @@ This module maintains a list of global symbols that have a
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pseudo associated.
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There are functions to enter a symbol and to find a symbol.
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.NH 3
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label.c
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.PP
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This module contains routines to handle the top element size messages.
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.NH 3
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main.c
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.PP
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Main routine of the code generator.
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