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Clarify the expected size/packing of bit fields in stack structures

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While packing is not guaranteed, and most compilers will combine
adjacent bit fields regardless of the alignment requirements of the
datatype that is being divided, here we can be clearer that we
expect packing into 16-bit fields and we do not require (and must not
have) 32-bit alignment of the collections of bitfields.
This commit is contained in:
Nick Briggs
2024-03-07 09:30:59 -08:00
parent fb579a2ab5
commit 55591557b6
1 changed files with 51 additions and 51 deletions
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102
inc/stack.h
View File

@@ -79,22 +79,22 @@ typedef struct fnhead {
} FNHEAD;
typedef struct frameex1 {
unsigned flags : 3;
unsigned fast : 1;
unsigned nil2 : 1; /* not used, prev: This frame treats N-func */
unsigned incall : 1;
unsigned validnametable : 1;
unsigned short flags : 3;
unsigned short fast : 1;
unsigned short nil2 : 1; /* not used, prev: This frame treats N-func */
unsigned short incall : 1;
unsigned short validnametable : 1;
/* 0: look for FunctionHeader
1: look for NameTable on this FrameEx */
unsigned nopush : 1;
unsigned usecount : 8;
unsigned short nopush : 1;
unsigned short usecount : 8;
DLword alink; /* alink pointer (Low addr) */
#ifdef BIGVM
LispPTR fnheader; /* pointer to FunctionHeader (Hi2 addr) */
#else
DLword lofnheader; /* pointer to FunctionHeader (Low addr) */
unsigned hi1fnheader : 8; /* pointer to FunctionHeader (Hi1 addr) */
unsigned hi2fnheader : 8; /* pointer to FunctionHeader (Hi2 addr) */
unsigned short hi1fnheader : 8; /* pointer to FunctionHeader (Hi1 addr) */
unsigned short hi2fnheader : 8; /* pointer to FunctionHeader (Hi2 addr) */
#endif /* BIGVM */
DLword nextblock; /* pointer to FreeStackBlock */
DLword pc; /* Program counter */
@@ -102,23 +102,23 @@ typedef struct frameex1 {
LispPTR nametable; /* ptr to NameTable of this FrameEx (Hi2 addr) */
#else
DLword lonametable; /* ptr to NameTable of this FrameEx (Low addr) */
unsigned hi1nametable : 8; /* ptr to NameTable of this FrameEx (Hi1 addr) */
unsigned hi2nametable : 8; /* ptr to NameTable of this FrameEx (Hi2 addr) */
unsigned short hi1nametable : 8; /* ptr to NameTable of this FrameEx (Hi1 addr) */
unsigned short hi2nametable : 8; /* ptr to NameTable of this FrameEx (Hi2 addr) */
#endif /* BIGVM */
DLword blink; /* blink pointer (Low addr) */
DLword clink; /* clink pointer (Low addr) */
} FX;
typedef struct frameex2 {
unsigned flags : 3;
unsigned fast : 1;
unsigned nil2 : 1; /* not used, prev: This frame treats N-func */
unsigned incall : 1;
unsigned validnametable : 1;
unsigned short flags : 3;
unsigned short fast : 1;
unsigned short nil2 : 1; /* not used, prev: This frame treats N-func */
unsigned short incall : 1;
unsigned short validnametable : 1;
/* 0: look for FunctionHeader
1: look for NameTable on this FrameEx */
unsigned nopush : 1;
unsigned usecount : 8;
unsigned short nopush : 1;
unsigned short usecount : 8;
DLword alink; /* alink pointer (Low addr) */
LispPTR fnheader; /* pointer to FunctionHeader */
DLword nextblock; /* pointer to FreeStackBlock */
@@ -135,11 +135,11 @@ typedef struct fxblock {
} FXBLOCK;
typedef struct basic_frame {
unsigned flags : 3;
unsigned nil : 3;
unsigned residual : 1;
unsigned padding : 1;
unsigned usecnt : 8;
unsigned short flags : 3;
unsigned short nil : 3;
unsigned short residual : 1;
unsigned short padding : 1;
unsigned short usecnt : 8;
DLword ivar; /* stk offset of IVARs for this frame ?? */
} Bframe;
@@ -185,33 +185,33 @@ typedef struct fnhead {
unsigned nil3 : 2; /* not used */
unsigned nil2 : 2; /* not used */
#endif /* BIGVM */
unsigned argtype : 2; /* ?? */
unsigned byteswapped : 1; /* code was reswapped. */
unsigned nil4 : 1; /* not used, prev: native translated? */
unsigned fvaroffset : 8;
unsigned short argtype : 2; /* ?? */
unsigned short byteswapped : 1; /* code was reswapped. */
unsigned short nil4 : 1; /* not used, prev: native translated? */
unsigned short fvaroffset : 8;
/* DLword offset from head of NameTable */
unsigned nlocals : 8; /* ?? */
unsigned short nlocals : 8; /* ?? */
DLword ntsize; /* size of NameTable */
/* NameTable of variable length is following with this structure. */
} FNHEAD;
typedef struct frameex1 {
DLword alink; /* alink pointer (Low addr) */
unsigned usecount : 8;
unsigned nopush : 1;
unsigned validnametable : 1;
unsigned short usecount : 8;
unsigned short nopush : 1;
unsigned short validnametable : 1;
/* 0: look for FunctionHeader
1: look for NameTable on this FrameEx */
unsigned incall : 1;
unsigned nil2 : 1; /* not used, prev: This frame treats N-func */
unsigned fast : 1;
unsigned flags : 3; /* hi word */
unsigned short incall : 1;
unsigned short nil2 : 1; /* not used, prev: This frame treats N-func */
unsigned short fast : 1;
unsigned short flags : 3; /* hi word */
#ifdef BIGVM
LispPTR fnheader; /* pointer to FunctionHeader (Hi2 addr) */
#else
unsigned hi2fnheader : 8; /* pointer to FunctionHeader (Hi2 addr) */
unsigned hi1fnheader : 8; /* pointer to FunctionHeader (Hi1 addr) */
unsigned short hi2fnheader : 8; /* pointer to FunctionHeader (Hi2 addr) */
unsigned short hi1fnheader : 8; /* pointer to FunctionHeader (Hi1 addr) */
DLword lofnheader; /* pointer to FunctionHeader (Low addr) */
#endif /* BIGVM */
@@ -221,8 +221,8 @@ typedef struct frameex1 {
#ifdef BIGVM
LispPTR nametable; /* pointer to NameTable of this FX (Hi2 addr) */
#else
unsigned hi2nametable : 8; /* pointer to NameTable of this FX (Hi2 addr) */
unsigned hi1nametable : 8; /* pointer to NameTable of this FX (Hi1 addr) */
unsigned short hi2nametable : 8; /* pointer to NameTable of this FX (Hi2 addr) */
unsigned short hi1nametable : 8; /* pointer to NameTable of this FX (Hi1 addr) */
DLword lonametable; /* pointer to NameTable of this FX (Low addr) */
#endif /* BIGVM */
@@ -232,15 +232,15 @@ typedef struct frameex1 {
typedef struct frameex2 {
DLword alink; /* alink pointer (Low addr) */
unsigned usecount : 8;
unsigned nopush : 1;
unsigned validnametable : 1;
unsigned short usecount : 8;
unsigned short nopush : 1;
unsigned short validnametable : 1;
/* 0: look for FunctionHeader
1: look for NameTable on this FrameEx */
unsigned incall : 1;
unsigned nil2 : 1; /* not used, prev: This frame treats N-func */
unsigned fast : 1;
unsigned flags : 3;
unsigned short incall : 1;
unsigned short nil2 : 1; /* not used, prev: This frame treats N-func */
unsigned short fast : 1;
unsigned short flags : 3;
LispPTR fnheader; /* pointer to FunctionHeader (swapped) */
@@ -261,11 +261,11 @@ typedef struct fxblock {
typedef struct basic_frame {
DLword ivar;
unsigned usecnt : 8;
unsigned padding : 1;
unsigned residual : 1;
unsigned nil : 3;
unsigned flags : 3;
unsigned short usecnt : 8;
unsigned short padding : 1;
unsigned short residual : 1;
unsigned short nil : 3;
unsigned short flags : 3;
} Bframe;