GCC Bugzilla – Attachment 30937 Details for
Bug 53001
-Wfloat-conversion should be available to warn about floating point errors
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[patch]
Patch to add -Wfloat-conversion option against trunk
warn_float_patch_trunk_plus_casts.diff (text/plain), 13.31 KB, created by
Joshua Cogliati
on 2013-09-30 12:13:48 UTC
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Description:
Patch to add -Wfloat-conversion option against trunk
Filename:
MIME Type:
Creator:
Joshua Cogliati
Created:
2013-09-30 12:13:48 UTC
Size:
13.31 KB
patch
obsolete
>Index: gcc/c-family/c-common.c >=================================================================== >--- gcc/c-family/c-common.c (revision 202818) >+++ gcc/c-family/c-common.c (working copy) >@@ -2517,10 +2517,10 @@ > Function allows conversions between types of different signedness and > does not return true in that case. Function can produce signedness > warnings if PRODUCE_WARNS is true. */ >-bool >+enum conversion_safety > unsafe_conversion_p (tree type, tree expr, bool produce_warns) > { >- bool give_warning = false; >+ enum conversion_safety give_warning = SAFE_CONVERSION; /* is 0 or false */ > tree expr_type = TREE_TYPE (expr); > location_t loc = EXPR_LOC_OR_HERE (expr); > >@@ -2532,7 +2532,7 @@ > && TREE_CODE (type) == INTEGER_TYPE) > { > if (!real_isinteger (TREE_REAL_CST_PTR (expr), TYPE_MODE (expr_type))) >- give_warning = true; >+ give_warning = UNSAFE_REAL; > } > /* Warn for an integer constant that does not fit into integer type. */ > else if (TREE_CODE (expr_type) == INTEGER_TYPE >@@ -2553,7 +2553,7 @@ > " constant value to negative integer"); > } > else >- give_warning = true; >+ give_warning = UNSAFE_OTHER; > } > else if (TREE_CODE (type) == REAL_TYPE) > { >@@ -2562,7 +2562,7 @@ > { > REAL_VALUE_TYPE a = real_value_from_int_cst (0, expr); > if (!exact_real_truncate (TYPE_MODE (type), &a)) >- give_warning = true; >+ give_warning = UNSAFE_REAL; > } > /* Warn for a real constant that does not fit into a smaller > real type. */ >@@ -2571,7 +2571,7 @@ > { > REAL_VALUE_TYPE a = TREE_REAL_CST (expr); > if (!exact_real_truncate (TYPE_MODE (type), &a)) >- give_warning = true; >+ give_warning = UNSAFE_REAL; > } > } > } >@@ -2580,7 +2580,7 @@ > /* Warn for real types converted to integer types. */ > if (TREE_CODE (expr_type) == REAL_TYPE > && TREE_CODE (type) == INTEGER_TYPE) >- give_warning = true; >+ give_warning = UNSAFE_REAL; > > else if (TREE_CODE (expr_type) == INTEGER_TYPE > && TREE_CODE (type) == INTEGER_TYPE) >@@ -2618,7 +2618,7 @@ > && int_fits_type_p (op1, c_common_signed_type (type)) > && int_fits_type_p (op1, > c_common_unsigned_type (type)))) >- return false; >+ return SAFE_CONVERSION; > /* If constant is unsigned and fits in the target > type, then the result will also fit. */ > else if ((TREE_CODE (op0) == INTEGER_CST >@@ -2627,12 +2627,12 @@ > || (TREE_CODE (op1) == INTEGER_CST > && unsigned1 > && int_fits_type_p (op1, type))) >- return false; >+ return SAFE_CONVERSION; > } > } > /* Warn for integer types converted to smaller integer types. */ > if (TYPE_PRECISION (type) < TYPE_PRECISION (expr_type)) >- give_warning = true; >+ give_warning = UNSAFE_OTHER; > > /* When they are the same width but different signedness, > then the value may change. */ >@@ -2668,14 +2668,14 @@ > > if (!exact_real_truncate (TYPE_MODE (type), &real_low_bound) > || !exact_real_truncate (TYPE_MODE (type), &real_high_bound)) >- give_warning = true; >+ give_warning = UNSAFE_OTHER; > } > > /* Warn for real types converted to smaller real types. */ > else if (TREE_CODE (expr_type) == REAL_TYPE > && TREE_CODE (type) == REAL_TYPE > && TYPE_PRECISION (type) < TYPE_PRECISION (expr_type)) >- give_warning = true; >+ give_warning = UNSAFE_REAL; > } > > return give_warning; >@@ -2689,8 +2689,9 @@ > { > tree expr_type = TREE_TYPE (expr); > location_t loc = EXPR_LOC_OR_HERE (expr); >+ enum conversion_safety conversion_kind; > >- if (!warn_conversion && !warn_sign_conversion) >+ if (!warn_conversion && !warn_sign_conversion && !warn_float_conversion) > return; > > switch (TREE_CODE (expr)) >@@ -2717,10 +2718,19 @@ > > case REAL_CST: > case INTEGER_CST: >- if (unsafe_conversion_p (type, expr, true)) >- warning_at (loc, OPT_Wconversion, >- "conversion to %qT alters %qT constant value", >- type, expr_type); >+ conversion_kind = unsafe_conversion_p (type, expr, true); >+ if(conversion_kind == UNSAFE_REAL) >+ { >+ warning_at (loc, OPT_Wfloat_conversion, >+ "conversion to %qT alters %qT constant value", >+ type, expr_type); >+ } >+ else if(conversion_kind) >+ { >+ warning_at (loc, OPT_Wconversion, >+ "conversion to %qT alters %qT constant value", >+ type, expr_type); >+ } > return; > > case COND_EXPR: >@@ -2736,10 +2746,19 @@ > } > > default: /* 'expr' is not a constant. */ >- if (unsafe_conversion_p (type, expr, true)) >- warning_at (loc, OPT_Wconversion, >- "conversion to %qT from %qT may alter its value", >- type, expr_type); >+ conversion_kind = unsafe_conversion_p (type, expr, true); >+ if(conversion_kind == UNSAFE_REAL) >+ { >+ warning_at (loc, OPT_Wfloat_conversion, >+ "conversion to %qT from %qT may alter its value", >+ type, expr_type); >+ } >+ else if(conversion_kind) >+ { >+ warning_at (loc, OPT_Wconversion, >+ "conversion to %qT from %qT may alter its value", >+ type, expr_type); >+ } > } > } > >Index: gcc/c-family/c-common.h >=================================================================== >--- gcc/c-family/c-common.h (revision 202818) >+++ gcc/c-family/c-common.h (working copy) >@@ -685,6 +685,16 @@ > unsigned inlines_hidden : 1; /* True when -finlineshidden in effect. */ > }; > >+/* These variables are possible types of unsafe conversions. >+ SAFE_CONVERSION The conversion is safe >+ UNSAFE_OTHER Another type of conversion with problems >+ UNSAFE_SIGN Conversion between signed and unsigned integers >+ which are all warned about immediately, so this is unused >+ UNSAFE_REAL Conversions that reduce the precision of reals >+ including conversions from reals to integers >+ */ >+enum conversion_safety { SAFE_CONVERSION = 0, UNSAFE_OTHER, UNSAFE_SIGN, UNSAFE_REAL }; >+ > /* Global visibility options. */ > extern struct visibility_flags visibility_options; > >@@ -738,7 +748,7 @@ > extern tree c_common_signed_or_unsigned_type (int, tree); > extern void c_common_init_ts (void); > extern tree c_build_bitfield_integer_type (unsigned HOST_WIDE_INT, int); >-extern bool unsafe_conversion_p (tree, tree, bool); >+extern enum conversion_safety unsafe_conversion_p (tree, tree, bool); > extern bool decl_with_nonnull_addr_p (const_tree); > extern tree c_fully_fold (tree, bool, bool *); > extern tree decl_constant_value_for_optimization (tree); >Index: gcc/c-family/c-cppbuiltin.c >=================================================================== >--- gcc/c-family/c-cppbuiltin.c (revision 202818) >+++ gcc/c-family/c-cppbuiltin.c (working copy) >@@ -157,7 +157,7 @@ > p log10 b if b is a power of 10 > floor((p - 1) log10 b) otherwise > */ >- dig = (fmt->p - 1) * log10_b; >+ dig = (int)((fmt->p - 1) * log10_b); > sprintf (name, "__%s_DIG__", name_prefix); > builtin_define_with_int_value (name, dig); > >@@ -173,7 +173,7 @@ > > Recall that emin is negative, so the integer truncation calculates > the ceiling, not the floor, in this case. */ >- min_10_exp = (fmt->emin - 1) * log10_b; >+ min_10_exp = (int)((fmt->emin - 1) * log10_b); > sprintf (name, "__%s_MIN_10_EXP__", name_prefix); > sprintf (buf, "(%d)", min_10_exp); > builtin_define_with_value (name, buf, 0); >@@ -208,7 +208,7 @@ > Hand-waving aside, crunching all of the sets of constants above by hand > does not yield a case for which the first term is significant, which > in the end is all that matters. */ >- max_10_exp = fmt->emax * log10_b; >+ max_10_exp = (int)(fmt->emax * log10_b); > sprintf (name, "__%s_MAX_10_EXP__", name_prefix); > builtin_define_with_int_value (name, max_10_exp); > >@@ -224,14 +224,14 @@ > { > double d_decimal_dig > = 1 + (fmt->p < ldfmt->p ? ldfmt->p : fmt->p) * log10_b; >- decimal_dig = d_decimal_dig; >+ decimal_dig = (int)d_decimal_dig; > if (decimal_dig < d_decimal_dig) > decimal_dig++; > } > /* Similar, for this type rather than long double. */ > { > double type_d_decimal_dig = 1 + fmt->p * log10_b; >- type_decimal_dig = type_d_decimal_dig; >+ type_decimal_dig = (int)type_d_decimal_dig; > if (type_decimal_dig < type_d_decimal_dig) > type_decimal_dig++; > } >Index: gcc/c-family/c.opt >=================================================================== >--- gcc/c-family/c.opt (revision 202818) >+++ gcc/c-family/c.opt (working copy) >@@ -387,6 +387,10 @@ > C ObjC RejectNegative Warning Alias(Werror=, implicit-function-declaration) > This switch is deprecated; use -Werror=implicit-function-declaration instead > >+Wfloat-conversion >+C ObjC C++ ObjC++ Var(warn_float_conversion) LangEnabledBy(C ObjC C++ ObjC++,Wconversion) EnabledBy(Wextra) >+Warn for implicit type conversions that cause loss of floating point precision >+ > Wfloat-equal > C ObjC C++ ObjC++ Var(warn_float_equal) Warning > Warn if testing floating point numbers for equality >Index: gcc/doc/invoke.texi >=================================================================== >--- gcc/doc/invoke.texi (revision 202818) >+++ gcc/doc/invoke.texi (working copy) >@@ -263,7 +263,8 @@ > -Wpointer-arith -Wno-pointer-to-int-cast @gol > -Wredundant-decls -Wno-return-local-addr @gol > -Wreturn-type -Wsequence-point -Wshadow @gol >--Wsign-compare -Wsign-conversion -Wsizeof-pointer-memaccess @gol >+-Wsign-compare -Wsign-conversion -Wfloat-conversion @gol >+-Wsizeof-pointer-memaccess @gol > -Wstack-protector -Wstack-usage=@var{len} -Wstrict-aliasing @gol > -Wstrict-aliasing=n @gol -Wstrict-overflow -Wstrict-overflow=@var{n} @gol > -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{]} @gol >@@ -3334,6 +3335,7 @@ > -Wuninitialized @gol > -Wunused-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol > -Wunused-but-set-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol >+-Wfloat-conversion @gol > } > > The option @option{-Wextra} also prints warning messages for the >@@ -4553,6 +4555,14 @@ > integer variable. An explicit cast silences the warning. In C, this > option is enabled also by @option{-Wconversion}. > >+@item -Wfloat-conversion >+@opindex Wfloat-conversion >+@opindex Wno-float-conversion >+Warn for implicit conversions that reduce the precision of a real value. >+This includes conversions from real to integer, and from higher precision >+real to lower precision real values. This option is also enabled by >+@option{-Wconversion} or @option{-Wextra}. >+ > @item -Wsizeof-pointer-memaccess > @opindex Wsizeof-pointer-memaccess > @opindex Wno-sizeof-pointer-memaccess >Index: gcc/mcf.c >=================================================================== >--- gcc/mcf.c (revision 202818) >+++ gcc/mcf.c (working copy) >@@ -348,8 +348,8 @@ > > gcc_assert (x >= 0); > >- convertor.floatPart = x; >- convertor2.floatPart = x; >+ convertor.floatPart = (float)x; >+ convertor2.floatPart = (float)x; > convertor.intPart = MAGIC_CONST1 + (convertor.intPart >> 1); > convertor2.intPart = MAGIC_CONST2 - (convertor2.intPart >> 1); > >Index: gcc/predict.c >=================================================================== >--- gcc/predict.c (revision 202818) >+++ gcc/predict.c (working copy) >@@ -792,7 +792,7 @@ > /* If one probability is 0% and one 100%, avoid division by zero. */ > combined_probability = REG_BR_PROB_BASE / 2; > else >- combined_probability = (((double) combined_probability) * probability >+ combined_probability = (int)(((double) combined_probability) * probability > * REG_BR_PROB_BASE / d + 0.5); > } > >@@ -957,7 +957,7 @@ > /* If one probability is 0% and one 100%, avoid division by zero. */ > combined_probability = REG_BR_PROB_BASE / 2; > else >- combined_probability = (((double) combined_probability) >+ combined_probability = (int)(((double) combined_probability) > * probability > * REG_BR_PROB_BASE / d + 0.5); > } >Index: gcc/real.c >=================================================================== >--- gcc/real.c (revision 202818) >+++ gcc/real.c (working copy) >@@ -1550,14 +1550,14 @@ > } > > /* Bound the number of digits printed by the size of the representation. */ >- max_digits = SIGNIFICAND_BITS * M_LOG10_2; >+ max_digits = (int)(SIGNIFICAND_BITS * M_LOG10_2); > if (digits == 0 || digits > max_digits) > digits = max_digits; > > /* Estimate the decimal exponent, and compute the length of the string it > will print as. Be conservative and add one to account for possible > overflow or rounding error. */ >- dec_exp = REAL_EXP (&r) * M_LOG10_2; >+ dec_exp = (int)(REAL_EXP (&r) * M_LOG10_2); > for (max_digits = 1; dec_exp ; max_digits++) > dec_exp /= 10; > >@@ -2215,7 +2215,7 @@ > sign = r.sign; > r.sign = 0; > >- dec_exp = REAL_EXP (&r) * M_LOG10_2; >+ dec_exp = (int)(REAL_EXP (&r) * M_LOG10_2); > digits = dec_exp + 1; > gcc_assert ((digits + 2) < (int)buf_size); > >@@ -2818,7 +2818,7 @@ > than the number of bits required to hold the largest coefficient > of this mode. */ > double log2_10 = 3.3219281; >- return fmt->p * log2_10; >+ return (int)(fmt->p * log2_10); > } > return fmt->p; > } >Index: libcpp/symtab.c >=================================================================== >--- libcpp/symtab.c (revision 202818) >+++ libcpp/symtab.c (working copy) >@@ -287,7 +287,8 @@ > : (x) / (1024*1024)))) > #define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M')) > >- total_bytes = longest = sum_of_squares = nids = 0; >+ total_bytes = longest = nids = 0; >+ sum_of_squares = 0.0; > p = table->entries; > limit = p + table->nslots; > do
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