Thread View: gnu.gcc.bug
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Started by Ian Chou
Sat, 05 Sep 1992 00:29
GNU C Compiler Bug
Author: Ian Chou
Date: Sat, 05 Sep 1992 00:29
Date: Sat, 05 Sep 1992 00:29
254 lines
9675 bytes
9675 bytes
Author: Ian D. Chou
e-mail: ichou@amd-1s.hac.com
Machine type: Auspex Sparc
OS: Unix
gcc version 1.37.1
GNU CPP version 1.37.1
GNU C version 1.37.1 (68k, MIT syntax) compiled by CC.
default target switches: -m68020 -mc68020 -m68881 -mbitfield
Following is a source listing which exhibits a problem when compiling
structures containing bit fields with the -fvolatile option. Following
this is the assembly code generated for this C code. One listing is
with the -fvolatile flag (incorrect), and the last one is without the
flag (correct code).
The -fvolatile flag causes the wrong assembler instruction to be
generated, when the field byteOffset is accessed, only the low order
byte is moved into a register but the upper 24 bits of that same
register is extracted and operated on.
EXAMPLE OF CODE WHICH DOES NOT WORK:
====================================
typedef struct _CharInfo {
unsigned byteOffset:24; /* byte offset of the raster from pGlyphs */
unsigned exists:1; /* true iff glyph exists for this char */
unsigned pad:7; /* must be zero for now */
} CharInfoRec;
typedef struct _FontInfo {
unsigned int version1; /* version stamp */
unsigned int allExist;
unsigned int drawDirection;
unsigned int noOverlap; /* true if:
* max(rightSideBearing-characterWidth)
* <= minbounds->metrics.leftSideBearing
*/
unsigned int constantMetrics;
unsigned int mcgFont; /* AMD44 modification - when set to
* true it indicates that the font is
* approved for loading into Display
* Memory. This field is set true or
* false by the bdftosnf conversion
* program and checked by the snffonts
* server routine.
*/
unsigned int terminalFont; /* Should be deprecated! true if:
constant metrics &&
leftSideBearing == 0 &&
rightSideBearing == characterWidth &&
ascent == fontAscent &&
descent == fontDescent
*/
unsigned int linear:1; /* true if firstRow == lastRow */
unsigned int constantWidth:1; /* true if minbounds->metrics.characterWidth
* == maxbounds->metrics.characterWidth
*/
unsigned int inkInside:1; /* true if for all defined glyphs:
* leftSideBearing >= 0 &&
* rightSideBearing <= characterWidth &&
* -fontDescent <= ascent <= fontAscent &&
* -fontAscent <= descent <= fontDescent
*/
unsigned int inkMetrics:1; /* ink metrics != bitmap metrics */
/* used with terminalFont */
/* see font's pInk{CI,Min,Max} */
unsigned int padding:28;
unsigned int firstCol;
unsigned int lastCol;
unsigned int firstRow;
unsigned int lastRow;
unsigned int nProps;
unsigned int lenStrings; /* length in bytes of string table */
unsigned int chDefault; /* default character */
int fontDescent; /* minimum for quality typography */
int fontAscent; /* minimum for quality typography */
CharInfoRec minbounds; /* MIN of glyph metrics over all chars */
CharInfoRec maxbounds; /* MAX of glyph metrics over all chars */
unsigned int pixDepth; /* intensity bits per pixel */
unsigned int glyphSets; /* number of sets of glyphs, for
sub-pixel positioning */
unsigned int version2; /* version stamp double-check */
} FontInfoRec;
typedef struct _FontInfo *FontInfoPtr;
typedef struct _Font {
FontInfoPtr pFI;
} FontRec;
typedef struct _Font *FontPtr;
FontRec ACTUALFONT;
FontInfoRec ACTUALPFI;
unsigned int A;
main ()
{
FontPtr pfont;
pfont = &ACTUALFONT;
pfont->pFI = &ACTUALPFI;
A = (pfont->pFI->maxbounds.byteOffset + 3) & ~3;
}
----------------------------------------------------------------------------
COMPILED WITH -fvolatile flag : cc68k -c -g -O -fvolatile gnubug.c -S
==================================================================
#NO_APP
gcc_compiled.:
.stabs "gnubug.c",100,0,0,Ltext
Ltext:
.stabs "int:t1=r1;-2147483648;2147483647;",128,0,0,0
.stabs "char:t2=r2;0;127;",128,0,0,0
.stabs "long int:t3=r1;-2147483648;2147483647;",128,0,0,0
.stabs "unsigned int:t4=r1;0;-1;",128,0,0,0
.stabs "long unsigned int:t5=r1;0;-1;",128,0,0,0
.stabs "short int:t6=r1;-32768;32767;",128,0,0,0
.stabs "long long int:t7=r1;0;-1;",128,0,0,0
.stabs "short unsigned int:t8=r1;0;65535;",128,0,0,0
.stabs "long long unsigned int:t9=r1;0;-1;",128,0,0,0
.stabs "signed char:t10=r1;-128;127;",128,0,0,0
.stabs "unsigned char:t11=r1;0;255;",128,0,0,0
.stabs "float:t12=r1;4;0;",128,0,0,0
.stabs "double:t13=r1;8;0;",128,0,0,0
.stabs "long double:t14=r1;8;0;",128,0,0,0
.stabs "void:t15=15",128,0,0,0
.stabs "_CharInfo:T16=s4byteOffset:1,0,24;exists:1,24,1;\\",128,0,0,0
.stabs "pad:1,25,7;;",128,0,0,0
.stabs "CharInfoRec:t16",128,0,0,0
.stabs "_FontInfo:T17=s88version1:4,0,32;allExist:4,32,32;\\",128,0,0,0
.stabs "drawDirection:4,64,32;noOverlap:4,96,32;constantMetrics:4,128,32;\\",128,0,0,0
.stabs "mcgFont:4,160,32;terminalFont:4,192,32;linear:1,224,1;\\",128,0,0,0
.stabs "constantWidth:1,225,1;inkInside:1,226,1;inkMetrics:1,227,1;\\",128,0,0,0
.stabs "padding:1,228,28;firstCol:4,256,32;lastCol:4,288,32;\\",128,0,0,0
.stabs "firstRow:4,320,32;lastRow:4,352,32;nProps:4,384,32;\\",128,0,0,0
.stabs "lenStrings:4,416,32;chDefault:4,448,32;fontDescent:1,480,32;\\",128,0,0,0
.stabs "fontAscent:1,512,32;minbounds:16,544,32;maxbounds:16,576,32;\\",128,0,0,0
.stabs "pixDepth:4,608,32;glyphSets:4,640,32;version2:4,672,32;;",128,0,0,0
.stabs "FontInfoRec:t17",128,0,0,0
.stabs "FontInfoPtr:t18=*17",128,0,0,0
.stabs "_Font:T19=s4pFI:18,0,32;;",128,0,0,0
.stabs "FontRec:t19",128,0,0,0
.stabs "FontPtr:t20=*19",128,0,0,0
.text
.even
.globl _main
_main:
.stabd 68,0,74
link a6,#0
LBB2:
.stabd 68,0,77
lea _ACTUALFONT,a0
.stabd 68,0,78
movel #_ACTUALPFI,a0@
.stabd 68,0,79
movel a0@,a0
moveb a0@(72),d0 ; This only moves the low order byte of the field
; It should move all 32 bits before extracting
; the upper 24 bits.
bfextu d0{#0:#24},d0
addql #3,d0
moveq #-4,d1
andl d1,d0
movel d0,_A
LBE2:
.stabd 68,0,80
unlk a6
rts
.stabs "main:F1",36,0,0,_main
.stabs "pfont:r20",64,0,0,8
.stabn 192,0,0,LBB2
.stabn 224,0,0,LBE2
.stabs "A:G4",32,0,0,0
.comm _A,4
.stabs "ACTUALPFI:G17",32,0,0,0
.comm _ACTUALPFI,88
.stabs "ACTUALFONT:G19",32,0,0,0
.comm _ACTUALFONT,4
------------------------------------------------------------------------
COMPILED WITHOUT -fvolatile: cc68k -c -g -O gnubug.c -S
====================================================
#NO_APP
gcc_compiled.:
.stabs "gnubug.c",100,0,0,Ltext
Ltext:
.stabs "int:t1=r1;-2147483648;2147483647;",128,0,0,0
.stabs "char:t2=r2;0;127;",128,0,0,0
.stabs "long int:t3=r1;-2147483648;2147483647;",128,0,0,0
.stabs "unsigned int:t4=r1;0;-1;",128,0,0,0
.stabs "long unsigned int:t5=r1;0;-1;",128,0,0,0
.stabs "short int:t6=r1;-32768;32767;",128,0,0,0
.stabs "long long int:t7=r1;0;-1;",128,0,0,0
.stabs "short unsigned int:t8=r1;0;65535;",128,0,0,0
.stabs "long long unsigned int:t9=r1;0;-1;",128,0,0,0
.stabs "signed char:t10=r1;-128;127;",128,0,0,0
.stabs "unsigned char:t11=r1;0;255;",128,0,0,0
.stabs "float:t12=r1;4;0;",128,0,0,0
.stabs "double:t13=r1;8;0;",128,0,0,0
.stabs "long double:t14=r1;8;0;",128,0,0,0
.stabs "void:t15=15",128,0,0,0
.stabs "_CharInfo:T16=s4byteOffset:1,0,24;exists:1,24,1;\\",128,0,0,0
.stabs "pad:1,25,7;;",128,0,0,0
.stabs "CharInfoRec:t16",128,0,0,0
.stabs "_FontInfo:T17=s88version1:4,0,32;allExist:4,32,32;\\",128,0,0,0
.stabs "drawDirection:4,64,32;noOverlap:4,96,32;constantMetrics:4,128,32;\\",128,0,0,0
.stabs "mcgFont:4,160,32;terminalFont:4,192,32;linear:1,224,1;\\",128,0,0,0
.stabs "constantWidth:1,225,1;inkInside:1,226,1;inkMetrics:1,227,1;\\",128,0,0,0
.stabs "padding:1,228,28;firstCol:4,256,32;lastCol:4,288,32;\\",128,0,0,0
.stabs "firstRow:4,320,32;lastRow:4,352,32;nProps:4,384,32;\\",128,0,0,0
.stabs "lenStrings:4,416,32;chDefault:4,448,32;fontDescent:1,480,32;\\",128,0,0,0
.stabs "fontAscent:1,512,32;minbounds:16,544,32;maxbounds:16,576,32;\\",128,0,0,0
.stabs "pixDepth:4,608,32;glyphSets:4,640,32;version2:4,672,32;;",128,0,0,0
.stabs "FontInfoRec:t17",128,0,0,0
.stabs "FontInfoPtr:t18=*17",128,0,0,0
.stabs "_Font:T19=s4pFI:18,0,32;;",128,0,0,0
.stabs "FontRec:t19",128,0,0,0
.stabs "FontPtr:t20=*19",128,0,0,0
.text
.even
.globl _main
_main:
.stabd 68,0,74
link a6,#0
LBB2:
.stabd 68,0,77
.stabd 68,0,78
movel #_ACTUALPFI,_ACTUALFONT
.stabd 68,0,79
bfextu _ACTUALPFI+72{#0:#24},d0
addql #3,d0
moveq #-4,d1
andl d1,d0
movel d0,_A
LBE2:
.stabd 68,0,80
unlk a6
rts
.stabs "main:F1",36,0,0,_main
.stabn 192,0,0,LBB2
.stabn 224,0,0,LBE2
.stabs "A:G4",32,0,0,0
.comm _A,4
.stabs "ACTUALPFI:G17",32,0,0,0
.comm _ACTUALPFI,88
.stabs "ACTUALFONT:G19",32,0,0,0
.comm _ACTUALFONT,4
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