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Improved the code generated for bit-fields.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@4096 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz
2009-08-31 14:59:49 +00:00
parent 0a9c7484ad
commit dc678e8dcb
5 changed files with 146 additions and 9 deletions
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46
src/cc65/assignment.c
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@@ -34,6 +34,7 @@
/* cc65 */
#include "asmcode.h"
#include "assignment.h"
#include "codegen.h"
#include "datatype.h"
@@ -160,6 +161,9 @@ void Assignment (ExprDesc* Expr)
} else if (ED_IsBitField (Expr)) {
CodeMark AndPos;
CodeMark PushPos;
unsigned Mask;
unsigned Flags;
@@ -182,30 +186,54 @@ void Assignment (ExprDesc* Expr)
/* Mask unwanted bits */
Mask = (0x0001U << Expr->BitWidth) - 1U;
GetCodePos (&AndPos);
g_and (Flags | CF_CONST, ~(Mask << Expr->BitOffs));
/* Push it on stack */
GetCodePos (&PushPos);
g_push (Flags, 0);
/* Read the expression on the right side of the '=' */
hie1 (&Expr2);
/* Do type conversion if necessary. Beware: Do not use char type
/* Do type conversion if necessary. Beware: Do not use char type
* here!
*/
TypeConversion (&Expr2, ltype);
/* If necessary, load the value into the primary register */
LoadExpr (CF_NONE, &Expr2);
/* Special treatment if the value is constant */
if (ED_IsConstAbsInt (&Expr2)) {
/* Apply the mask */
g_and (Flags | CF_CONST, Mask);
/* Get the value and apply the mask */
unsigned Val = (unsigned) (Expr2.IVal & Mask);
/* Shift it into the right position */
g_asl (Flags | CF_CONST, Expr->BitOffs);
/* Since we will do the OR with a constant, we can remove the push */
RemoveCode (&PushPos);
/* Or both values */
g_or (Flags, 0);
/* If the value is equal to the mask now, all bits are one, and we
* can remove the mask operation from above.
*/
if (Val == Mask) {
RemoveCode (&AndPos);
}
/* Generate the or operation */
g_or (Flags | CF_CONST, Val << Expr->BitOffs);
} else {
/* If necessary, load the value into the primary register */
LoadExpr (CF_NONE, &Expr2);
/* Apply the mask */
g_and (Flags | CF_CONST, Mask);
/* Shift it into the right position */
g_asl (Flags | CF_CONST, Expr->BitOffs);
/* Or both values */
g_or (Flags, 0);
}
/* Generate a store instruction */
Store (Expr, 0);