There were several existing optimizations that could change behavior in ways that violated the IEEE standard with regard to infinities, NaNs, or signed zeros. They are now gated behind a new #pragma optimize flag. This change allows intermediate code peephole optimization and common subexpression elimination to be used while maintaining IEEE conformance, but also keeps the rule-breaking optimizations available if desired.
See section F.9.2 of recent C standards for a discussion of how these optimizations violate IEEE rules.
This could give incorrect results for extended-to-comp conversions of certain negative integers like -2147483648 and -53021371269120. To get a fix for the same problem with regard to long long, ORCA/C should be linked with the latest version of ORCALib (which also works around some instances of the problem at run time). There are still other cases involving code in SysFloat that has not yet been patched.
Parameters declared directly with array types were already adjusted to pointer types in commit 5b953e2db0, but this code is needed for the remaining case where a typedef'd array type is used.
With these changes, 'array' parameters are treated for all purposes as really having pointer types, which is what the standards call for. This affects at least their size as reported by sizeof and the debugging information generated for them.
This allows the length of the string plus a few extra bytes used internally to be represented by a 16-bit integer. Since the size limit for memory allocations has been raised, there is no good reason to impose a shorter limit on strings.
Note that C99 and later specify a minimum translation limit for string constants of at least 4095 characters.
In the new implementation, variable arguments are not removed until the end of the function. This allows variable argument processing to be restarted, and it prevents the addresses of local variables from changing in the middle of the function. The requirement to turn off stack repair code around varargs functions is also removed.
This fixes#58.
When using such a string literal to initialize an array with automatic storage duration, the bytes after the first null would be set to 0, rather than the values from the string literal.
Here is an example program showing the problem:
#include <stdio.h>
int main(void) {
char s[] = "a\0b";
puts(s+2);
}
This affects field selection expressions where the left expressions is a struct/union assignment or a function call returning a struct or union. Such expressions should be accepted, but they were giving spurious errors.
The following program illustrates the problem:
struct S {int a,b;} x, y={2,3};
struct S f(void) {
struct S s = {7,8};
return s;
}
int main(void) {
return f().a + (x=y).b;
}
This gives a clearer pattern of matching ORCA/C's historical behavior if loose type checks are used, and the documentation is updated accordingly.
It also avoids breaking existing code that may be relying on the old behavior. I am aware of at least one place that does (conflicting declarations of InstallNetDriver in GNO's <gno/gno.h>).
These rules are used if loose type checks are disabled. They are intended to strictly implement the constraints in C17 sections 6.5.9 and 6.5.10.
This patch also fixes a bug where object pointer comparisons to "const void *" should be permitted but were not.
These will check that the prototypes (if present) match in number and types of arguments. This primarily affects operations on function pointers, since similar checks were already done elsewhere on function declarations themselves.
This causes an error to be produced when trying to assign to these fields, which was being allowed before. It is also necessary for correct behavior of _Generic in some cases.
This was not working because floating-point arguments are really passed in the extended format, but based on the wording in the C standard a type of "double" should still work for arguments passed with that type.
This fixes#29. (The bug report was valid only with respect to double, not float or long double.)
It could wind up storing garbage in the upper 8 bits of the destination, because it was not doing a proper 8-bit to 16-bit conversion.
This is an old bug, but the change in commit 95f5182442 caused it to be triggered in more cases, e.g. in the C7.5.1.1.CC test case.
Here is a case that could exhibit the bug even before that:
#pragma optimize 1
#include <stdio.h>
int main(void) {
int k[1];
int i = 0;
unsigned char uch = 'm';
k[i] = uch;
printf("%i\n", k[0]);
}
This applies to octal and hexadecimal sequences with out-of-range values, and also to unrecognized escape characters. The C standards say both of these cases are syntax/constraint violations requiring a diagnostic.
These are needed to correctly distinguish pointer types in _Generic. They should also be used for type compatibility checks in other contexts, but currently are not.
This also fixes a couple small problems related to type qualifiers:
*restrict was not allowed to appear after * in type-names
*volatile status was not properly recorded in sym files
Here is an example of using _Generic to distinguish pointer types based on the qualifiers of the pointed-to type:
#include <stdio.h>
#define f(e) _Generic((e),\
int * restrict *: 1,\
int * volatile const *: 2,\
int **: 3,\
default: 0)
#define g(e) _Generic((e),\
int *: 1,\
const int *: 2,\
volatile int *: 3,\
default: 0)
int main(void) {
int * restrict * p1;
int * volatile const * p2;
int * const * p3;
// should print "1 2 0 1"
printf("%i %i %i %i\n", f(p1), f(p2), f(p3), f((int * restrict *)0));
int *q1;
const int *q2;
volatile int *q3;
const volatile int *q4;
// should print "1 2 3 0"
printf("%i %i %i %i\n", g(q1), g(q2), g(q3), g(q4));
}
Here is an example of a problem resulting from volatile not being recorded in sym files (if a sym file was present, the read of x was lifted out of the loop):
#pragma optimize -1
static volatile int x;
#include <stdio.h>
int main(void) {
int y;
for (unsigned i = 0; i < 100; i++) {
y = x*2 + 7;
}
}
This is required by C99 and later, enabled by the availability of __func__.
This requires an updated assertion-printing function in ORCALib. Unfortunately, GNO has the assertion-printing function in its libc rather than in ORCALib, because it calls the GNO implementation of stdio. Therefore, we continue to use the old form under GNO for now, to maintain compatibility with its existing libc.
Previously, they were hard-coded as 60, but the clock tick frequency actually depends on the video mode. They now call a new library function that can detect the video mode and return the proper value.
This also makes CLOCKS_PER_SEC have the type clock_t, as C99 and later require.
Enumeration constants must have values representable as an int (i.e. 16-bit signed values, in ORCA/C), but errors were not being reported if code tried to use the values 0xFFFF8000 to 0xFFFFFFFF. This problem could also affect certain larger values of type unsigned long long. The issue stemmed from not properly accounting for whether the constant expression had a signed or unsigned type.
This sample code demonstrated the problem:
enum E {
a = 0xFFFFFFFF,
b = 0xFFFF8000,
y = 0x7FFFFFFFFFFFFFFFull,
z = 0x8000000000000000
};
This gives the name of the current function, as if the following definition appeared at the beginning of the function body:
static const char __func__[] = "function-name";
Stephen Heumann