gbdev/rgbds
1
0
Fork 0
mirror of https://github.com/gbdev/rgbds.git synced 2026-08-21 06:14:35 +00:00
Code Issues Packages Projects Releases Wiki Activity

Fix $8000_0000 % -1 to warn with -Wdiv like $8000_0000 / -1 does (#2012)

Browse Source
This commit is contained in:
Rangi
2026-07-06 15:08:44 -04:00
committed by GitHub
parent be3fc61859
commit 46a6966b70
6 changed files with 25 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/asm/rpn.cpp
+3 -4
View File
@@ -375,8 +375,7 @@ void Expression::makeBinaryOp(RPNCommand op, Expression &&src1, Expression const
case RPN_DIV:
if (rval == 0) {
fatal("Division by zero");
}
if (lval == INT32_MIN && rval == -1) {
} else if (lval == INT32_MIN && rval == -1) {
warning(
WARNING_DIV,
"Division of %" PRId32 " by -1 yields %" PRId32,
@@ -391,8 +390,8 @@ void Expression::makeBinaryOp(RPNCommand op, Expression &&src1, Expression const
case RPN_MOD:
if (rval == 0) {
fatal("Modulo by zero");
}
if (lval == INT32_MIN && rval == -1) {
} else if (lval == INT32_MIN && rval == -1) {
warning(WARNING_DIV, "Modulo of %" PRId32 " by -1 yields 0", INT32_MIN);
data = 0;
} else {
data = op_modulo(lval, rval);
src/link/patch.cpp
+4 -1
View File
@@ -143,8 +143,11 @@ static int32_t computeRPNExpr(Patch const &patch, std::vector<Symbol> const &fil
firstErrorAt(patch, "Modulo by 0");
popRPN(patch);
value = 0;
} else if (int32_t lval = popRPN(patch); lval == INT32_MIN && value == -1) {
diagnosticAt(patch, WARNING_DIV, "Modulo of %" PRId32 " by -1 yields 0", INT32_MIN);
value = 0;
} else {
value = op_modulo(popRPN(patch), value);
value = op_modulo(lval, value);
}
break;
case RPN_NEG:
src/opmath.cpp
+5 -1
View File
@@ -6,9 +6,11 @@
#include <stdint.h>
#include "helpers.hpp" // clz, ctz
#include "helpers.hpp" // assume, clz, ctz
int32_t op_divide(int32_t dividend, int32_t divisor) {
assume(divisor != 0); // Division by 0 is UB
assume(dividend != INT32_MIN || divisor != -1); // INT32_MIN / -1 is UB
// Adjust division to floor toward negative infinity,
// not truncate toward zero
int32_t remainder = dividend % divisor;
@@ -16,6 +18,8 @@ int32_t op_divide(int32_t dividend, int32_t divisor) {
}
int32_t op_modulo(int32_t dividend, int32_t divisor) {
assume(divisor != 0); // Modulo by 0 is UB
assume(dividend != INT32_MIN || divisor != -1); // INT32_MIN % -1 is UB
// Adjust modulo to have the sign of the divisor,
// not the sign of the dividend
return static_cast<int32_t>(
test/asm/overflow.err
+4
View File
@@ -2,6 +2,10 @@ warning: Division of -2147483648 by -1 yields -2147483648 [-Wdiv]
at overflow.asm(23)
warning: Division of -2147483648 by -1 yields -2147483648 [-Wdiv]
at overflow.asm(24)
warning: Modulo of -2147483648 by -1 yields 0 [-Wdiv]
at overflow.asm(28)
warning: Modulo of -2147483648 by -1 yields 0 [-Wdiv]
at overflow.asm(29)
warning: Integer constant is too large [-Wlarge-constant]
at overflow.asm(44)
warning: Graphics constant has too many digits; only first 8 pixels considered [-Wlarge-constant]
test/link/patch-diagnostics.asm
+1
View File
@@ -2,6 +2,7 @@ def fzero equs "startof(\"test\")"
section "test", rom0
ld a, $8000_0000 / ({fzero} - 1)
ld a, $8000_0000 / ({fzero} - 2)
ld a, $8000_0000 % ({fzero} - 1)
ld a, 1 << ({fzero} - 1)
ld a, 1 << ({fzero} + 32)
ld a, ({fzero} - 1) >> 1
test/link/patch-diagnostics.out
+8 -6
View File
@@ -1,16 +1,18 @@
warning: Shifting right by large amount 32 [-Wshift-amount]
at patch-diagnostics.asm(12)
warning: Shifting right by negative amount -1 [-Wshift-amount]
at patch-diagnostics.asm(11)
warning: Shifting right by negative amount -1 [-Wshift-amount]
at patch-diagnostics.asm(10)
warning: Shifting right by large amount 32 [-Wshift-amount]
at patch-diagnostics.asm(9)
at patch-diagnostics.asm(10)
warning: Shifting right by negative amount -1 [-Wshift-amount]
at patch-diagnostics.asm(8)
at patch-diagnostics.asm(9)
warning: Shifting right negative value -1 [-Wshift]
at patch-diagnostics.asm(7)
at patch-diagnostics.asm(8)
warning: Shifting left by large amount 32 [-Wshift-amount]
at patch-diagnostics.asm(6)
at patch-diagnostics.asm(7)
warning: Shifting left by negative amount -1 [-Wshift-amount]
at patch-diagnostics.asm(6)
warning: Modulo of -2147483648 by -1 yields 0 [-Wdiv]
at patch-diagnostics.asm(5)
warning: Value $40000000 is not 8-bit [-Wtruncation]
at patch-diagnostics.asm(4)