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Fixed and improved the code for compares. Before, compares of chars to a
constant where sometimes passed down to the code generator in a way that caused wrong code to be generated. This change may go into 2.13 after some testing. git-svn-id: svn://svn.cc65.org/cc65/trunk@4743 b7a2c559-68d2-44c3-8de9-860c34a00d81
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uz
parent
4cd7eec075
commit
2bb2d97ab0
182
src/cc65/expr.c
182
src/cc65/expr.c
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@ -109,12 +109,13 @@ void ExprWithCheck (void (*Func) (ExprDesc*), ExprDesc* Expr)
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/* Do some checks if code generation is still constistent */
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if (StackPtr != OldSP) {
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if (Debug) {
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fprintf (stderr,
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"Code generation messed up!\n"
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"StackPtr is %d, should be %d",
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StackPtr, OldSP);
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Error ("Code generation messed up: "
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"StackPtr is %d, should be %d",
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StackPtr, OldSP);
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} else {
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Internal ("StackPtr is %d, should be %d\n", StackPtr, OldSP);
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Internal ("Code generation messed up: "
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"StackPtr is %d, should be %d",
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StackPtr, OldSP);
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}
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}
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}
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@ -255,6 +256,18 @@ void PushAddr (const ExprDesc* Expr)
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static void WarnConstCompareResult (void)
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/* If the result of a comparison is constant, this is suspicious when not in
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* preprocessor mode.
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*/
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{
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if (!Preprocessing) {
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Warning ("Result of comparison is constant");
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}
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}
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/*****************************************************************************/
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/* code */
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/*****************************************************************************/
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@ -1904,18 +1917,23 @@ static void hie_compare (const GenDesc* Ops, /* List of generators */
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/* Helper function for the compare operators */
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{
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ExprDesc Expr2;
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CodeMark Mark0;
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CodeMark Mark1;
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CodeMark Mark2;
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const GenDesc* Gen;
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token_t Tok; /* The operator token */
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token_t Tok; /* The operator token */
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unsigned ltype;
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int rconst; /* Operand is a constant */
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GetCodePos (&Mark0);
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hienext (Expr);
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while ((Gen = FindGen (CurTok.Tok, Ops)) != 0) {
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/* Remember the generator function */
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void (*GenFunc) (unsigned, unsigned long) = Gen->Func;
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/* Remember the operator token, then skip it */
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Tok = CurTok.Tok;
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NextToken ();
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@ -1971,9 +1989,7 @@ static void hie_compare (const GenDesc* Ops, /* List of generators */
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/* If the result is constant, this is suspicious when not in
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* preprocessor mode.
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*/
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if (!Preprocessing) {
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Warning ("Result of comparison is constant");
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}
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WarnConstCompareResult ();
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/* Both operands are constant, remove the generated code */
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RemoveCode (&Mark1);
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@ -2011,7 +2027,7 @@ static void hie_compare (const GenDesc* Ops, /* List of generators */
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}
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}
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} else {
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} else {
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/* If the right hand side is constant, and the generator function
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* expects the lhs in the primary, remove the push of the primary
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@ -2026,27 +2042,139 @@ static void hie_compare (const GenDesc* Ops, /* List of generators */
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}
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}
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/* Determine the type of the operation result. If the left
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* operand is of type char and the right is a constant, or
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* if both operands are of type char, we will encode the
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* operation as char operation. Otherwise the default
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* promotions are used.
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*/
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if (IsTypeChar (Expr->Type) && (IsTypeChar (Expr2.Type) || rconst)) {
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flags |= CF_CHAR;
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if (IsSignUnsigned (Expr->Type) || IsSignUnsigned (Expr2.Type)) {
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flags |= CF_UNSIGNED;
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}
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if (rconst) {
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flags |= CF_FORCECHAR;
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}
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/* Determine the type of the operation. */
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if (IsTypeChar (Expr->Type) && rconst) {
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/* Left side is unsigned char, right side is constant */
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int LeftSigned = IsSignSigned (Expr->Type);
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int RightSigned = IsSignSigned (Expr2.Type);
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/* Determine the minimum and maximum values */
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int LeftMin, LeftMax;
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if (LeftSigned) {
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LeftMin = -128;
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LeftMax = 127;
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} else {
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LeftMin = 0;
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LeftMax = 255;
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}
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/* An integer value is always represented as a signed in the
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* ExprDesc structure. This may lead to false results below,
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* if it is actually unsigned, but interpreted as signed
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* because of the representation. Fortunately, in this case,
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* the actual value doesn't matter, since it's always greater
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* than what can be represented in a char. So correct the
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* value accordingly.
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*/
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if (!RightSigned && Expr2.IVal < 0) {
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/* Correct the value so it is an unsigned. It will then
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* anyway match one of the cases below.
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*/
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Expr2.IVal = LeftMax + 1;
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}
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/* Comparing a char against a constant may have a constant
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* result.
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*/
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switch (Tok) {
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case TOK_EQ:
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if (Expr2.IVal < LeftMin || Expr2.IVal > LeftMax) {
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ED_MakeConstAbsInt (Expr, 0);
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WarnConstCompareResult ();
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RemoveCode (&Mark0);
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goto Done;
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}
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break;
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case TOK_NE:
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if (Expr2.IVal < LeftMin || Expr2.IVal > LeftMax) {
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ED_MakeConstAbsInt (Expr, 1);
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WarnConstCompareResult ();
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RemoveCode (&Mark0);
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goto Done;
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}
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break;
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case TOK_LT:
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if (Expr2.IVal <= LeftMin || Expr2.IVal > LeftMax) {
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ED_MakeConstAbsInt (Expr, Expr2.IVal > LeftMax);
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WarnConstCompareResult ();
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RemoveCode (&Mark0);
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goto Done;
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}
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break;
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case TOK_LE:
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if (Expr2.IVal < LeftMin || Expr2.IVal >= LeftMax) {
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ED_MakeConstAbsInt (Expr, Expr2.IVal >= LeftMax);
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WarnConstCompareResult ();
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RemoveCode (&Mark0);
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goto Done;
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} else if (!LeftSigned && Expr2.IVal == 0) {
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/* We can replace this by a compare to zero, because
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* the value of lhs may never be negative.
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*/
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GenFunc = g_eq;
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}
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break;
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case TOK_GE:
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if (Expr2.IVal <= LeftMin || Expr2.IVal > LeftMax) {
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ED_MakeConstAbsInt (Expr, Expr2.IVal <= LeftMin);
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WarnConstCompareResult ();
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RemoveCode (&Mark0);
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goto Done;
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}
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break;
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case TOK_GT:
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if (Expr2.IVal < LeftMin || Expr2.IVal >= LeftMax) {
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ED_MakeConstAbsInt (Expr, Expr2.IVal < LeftMin);
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WarnConstCompareResult ();
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RemoveCode (&Mark0);
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goto Done;
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} else if (!LeftSigned && Expr2.IVal == 0) {
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/* We can replace this by a compare to zero, because
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* the value of lhs may never be negative.
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*/
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GenFunc = g_ne;
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}
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break;
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default:
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Internal ("hie_compare: got token 0x%X\n", Tok);
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}
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/* If the result is not already constant (as evaluated in the
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* switch above), we can execute the operation as a char op,
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* since the right side constant is in a valid range.
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*/
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flags |= (CF_CHAR | CF_FORCECHAR);
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if (!LeftSigned) {
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flags |= CF_UNSIGNED;
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}
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} else if (IsTypeChar (Expr->Type) && IsTypeChar (Expr2.Type) &&
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GetSignedness (Expr->Type) == GetSignedness (Expr2.Type)) {
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/* Both are chars with the same signedness. We can encode the
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* operation as a char operation.
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*/
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flags |= CF_CHAR;
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if (rconst) {
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flags |= CF_FORCECHAR;
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}
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if (IsSignUnsigned (Expr->Type)) {
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flags |= CF_UNSIGNED;
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}
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} else {
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unsigned rtype = TypeOf (Expr2.Type) | (flags & CF_CONST);
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unsigned rtype = TypeOf (Expr2.Type) | (flags & CF_CONST);
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flags |= g_typeadjust (ltype, rtype);
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}
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/* Generate code */
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Gen->Func (flags, Expr2.IVal);
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GenFunc (flags, Expr2.IVal);
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/* The result is an rvalue in the primary */
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ED_MakeRValExpr (Expr);
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@ -2055,7 +2183,7 @@ static void hie_compare (const GenDesc* Ops, /* List of generators */
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/* Result type is always int */
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Expr->Type = type_int;
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/* Condition codes are set */
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Done: /* Condition codes are set */
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ED_TestDone (Expr);
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}
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}
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