Commit Graph

29 Commits

Author SHA1 Message Date
Stephen Heumann
e00d47aaaf Fix invalid memory access due to uninitialized pointer.
(From Kelvin Sherlock.)
2017-10-21 20:36:20 -05:00
Stephen Heumann
dce39a851e Peephole optimization: fix some places where an expression with side effects could be removed during optimization.
Without this fix, an expression of the form "0 * exp" would be reduced to simply "0" unless exp contained a function call; other side effects of exp (such as assignments or increments) would be removed.

A similar issue could occur with additions that use the same expression on both sides of the "+": after optimization, it would only be evaluated once. I think the cases addressed here are all undefined behavior under the C standards, so the old behavior wasn't technically wrong, but the new behavior is still less confusing.
2017-10-21 20:36:20 -05:00
Stephen Heumann
bd19465ab2 Fix so that reaching definitions are properly computed in loop optimization when there is unreachable code.
Specifically, this ensures that the depth-first numbering of basic blocks starts from 1, which is what ReachingDefinitions expects. Without this fix, reaching definitions wouldn't be correctly computed for functions that contain unreachable basic blocks (including the implicit one to return at the end). This could result in invalid hoisting of operations out of the loop.

This fixes the compca26.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
5ab7c7876b New optimization: Use unsigned rather than signed comparisons in some cases involving values that were originally unsigned bytes.
Specifically, convert signed word comparisons to unsigned if both sides were either unsigned byte values or non-negative constants. This is incorporated as part of intermediate code peephole optimization (bit 0).

This should alleviate some cases of performance regressions due to promoting char to int instead of unsigned int.
2017-10-21 20:36:20 -05:00
Stephen Heumann
ab51fc228d Allow string and double constants to appear within the operands of sizeof in a constant expression.
This fixes one of the problems in the compca08.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
3b9101ea30 Support += and -= operators on function parameters declared using array syntax (which are adjusted to have pointer type).
This fixes the compca25.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
c77bca8389 When arrays are declared using a typedef'd incomplete array type, don't fix the size for all arrays of that type based on the initializer of the first array using it.
This fixes the compca07.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
78493936bc When a bit-field is used within an lvalue expression but isn't what's being assigned to, don't erroneously assign to the bit-field instead.
This fixes the compca04.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
c788052b99 Allow dereferencing pointers to const struct or const union types.
This fixes the bug in the compca03.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
c4360c70a1 Allow arrays to be used (implicitly converted to pointers) as operands of && and ||, and the first operand of the ? : operator.
This fixes the bug in the compca02.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
2d6ae52d32 Fix bug where a preprocessing directive could be mis-evaluated if it occurred immediately after a use of a function-like macro.
This occurred because the code to handle the function-like macro use would read the following token, which could prompt processing of the following preprocessing directive in an inappropriate context.

The following example illustrates the problem (the error message would be printed):

#define A()
#define FOO 1
A()
#if !FOO
# error "shouldn't get here"
#endif
2017-10-21 20:36:20 -05:00
Stephen Heumann
97cca84713 When pointer arithmetic is used to initialize a global or static variable to point before the beginning of a string constant, initialize it to the value indicated by the pointer arithmetic.
Previously, such initializations would sometimes generate a garbage value pointing up to 65535 bytes beyond the start of the string constant. (This was due to a lack of sign-extension in the object code generation.)

Computing a pointer to before the start of an object invokes undefined behavior, so the previous behavior wasn't technically wrong, but it was unintuitive and served no useful purpose. The new behavior should at least be easier to understand and debug.
2017-10-21 20:36:20 -05:00
Stephen Heumann
d65cc99d9a Fix bug where globals or static variables initialized with the address-of operator and pointer arithmetic could get the wrong value.
For example, p would not be correctly initialized given the following global definitions:
int a = 4;
int *p = &a + 1; /* *(p-1) should be 4 */
2017-10-21 20:36:20 -05:00
Stephen Heumann
8e7f46dc99 Fix bug where globals or static variables initialized using pointer arithmetic on string constants could get the wrong value.
This fixes the compca16.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
0df71da4f1 Change Byte -> UByte conversion to use a "Word -> UByte" conversion, rather than introducing a new "Byte -> UByte" conversion.
The latter would require more changes to the code generator to understand it, whereas this approach doesn't require any changes. This is arguably less clean, but it matches other places where a byte value is subsequently operated on as a word without an explicit conversion, and the assembly instruction generated is the same.
2017-10-21 20:36:20 -05:00
Stephen Heumann
a39c06d268 Usual unary conversions (promotions) should promote unsigned char to int, not unsigned int.
This fixes the compca13.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
c28e48a54f Do an explicit conversion when converting from signed to unsigned byte values. This is needed because the value is held in a 16-bit register, sign-extended. The high 8 bits need to be cleared to convert to an unsigned byte.
This fixes the compca06.c test case.

Note that this generates inefficient code in the case of loading a signed byte value and then immediately casting it to unsigned (it first sign-extends the value, then masks off the high bits). This should be optimized, but at least the generated code is correct now.
2017-10-21 20:36:20 -05:00
Stephen Heumann
6bd0bef8c5 Fix bug causing wrong code generation for single-byte indirect local stores beyond the first 256 bytes of the stack frame.
This fixes the compca19.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
be91f1d1cc Disable an invalid optimization that would suppress stores of address values when they appeared to the left of the comma operator.
This fixes the compca22.c test case.

This optimization could be fixed and re-enabled, but to do so, you would have to check if the stored value is ever used subsequently, which is not information that's readily available in the peephole optimization pass. It would also be necessary to check if there are any stores to the same location within the right-side expression, which could kill the optimization.
2017-10-21 20:36:20 -05:00
Stephen Heumann
b9446a28a7 Don't do common subexpression elimination for indirect accesses where there is an intervening operation that may write to the same location.
This fixes the bug in the compca05.c test case.
2017-10-21 20:36:20 -05:00
Stephen Heumann
3225a54d76 Move ORCACDefs directory to root level. 2017-10-21 20:21:37 -05:00
Stephen Heumann
b74dafb913 Remove ORCALib binary and sources.
These can be maintained in the separate ORCALib repository.
2017-10-21 20:19:34 -05:00
Stephen Heumann
d8af5e54d4 Remove compiled cc binary and duplicate copy of release notes. 2017-10-21 20:14:22 -05:00
Stephen Heumann
408e2e4462 Add instructions for converting line endings.
The procedure for automatically converting them using Git filters is from Kelvin Sherlock, with some adjustments.
2017-10-21 20:09:08 -05:00
Stephen Heumann
46b6aa389f Change all text/source files to LF line endings. 2017-10-21 18:40:19 -05:00
Stephen Heumann
0c71404b58 Add remaining headers from ORCA/C 2.1.0. 2017-10-21 18:02:19 -05:00
mikew50
bc5e497395 Added a bin folder for compiled files from ORCA/C 2017-10-01 21:19:30 -06:00
mikew50
262afd5bbc ORCA/C changes in 2.1.1.B3, from the Opus ][ CD 2017-10-01 17:51:32 -06:00
mikew50
e72177985e ORCA/C 2.1.0 source from the Opus ][ CD 2017-10-01 17:47:47 -06:00