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Added comments that explain the unstable behavior of a test program.

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This commit is contained in:
Greg King 2015-06-30 09:00:28 -04:00
parent cd5935deb7
commit 5d4900e179
2 changed files with 17 additions and 10 deletions
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2
test/misc/Makefile
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@ -53,7 +53,7 @@ $(WORKDIR)/sitest%prg: sitest.c
-$(CL65) $(subst .,,$(*:.o%=-O%)) $(CC65FLAGS) $< -o $@
# -$(SIM65) $(SIM65FLAGS) $@
$(WORKDIR)/cc65141011%prg: cc65141011.c
@echo "FIXME: " $@ "currently will fail."
@echo "FIXME: " $@ "currently can fail."
$(CL65) $(subst .,,$(*:.o%=-O%)) $(CC65FLAGS) $< -o $@
-$(SIM65) $(SIM65FLAGS) $@

25
test/misc/cc65141011.c
View File

@ -1,4 +1,3 @@
/*
!!DESCRIPTION!! equality problem
!!ORIGIN!! Testsuite
@ -6,32 +5,37 @@
*/
/*
different result depending on whether constant is on left or right side
Different results, depending on whether constant is on left or right side.
The optimizer sometimes makes code that executes the right-side expression
as eight bits; but then, tests it against the left-side zero as 16 bits.
The high-byte is garbage; therefore, that test might, or might not, work.
It depends on the platform and the amount of optimization.
http://www.cc65.org/mailarchive/2014-10/11680.html
http://www.cc65.org/mailarchive/2014-10/11682.html
http://www.cc65.org/mailarchive/2014-10/11683.html
*/
#include <stdlib.h>
#include <stdio.h>
static unsigned char fails = 4;
static unsigned char bad[3], good[3];
int main(int n, char **args)
int main(void)
{
unsigned char joy_state = 0x7e;
unsigned a, b;
/* NOTE: somehow it only fails in the printf statement, the other stuff
/* NOTE: It fails in only the printf() statements, the other stuff
below works! */
printf("bad: %u\n", 0 == (joy_state & 1) );
printf("bad: %u, ", 0 == (joy_state & 1) );
printf("good: %u\n", (joy_state & 1) == 0 );
sprintf(bad, "%u", 0 == (joy_state & 1) );
sprintf(good, "%u", (joy_state & 1) == 0 );
printf("bad: %u\n", bad[0] - '0' );
printf("bad: %u, ", bad[0] - '0' );
printf("good: %u\n", good[0] - '0' );
fails -= bad[0] - '0';
@ -40,12 +44,15 @@ int main(int n, char **args)
if (0 == (joy_state & 1)) fails--;
if ((joy_state & 1) == 0) fails--;
printf("fails: %u\n", fails );
printf("failures: %u\n", fails );
/* The above printf() returns a value with a zero high-byte.
** Therefore, the next (broken) statement works (by accident).
*/
a = 0 == (joy_state & 1);
b = (joy_state & 1) == 0;
printf("a: %u\n", a );
printf("a: %u, ", a );
printf("b: %u\n", b );
return fails;