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implement unsigned -> float casts

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amd64 lacks an instruction for this so it has to be implemented with
signed -> float casts:
 - Word casting is done by zero-extending the word to a long and then doing
   a regular signed cast.
 - Long casting is done by dividing by two with correct rounding if the
   highest bit is set and casting that to float, then adding
   1 to mantissa with integer addition
This commit is contained in:
Bor Grošelj Simić 2022-01-28 02:06:17 +01:00 • committed by Quentin Carbonneaux
parent b0d27d8a01
commit 74d022f975
6 changed files with 107 additions and 5 deletions
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49
test/fpcnv.ssa
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@ -17,13 +17,62 @@ function d $ftrunc(d %f) {
ret %rt
}
export
function s $wtos(w %w) {
@start
%rt =s uwtof %w
ret %rt
}
export
function d $wtod(w %w) {
@start
%rt =d uwtof %w
ret %rt
}
export
function s $ltos(l %l) {
@start
%rt =s ultof %l
ret %rt
}
export
function d $ltod(l %l) {
@start
%rt =d ultof %l
ret %rt
}
# >>> driver
# extern float fneg(float);
# extern double ftrunc(double);
#
# extern float wtos(unsigned int);
# extern double wtod(unsigned int);
# extern float ltos(long long unsigned int);
# extern double ltod(long long unsigned int);
#
# unsigned long long iin[] = { 0, 1, 16, 234987, 427386245, 0x7fff0000,
# 0xffff0000, 23602938196141, 72259248152500195, 9589010795705032704ull,
# 0xdcf5fbe299d0148aull, 0xffffffff00000000ull, -1 };
#
# int main() {
# int i;
#
# if (fneg(1.23f) != -1.23f) return 1;
# if (ftrunc(3.1415) != 3.0) return 2;
# if (ftrunc(-1.234) != -1.0) return 3;
#
# for (i=0; i<sizeof(iin)/sizeof(iin[0]); i++) {
# if (wtos(iin[i]) != (float) (unsigned int)iin[i])
# return 4;
# if (wtod(iin[i]) != (double)(unsigned int)iin[i])
# return 5;
# if (ltos(iin[i]) != (float) iin[i])
# return 6;
# if (ltod(iin[i]) != (double)iin[i])
# return 7;
# }
# return 0;
# }
# <<<