| Message ID | 20200806193003.10144-5-luc.vanoostenryck@gmail.com (mailing list archive) |
|---|---|
| State | Mainlined, archived |
| Headers | show |
| Series | Fix shifts-assigns and avoid warns on deadcode | expand |
On Thu, Aug 06, 2020 at 09:30:03PM +0200, Luc Van Oostenryck wrote: > Sparse complains when a shift amount is too big for the size > of its operand or if it's negative. > > However, it does this even for expressions that are never evaluated. > It's especially annoying in the kernel for type generic macros, > for example the ones in arch/*/include/asm/cmpxchg.h > > So, remove all warnings done at expansion time and avoid any > simplifications of such expressions. Same, at linearization > and optimization time but in this case mark the instructions as > 'tainted' to inhibit any further simplifications. Finally, at the > end of the optimization phase, warn for the tainted instructions. > > Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> > --- > expand.c | 18 ------------- > linearize.c | 44 ++++++++++++++++++++++++++++++++ > simplify.c | 20 ++++----------- > validation/expand/bad-shift.c | 8 +++--- > validation/optim/shift-big.c | 12 ++++++--- > validation/shift-negative.c | 4 +-- > validation/shift-undef-long.c | 7 +++-- > validation/shift-undef.c | 48 +++++++++-------------------------- > 8 files changed, 78 insertions(+), 83 deletions(-) > > diff --git a/expand.c b/expand.c > index b07893318382..623b180025ad 100644 > --- a/expand.c > +++ b/expand.c > @@ -170,22 +170,6 @@ Float: > expr->type = EXPR_FVALUE; > } > > -static void warn_shift_count(struct expression *expr, struct symbol *ctype, long long count) > -{ > - if (count < 0) { > - if (!Wshift_count_negative) > - return; > - warning(expr->pos, "shift count is negative (%lld)", count); > - return; > - } > - if (ctype->type == SYM_NODE) > - ctype = ctype->ctype.base_type; > - > - if (!Wshift_count_overflow) > - return; > - warning(expr->pos, "shift too big (%llu) for type %s", count, show_typename(ctype)); > -} > - > /* Return true if constant shift size is valid */ > static bool check_shift_count(struct expression *expr, struct expression *right) > { > @@ -194,8 +178,6 @@ static bool check_shift_count(struct expression *expr, struct expression *right) > > if (count >= 0 && count < ctype->bit_size) > return true; > - if (!conservative) > - warn_shift_count(expr, ctype, count); > return false; > } > > diff --git a/linearize.c b/linearize.c > index 4927468183b0..5a8e74970d98 100644 > --- a/linearize.c > +++ b/linearize.c > @@ -2468,6 +2468,49 @@ static pseudo_t linearize_statement(struct entrypoint *ep, struct statement *stm > return VOID; > } > > +static void check_tainted_insn(struct instruction *insn) > +{ > + unsigned long long uval; > + long long sval; > + pseudo_t src2; > + > + switch (insn->opcode) { > + case OP_DIVU: case OP_DIVS: > + case OP_MODU: case OP_MODS: > + if (insn->src2 == value_pseudo(0)) > + warning(insn->pos, "divide by zero"); > + break; Is this divide by zero a new check? I get the shift, but is this new? > + case OP_SHL: case OP_LSR: case OP_ASR: > + src2 = insn->src2; > + if (src2->type != PSEUDO_VAL) > + break; > + uval = src2->value; > + if (uval < insn->size) > + break; > + sval = sign_extend(uval, insn->size); > + if (Wshift_count_negative && sval < 0) > + warning(insn->pos, "shift count is negative (%lld)", sval); > + else if (Wshift_count_overflow) > + warning(insn->pos, "shift too big (%llu) for type %s", uval, show_typename(insn->type)); Makes sense. > + } > +} > + > +/// > +// issue warnings after all possible DCE > +static void late_warnings(struct entrypoint *ep) > +{ > + struct basic_block *bb; > + FOR_EACH_PTR(ep->bbs, bb) { > + struct instruction *insn; > + FOR_EACH_PTR(bb->insns, insn) { > + if (!insn->bb) > + continue; > + if (insn->tainted) > + check_tainted_insn(insn); > + } END_FOR_EACH_PTR(insn); > + } END_FOR_EACH_PTR(bb); > +} > + > static struct entrypoint *linearize_fn(struct symbol *sym, struct symbol *base_type) > { > struct statement *stmt = base_type->stmt; > @@ -2514,6 +2557,7 @@ static struct entrypoint *linearize_fn(struct symbol *sym, struct symbol *base_t > add_one_insn(ep, ret); > > optimize(ep); > + late_warnings(ep); > return ep; > } > > diff --git a/simplify.c b/simplify.c > index 7850bcdc6069..f6b79685f439 100644 > --- a/simplify.c > +++ b/simplify.c > @@ -754,28 +754,18 @@ static long long check_shift_count(struct instruction *insn, unsigned long long > unsigned int size = insn->size; > long long sval = uval; > > + if (insn->tainted) > + return -1; > + > if (uval < size) > return uval; > > + insn->tainted = 1; > sval = sign_extend_safe(sval, size); > sval = sign_extend_safe(sval, bits_in_int); > if (sval < 0) > insn->src2 = value_pseudo(sval); > - if (insn->tainted) > - return sval; > - > - if (sval < 0 && Wshift_count_negative) > - warning(insn->pos, "shift count is negative (%lld)", sval); > - if (sval > 0 && Wshift_count_overflow) { > - struct symbol *ctype = insn->type; > - const char *tname; > - if (ctype->type == SYM_NODE) > - ctype = ctype->ctype.base_type; > - tname = show_typename(ctype); > - warning(insn->pos, "shift too big (%llu) for type %s", sval, tname); > - } > - insn->tainted = 1; > - return sval; > + return -1; > } > > static int simplify_shift(struct instruction *insn, pseudo_t pseudo, long long value) > diff --git a/validation/expand/bad-shift.c b/validation/expand/bad-shift.c > index 22c4341f1680..b68866c2b048 100644 > --- a/validation/expand/bad-shift.c > +++ b/validation/expand/bad-shift.c > @@ -56,9 +56,9 @@ rneg: > * check-output-end > * > * check-error-start > -expand/bad-shift.c:5:18: warning: shift too big (32) for type int > -expand/bad-shift.c:10:18: warning: shift count is negative (-1) > -expand/bad-shift.c:15:18: warning: shift too big (32) for type int > -expand/bad-shift.c:20:18: warning: shift count is negative (-1) > +expand/bad-shift.c:5:21: warning: shift too big (32) for type int > +expand/bad-shift.c:10:21: warning: shift count is negative (-1) > +expand/bad-shift.c:15:21: warning: shift too big (32) for type int > +expand/bad-shift.c:20:21: warning: shift count is negative (-1) > * check-error-end > */ > diff --git a/validation/optim/shift-big.c b/validation/optim/shift-big.c > index 84bcd2ce01a3..e7bf22fe36ff 100644 > --- a/validation/optim/shift-big.c > +++ b/validation/optim/shift-big.c > @@ -50,13 +50,15 @@ lsr31: > lsr32: > .L8: > <entry-point> > - ret.32 $0 > + lsr.32 %r14 <- %arg1, $32 > + ret.32 %r14 > > > lsr33: > .L10: > <entry-point> > - ret.32 $0 > + lsr.32 %r17 <- %arg1, $33 > + ret.32 %r17 > > > shl31: > @@ -69,13 +71,15 @@ shl31: > shl32: > .L14: > <entry-point> > - ret.32 $0 > + shl.32 %r23 <- %arg1, $32 > + ret.32 %r23 > > > shl33: > .L16: > <entry-point> > - ret.32 $0 > + shl.32 %r26 <- %arg1, $33 > + ret.32 %r26 > > > * check-output-end > diff --git a/validation/shift-negative.c b/validation/shift-negative.c > index fff5cf123dd6..6df02b18468f 100644 > --- a/validation/shift-negative.c > +++ b/validation/shift-negative.c > @@ -9,8 +9,8 @@ unsigned int fo2(unsigned int a) { return a >> ((a & 0) ^ ~0); } > * check-command: sparse -Wno-decl $file > * > * check-error-start > -shift-negative.c:1:45: warning: shift count is negative (-1) > -shift-negative.c:2:45: warning: shift count is negative (-1) > +shift-negative.c:1:48: warning: shift count is negative (-1) > +shift-negative.c:2:48: warning: shift count is negative (-1) > shift-negative.c:4:59: warning: shift count is negative (-1) > shift-negative.c:5:59: warning: shift count is negative (-1) > * check-error-end > diff --git a/validation/shift-undef-long.c b/validation/shift-undef-long.c > index 326267436ec7..985fe4c4c595 100644 > --- a/validation/shift-undef-long.c > +++ b/validation/shift-undef-long.c > @@ -13,9 +13,8 @@ static unsigned very_big_shift(unsigned int a) > * check-command: sparse -m64 $file > * > * check-error-start > -shift-undef-long.c:4:16: warning: shift too big (4294967295) for type unsigned int > -shift-undef-long.c:5:16: warning: shift too big (4294967296) for type unsigned int > -shift-undef-long.c:6:16: warning: shift too big (4294967296) for type unsigned int > -shift-undef-long.c:7:16: warning: shift count is negative (-4294967296) > +shift-undef-long.c:4:25: warning: shift count is negative (-1) > +shift-undef-long.c:5:47: warning: shift too big (4294967296) for type unsigned int > +shift-undef-long.c:7:20: warning: shift count is negative (-4294967296) > * check-error-end > */ > diff --git a/validation/shift-undef.c b/validation/shift-undef.c > index 613c6b95b113..0c7541e9ffd9 100644 > --- a/validation/shift-undef.c > +++ b/validation/shift-undef.c > @@ -112,48 +112,24 @@ void hw_write(u32 val) > * check-command: sparse -Wno-decl $file > * > * check-error-start > -shift-undef.c:3:15: warning: shift too big (100) for type int > -shift-undef.c:4:15: warning: shift too big (101) for type unsigned int > -shift-undef.c:5:15: warning: shift too big (102) for type unsigned int > -shift-undef.c:6:15: warning: shift count is negative (-1) > -shift-undef.c:7:15: warning: shift count is negative (-2) > -shift-undef.c:8:15: warning: shift count is negative (-3) > -shift-undef.c:9:25: warning: shift too big (103) for type int > -shift-undef.c:10:25: warning: shift too big (104) for type unsigned int > -shift-undef.c:11:25: warning: shift too big (105) for type unsigned int > -shift-undef.c:12:25: warning: shift count is negative (-4) > -shift-undef.c:13:25: warning: shift count is negative (-5) > -shift-undef.c:14:25: warning: shift count is negative (-6) > -shift-undef.c:15:30: warning: shift too big (106) for type int > -shift-undef.c:16:30: warning: shift too big (107) for type unsigned int > -shift-undef.c:17:30: warning: shift too big (108) for type unsigned int > -shift-undef.c:18:30: warning: shift count is negative (-7) > -shift-undef.c:19:30: warning: shift count is negative (-8) > -shift-undef.c:20:30: warning: shift count is negative (-9) > +shift-undef.c:3:18: warning: shift too big (100) for type int > +shift-undef.c:4:18: warning: shift too big (101) for type unsigned int > +shift-undef.c:5:18: warning: shift too big (102) for type unsigned int > +shift-undef.c:6:19: warning: shift count is negative (-1) > +shift-undef.c:7:19: warning: shift count is negative (-2) > +shift-undef.c:8:19: warning: shift count is negative (-3) > shift-undef.c:21:29: warning: shift too big (109) for type int > shift-undef.c:22:29: warning: shift too big (110) for type unsigned int > shift-undef.c:23:29: warning: shift too big (111) for type unsigned int > shift-undef.c:24:29: warning: shift count is negative (-10) > shift-undef.c:25:29: warning: shift count is negative (-11) > shift-undef.c:26:29: warning: shift count is negative (-12) > -shift-undef.c:32:11: warning: shift too big (100) for type int > -shift-undef.c:33:11: warning: shift too big (101) for type unsigned int > -shift-undef.c:34:11: warning: shift too big (102) for type unsigned int > -shift-undef.c:35:11: warning: shift count is negative (-1) > -shift-undef.c:36:11: warning: shift too big (4294967294) for type unsigned int > -shift-undef.c:37:11: warning: shift too big (4294967293) for type unsigned int > -shift-undef.c:38:25: warning: shift too big (103) for type int > -shift-undef.c:39:25: warning: shift too big (104) for type unsigned int > -shift-undef.c:40:25: warning: shift too big (105) for type unsigned int > -shift-undef.c:41:25: warning: shift count is negative (-4) > -shift-undef.c:42:25: warning: shift too big (4294967291) for type unsigned int > -shift-undef.c:43:25: warning: shift too big (4294967290) for type unsigned int > -shift-undef.c:44:30: warning: shift too big (106) for type int > -shift-undef.c:45:30: warning: shift too big (107) for type unsigned int > -shift-undef.c:46:30: warning: shift too big (108) for type unsigned int > -shift-undef.c:47:30: warning: shift count is negative (-7) > -shift-undef.c:48:30: warning: shift too big (4294967288) for type unsigned int > -shift-undef.c:49:30: warning: shift too big (4294967287) for type unsigned int > +shift-undef.c:32:15: warning: shift too big (100) for type int > +shift-undef.c:33:15: warning: shift too big (101) for type unsigned int > +shift-undef.c:34:15: warning: shift too big (102) for type unsigned int > +shift-undef.c:35:16: warning: shift count is negative (-1) > +shift-undef.c:36:16: warning: shift count is negative (-2) > +shift-undef.c:37:16: warning: shift count is negative (-3) > shift-undef.c:50:26: warning: shift too big (109) for type int > shift-undef.c:51:26: warning: shift too big (110) for type unsigned int > shift-undef.c:52:26: warning: shift too big (111) for type unsigned int > -- > 2.28.0 >
On Sat, Aug 15, 2020 at 06:57:03PM +0900, Stafford Horne wrote: > On Thu, Aug 06, 2020 at 09:30:03PM +0200, Luc Van Oostenryck wrote: > > --- a/linearize.c > > +++ b/linearize.c > > @@ -2468,6 +2468,49 @@ static pseudo_t linearize_statement(struct entrypoint *ep, struct statement *stm > > return VOID; > > } > > > > +static void check_tainted_insn(struct instruction *insn) > > +{ > > + unsigned long long uval; > > + long long sval; > > + pseudo_t src2; > > + > > + switch (insn->opcode) { > > + case OP_DIVU: case OP_DIVS: > > + case OP_MODU: case OP_MODS: > > + if (insn->src2 == value_pseudo(0)) > > + warning(insn->pos, "divide by zero"); > > + break; > > Is this divide by zero a new check? I get the shift, but is this new? Yes, and no. The warning is already given (using 'division by zero') but, like for shifts before this series, issued early, before dead code elimination is done. So, code like the following: ... if (d != 0) r = a / d; ... issues the warning nevertheless. So, the check here above is now unused but is a preparation for the part 2 doing the same for division by zero by zero. Best regards, -- Luc
On Sat, Aug 15, 2020 at 01:15:40PM +0200, Luc Van Oostenryck wrote: > On Sat, Aug 15, 2020 at 06:57:03PM +0900, Stafford Horne wrote: > > On Thu, Aug 06, 2020 at 09:30:03PM +0200, Luc Van Oostenryck wrote: > > > --- a/linearize.c > > > +++ b/linearize.c > > > @@ -2468,6 +2468,49 @@ static pseudo_t linearize_statement(struct entrypoint *ep, struct statement *stm > > > return VOID; > > > } > > > > > > +static void check_tainted_insn(struct instruction *insn) > > > +{ > > > + unsigned long long uval; > > > + long long sval; > > > + pseudo_t src2; > > > + > > > + switch (insn->opcode) { > > > + case OP_DIVU: case OP_DIVS: > > > + case OP_MODU: case OP_MODS: > > > + if (insn->src2 == value_pseudo(0)) > > > + warning(insn->pos, "divide by zero"); > > > + break; > > > > Is this divide by zero a new check? I get the shift, but is this new? > > Yes, and no. The warning is already given (using 'division by zero') > but, like for shifts before this series, issued early, before dead code > elimination is done. So, code like the following: > ... > if (d != 0) > r = a / d; > ... > issues the warning nevertheless. So, the check here above is now unused > but is a preparation for the part 2 doing the same for division by zero > by zero. I see, it's preparation for part 2, makes sense. -Stafford
diff --git a/expand.c b/expand.c index b07893318382..623b180025ad 100644 --- a/expand.c +++ b/expand.c @@ -170,22 +170,6 @@ Float: expr->type = EXPR_FVALUE; } -static void warn_shift_count(struct expression *expr, struct symbol *ctype, long long count) -{ - if (count < 0) { - if (!Wshift_count_negative) - return; - warning(expr->pos, "shift count is negative (%lld)", count); - return; - } - if (ctype->type == SYM_NODE) - ctype = ctype->ctype.base_type; - - if (!Wshift_count_overflow) - return; - warning(expr->pos, "shift too big (%llu) for type %s", count, show_typename(ctype)); -} - /* Return true if constant shift size is valid */ static bool check_shift_count(struct expression *expr, struct expression *right) { @@ -194,8 +178,6 @@ static bool check_shift_count(struct expression *expr, struct expression *right) if (count >= 0 && count < ctype->bit_size) return true; - if (!conservative) - warn_shift_count(expr, ctype, count); return false; } diff --git a/linearize.c b/linearize.c index 4927468183b0..5a8e74970d98 100644 --- a/linearize.c +++ b/linearize.c @@ -2468,6 +2468,49 @@ static pseudo_t linearize_statement(struct entrypoint *ep, struct statement *stm return VOID; } +static void check_tainted_insn(struct instruction *insn) +{ + unsigned long long uval; + long long sval; + pseudo_t src2; + + switch (insn->opcode) { + case OP_DIVU: case OP_DIVS: + case OP_MODU: case OP_MODS: + if (insn->src2 == value_pseudo(0)) + warning(insn->pos, "divide by zero"); + break; + case OP_SHL: case OP_LSR: case OP_ASR: + src2 = insn->src2; + if (src2->type != PSEUDO_VAL) + break; + uval = src2->value; + if (uval < insn->size) + break; + sval = sign_extend(uval, insn->size); + if (Wshift_count_negative && sval < 0) + warning(insn->pos, "shift count is negative (%lld)", sval); + else if (Wshift_count_overflow) + warning(insn->pos, "shift too big (%llu) for type %s", uval, show_typename(insn->type)); + } +} + +/// +// issue warnings after all possible DCE +static void late_warnings(struct entrypoint *ep) +{ + struct basic_block *bb; + FOR_EACH_PTR(ep->bbs, bb) { + struct instruction *insn; + FOR_EACH_PTR(bb->insns, insn) { + if (!insn->bb) + continue; + if (insn->tainted) + check_tainted_insn(insn); + } END_FOR_EACH_PTR(insn); + } END_FOR_EACH_PTR(bb); +} + static struct entrypoint *linearize_fn(struct symbol *sym, struct symbol *base_type) { struct statement *stmt = base_type->stmt; @@ -2514,6 +2557,7 @@ static struct entrypoint *linearize_fn(struct symbol *sym, struct symbol *base_t add_one_insn(ep, ret); optimize(ep); + late_warnings(ep); return ep; } diff --git a/simplify.c b/simplify.c index 7850bcdc6069..f6b79685f439 100644 --- a/simplify.c +++ b/simplify.c @@ -754,28 +754,18 @@ static long long check_shift_count(struct instruction *insn, unsigned long long unsigned int size = insn->size; long long sval = uval; + if (insn->tainted) + return -1; + if (uval < size) return uval; + insn->tainted = 1; sval = sign_extend_safe(sval, size); sval = sign_extend_safe(sval, bits_in_int); if (sval < 0) insn->src2 = value_pseudo(sval); - if (insn->tainted) - return sval; - - if (sval < 0 && Wshift_count_negative) - warning(insn->pos, "shift count is negative (%lld)", sval); - if (sval > 0 && Wshift_count_overflow) { - struct symbol *ctype = insn->type; - const char *tname; - if (ctype->type == SYM_NODE) - ctype = ctype->ctype.base_type; - tname = show_typename(ctype); - warning(insn->pos, "shift too big (%llu) for type %s", sval, tname); - } - insn->tainted = 1; - return sval; + return -1; } static int simplify_shift(struct instruction *insn, pseudo_t pseudo, long long value) diff --git a/validation/expand/bad-shift.c b/validation/expand/bad-shift.c index 22c4341f1680..b68866c2b048 100644 --- a/validation/expand/bad-shift.c +++ b/validation/expand/bad-shift.c @@ -56,9 +56,9 @@ rneg: * check-output-end * * check-error-start -expand/bad-shift.c:5:18: warning: shift too big (32) for type int -expand/bad-shift.c:10:18: warning: shift count is negative (-1) -expand/bad-shift.c:15:18: warning: shift too big (32) for type int -expand/bad-shift.c:20:18: warning: shift count is negative (-1) +expand/bad-shift.c:5:21: warning: shift too big (32) for type int +expand/bad-shift.c:10:21: warning: shift count is negative (-1) +expand/bad-shift.c:15:21: warning: shift too big (32) for type int +expand/bad-shift.c:20:21: warning: shift count is negative (-1) * check-error-end */ diff --git a/validation/optim/shift-big.c b/validation/optim/shift-big.c index 84bcd2ce01a3..e7bf22fe36ff 100644 --- a/validation/optim/shift-big.c +++ b/validation/optim/shift-big.c @@ -50,13 +50,15 @@ lsr31: lsr32: .L8: <entry-point> - ret.32 $0 + lsr.32 %r14 <- %arg1, $32 + ret.32 %r14 lsr33: .L10: <entry-point> - ret.32 $0 + lsr.32 %r17 <- %arg1, $33 + ret.32 %r17 shl31: @@ -69,13 +71,15 @@ shl31: shl32: .L14: <entry-point> - ret.32 $0 + shl.32 %r23 <- %arg1, $32 + ret.32 %r23 shl33: .L16: <entry-point> - ret.32 $0 + shl.32 %r26 <- %arg1, $33 + ret.32 %r26 * check-output-end diff --git a/validation/shift-negative.c b/validation/shift-negative.c index fff5cf123dd6..6df02b18468f 100644 --- a/validation/shift-negative.c +++ b/validation/shift-negative.c @@ -9,8 +9,8 @@ unsigned int fo2(unsigned int a) { return a >> ((a & 0) ^ ~0); } * check-command: sparse -Wno-decl $file * * check-error-start -shift-negative.c:1:45: warning: shift count is negative (-1) -shift-negative.c:2:45: warning: shift count is negative (-1) +shift-negative.c:1:48: warning: shift count is negative (-1) +shift-negative.c:2:48: warning: shift count is negative (-1) shift-negative.c:4:59: warning: shift count is negative (-1) shift-negative.c:5:59: warning: shift count is negative (-1) * check-error-end diff --git a/validation/shift-undef-long.c b/validation/shift-undef-long.c index 326267436ec7..985fe4c4c595 100644 --- a/validation/shift-undef-long.c +++ b/validation/shift-undef-long.c @@ -13,9 +13,8 @@ static unsigned very_big_shift(unsigned int a) * check-command: sparse -m64 $file * * check-error-start -shift-undef-long.c:4:16: warning: shift too big (4294967295) for type unsigned int -shift-undef-long.c:5:16: warning: shift too big (4294967296) for type unsigned int -shift-undef-long.c:6:16: warning: shift too big (4294967296) for type unsigned int -shift-undef-long.c:7:16: warning: shift count is negative (-4294967296) +shift-undef-long.c:4:25: warning: shift count is negative (-1) +shift-undef-long.c:5:47: warning: shift too big (4294967296) for type unsigned int +shift-undef-long.c:7:20: warning: shift count is negative (-4294967296) * check-error-end */ diff --git a/validation/shift-undef.c b/validation/shift-undef.c index 613c6b95b113..0c7541e9ffd9 100644 --- a/validation/shift-undef.c +++ b/validation/shift-undef.c @@ -112,48 +112,24 @@ void hw_write(u32 val) * check-command: sparse -Wno-decl $file * * check-error-start -shift-undef.c:3:15: warning: shift too big (100) for type int -shift-undef.c:4:15: warning: shift too big (101) for type unsigned int -shift-undef.c:5:15: warning: shift too big (102) for type unsigned int -shift-undef.c:6:15: warning: shift count is negative (-1) -shift-undef.c:7:15: warning: shift count is negative (-2) -shift-undef.c:8:15: warning: shift count is negative (-3) -shift-undef.c:9:25: warning: shift too big (103) for type int -shift-undef.c:10:25: warning: shift too big (104) for type unsigned int -shift-undef.c:11:25: warning: shift too big (105) for type unsigned int -shift-undef.c:12:25: warning: shift count is negative (-4) -shift-undef.c:13:25: warning: shift count is negative (-5) -shift-undef.c:14:25: warning: shift count is negative (-6) -shift-undef.c:15:30: warning: shift too big (106) for type int -shift-undef.c:16:30: warning: shift too big (107) for type unsigned int -shift-undef.c:17:30: warning: shift too big (108) for type unsigned int -shift-undef.c:18:30: warning: shift count is negative (-7) -shift-undef.c:19:30: warning: shift count is negative (-8) -shift-undef.c:20:30: warning: shift count is negative (-9) +shift-undef.c:3:18: warning: shift too big (100) for type int +shift-undef.c:4:18: warning: shift too big (101) for type unsigned int +shift-undef.c:5:18: warning: shift too big (102) for type unsigned int +shift-undef.c:6:19: warning: shift count is negative (-1) +shift-undef.c:7:19: warning: shift count is negative (-2) +shift-undef.c:8:19: warning: shift count is negative (-3) shift-undef.c:21:29: warning: shift too big (109) for type int shift-undef.c:22:29: warning: shift too big (110) for type unsigned int shift-undef.c:23:29: warning: shift too big (111) for type unsigned int shift-undef.c:24:29: warning: shift count is negative (-10) shift-undef.c:25:29: warning: shift count is negative (-11) shift-undef.c:26:29: warning: shift count is negative (-12) -shift-undef.c:32:11: warning: shift too big (100) for type int -shift-undef.c:33:11: warning: shift too big (101) for type unsigned int -shift-undef.c:34:11: warning: shift too big (102) for type unsigned int -shift-undef.c:35:11: warning: shift count is negative (-1) -shift-undef.c:36:11: warning: shift too big (4294967294) for type unsigned int -shift-undef.c:37:11: warning: shift too big (4294967293) for type unsigned int -shift-undef.c:38:25: warning: shift too big (103) for type int -shift-undef.c:39:25: warning: shift too big (104) for type unsigned int -shift-undef.c:40:25: warning: shift too big (105) for type unsigned int -shift-undef.c:41:25: warning: shift count is negative (-4) -shift-undef.c:42:25: warning: shift too big (4294967291) for type unsigned int -shift-undef.c:43:25: warning: shift too big (4294967290) for type unsigned int -shift-undef.c:44:30: warning: shift too big (106) for type int -shift-undef.c:45:30: warning: shift too big (107) for type unsigned int -shift-undef.c:46:30: warning: shift too big (108) for type unsigned int -shift-undef.c:47:30: warning: shift count is negative (-7) -shift-undef.c:48:30: warning: shift too big (4294967288) for type unsigned int -shift-undef.c:49:30: warning: shift too big (4294967287) for type unsigned int +shift-undef.c:32:15: warning: shift too big (100) for type int +shift-undef.c:33:15: warning: shift too big (101) for type unsigned int +shift-undef.c:34:15: warning: shift too big (102) for type unsigned int +shift-undef.c:35:16: warning: shift count is negative (-1) +shift-undef.c:36:16: warning: shift count is negative (-2) +shift-undef.c:37:16: warning: shift count is negative (-3) shift-undef.c:50:26: warning: shift too big (109) for type int shift-undef.c:51:26: warning: shift too big (110) for type unsigned int shift-undef.c:52:26: warning: shift too big (111) for type unsigned int
Sparse complains when a shift amount is too big for the size of its operand or if it's negative. However, it does this even for expressions that are never evaluated. It's especially annoying in the kernel for type generic macros, for example the ones in arch/*/include/asm/cmpxchg.h So, remove all warnings done at expansion time and avoid any simplifications of such expressions. Same, at linearization and optimization time but in this case mark the instructions as 'tainted' to inhibit any further simplifications. Finally, at the end of the optimization phase, warn for the tainted instructions. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> --- expand.c | 18 ------------- linearize.c | 44 ++++++++++++++++++++++++++++++++ simplify.c | 20 ++++----------- validation/expand/bad-shift.c | 8 +++--- validation/optim/shift-big.c | 12 ++++++--- validation/shift-negative.c | 4 +-- validation/shift-undef-long.c | 7 +++-- validation/shift-undef.c | 48 +++++++++-------------------------- 8 files changed, 78 insertions(+), 83 deletions(-)