mirrors/yosys
3
0
Fork 0
mirror of https://github.com/YosysHQ/yosys synced 2026-03-02 03:36:56 +00:00
Code Activity

symfpu: Add -compare mode

Browse source 
Also `min` and `max` ops.  RISC-V uses IEEE 754-2019 semantics where `min(+0,-0) == -0` and `max(+0,-0) == +0` so we do the same here.  We could make it optional, but as I understand it the newer behavior is still backwards compatible (since previously it was valid to have selected either).
This commit is contained in:
Krystine Sherwin 2026-02-27 12:55:02 +13:00
parent 341cd563bd
commit f71544a147
No known key found for this signature in database
1 changed files with 46 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

50
passes/cmds/symfpu.cc
View file

@ -30,6 +30,7 @@
#include "libs/symfpu/core/sqrt.h"
#include "libs/symfpu/core/unpackedFloat.h"
#include "libs/symfpu/core/classify.h"
#include "libs/symfpu/core/compare.h"
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
@ -417,6 +418,8 @@ struct SymFpuPass : public Pass {
"sub | two input subtraction | o = a-b\n"
"mul | two input multiplication | o = a*b\n"
"div | two input divison | o = a/b\n"
"min | two input minimum | o = min(a,b)\n"
"max | two input maximum | o = max(a,b)\n"
"muladd | three input fused multiple-add | o = (a*b)+c\n"
);
@ -441,6 +444,13 @@ struct SymFpuPass : public Pass {
"isPositive, isNegative, and isFinite."
);
content_root->usage("symfpu -compare [size]");
content_root->paragraph(
"Generates netlist for floating point comparison of inputs a and b. Outputs "
"6 single-bit signals, smtlibEqual, ieee754Equal, lessThan, lessThanOrEqual, "
"sNV (invalid signaling comparison), and qNV (invalid quiet comparison)."
);
return true;
}
void execute(std::vector<std::string> args, RTLIL::Design *design) override
@ -449,7 +459,7 @@ struct SymFpuPass : public Pass {
int eb = 8, sb = 24;
string op = "mul", rounding = "DYN";
int inputs = 2;
bool classify = false;
bool classify = false, compare = false;
log_header(design, "Executing SYMFPU pass.\n");
size_t argidx;
@ -472,6 +482,8 @@ struct SymFpuPass : public Pass {
|| op.compare("mul") == 0
|| op.compare("altdiv") == 0 // currently undocumented
|| op.compare("alt2div") == 0 // currently undocumented
|| op.compare("min") == 0
|| op.compare("max") == 0
|| op.compare("div") == 0)
inputs = 2;
else if (op.compare("muladd") == 0)
@ -489,15 +501,31 @@ struct SymFpuPass : public Pass {
classify = true;
continue;
}
if (args[argidx] == "-compare") {
compare = true;
continue;
}
break;
}
extra_args(args, argidx, design);
if (classify) {
if (rounding.compare("DYN") != 0)
if (compare && classify)
log_cmd_error("-classify and -compare flags are incompatible.\n");
if (rounding.compare("DYN") != 0) {
if (compare)
log_cmd_error("symfpu -compare does not support rounding modes.\n");
if (classify)
log_cmd_error("symfpu -classify does not support rounding modes.\n");
if (op.compare("mul") != 0)
if (op.compare("min") == 0 || op.compare("max") == 0)
log_cmd_error("min/max operations do not support rounding modes.\n");
}
if (op.compare("mul") != 0) {
if (compare)
log_cmd_error("symfpu -compare does not support operator selection.\n");
if (classify)
log_cmd_error("symfpu -classify does not support operator selection.\n");
}
@ -535,6 +563,15 @@ struct SymFpuPass : public Pass {
output_prop(ID(isPositive), symfpu::isPositive(format, a));
output_prop(ID(isNegative), symfpu::isNegative(format, a));
output_prop(ID(isFinite), symfpu::isFinite(format, a));
} else if (compare) {
auto b_bv = input_ubv(ID(b), eb+sb);
uf b = symfpu::unpack<rtlil_traits>(format, b_bv);
output_prop(ID(smtlibEqual), symfpu::smtlibEqual(format, a, b));
output_prop(ID(ieee754Equal), symfpu::ieee754Equal(format, a, b));
output_prop(ID(lessThan), symfpu::lessThan(format, a, b));
output_prop(ID(lessThanOrEqual), symfpu::lessThanOrEqual(format, a, b));
output_prop(ID(sNV), a.getNaN() || b.getNaN());
output_prop(ID(qNV), (a.getNaN() && is_sNaN(a_bv, sb)) || (b.getNaN() && is_sNaN(b_bv, sb)));
} else {
auto b_bv = input_ubv(ID(b), eb+sb);
auto c_bv = input_ubv(ID(c), eb+sb);
@ -575,6 +612,11 @@ struct SymFpuPass : public Pass {
return symfpu::falseDivide_flagged(format, rounding_mode, a, b, prop(false));
else if (op.compare("altsqrt") == 0)
return symfpu::falseSqrt_flagged(format, rounding_mode, a);
else if (op.compare("min") == 0)
// setting zeroCase=a.getSign() makes +0 > -0, as per IEEE 754-2019
return uf_flagged(symfpu::min(format, a, b, a.getSign()));
else if (op.compare("max") == 0)
return uf_flagged(symfpu::max(format, a, b, a.getSign()));
else
log_abort();
};