Commit 76e050c2e62995f1d6905e28674dea3a7fcff1a5
1 parent
da2414e9
Fix overflow conditions for MIPS add / subtract (Stefan Weil)
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@1828 c046a42c-6fe2-441c-8c8c-71466251a162
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4 additions
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2 deletions
target-mips/op.c
| @@ -206,7 +206,8 @@ void op_addo (void) | @@ -206,7 +206,8 @@ void op_addo (void) | ||
| 206 | 206 | ||
| 207 | tmp = T0; | 207 | tmp = T0; |
| 208 | T0 += T1; | 208 | T0 += T1; |
| 209 | - if ((T0 >> 31) ^ (T1 >> 31) ^ (tmp >> 31)) { | 209 | + if (((tmp ^ T1 ^ (-1)) & (T0 ^ T1)) >> 31) { |
| 210 | + /* operands of same sign, result different sign */ | ||
| 210 | CALL_FROM_TB1(do_raise_exception_direct, EXCP_OVERFLOW); | 211 | CALL_FROM_TB1(do_raise_exception_direct, EXCP_OVERFLOW); |
| 211 | } | 212 | } |
| 212 | RETURN(); | 213 | RETURN(); |
| @@ -224,7 +225,8 @@ void op_subo (void) | @@ -224,7 +225,8 @@ void op_subo (void) | ||
| 224 | 225 | ||
| 225 | tmp = T0; | 226 | tmp = T0; |
| 226 | T0 = (int32_t)T0 - (int32_t)T1; | 227 | T0 = (int32_t)T0 - (int32_t)T1; |
| 227 | - if (!((T0 >> 31) ^ (T1 >> 31) ^ (tmp >> 31))) { | 228 | + if (((tmp ^ T1) & (tmp ^ T0)) >> 31) { |
| 229 | + /* operands of different sign, first operand and result different sign */ | ||
| 228 | CALL_FROM_TB1(do_raise_exception_direct, EXCP_OVERFLOW); | 230 | CALL_FROM_TB1(do_raise_exception_direct, EXCP_OVERFLOW); |
| 229 | } | 231 | } |
| 230 | RETURN(); | 232 | RETURN(); |