riscv/rocket-chip
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make float_fix more conservative with replacement

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This commit is contained in:
Scott Beamer 2015-09-12 11:00:00 -07:00
parent a12cd13190
commit 3eed7ff238
1 changed files with 17 additions and 8 deletions
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25
csrc/float_fix.cc
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@ -6,13 +6,14 @@
#include <sstream>
// returns the bits in x[high:low] in the lowest positions
// returns the bits in x[high:low] in the lowest positions
uint64_t BitRange(uint64_t x, int high, int low) {
int high_gap = 64 - high;
return x << high_gap >> (low + high_gap);
}
// will "unrecode" a single float within a double
// uses magic numbers since can only handle float
// logic from berkeley-hardfloat/src/main/scala/recodedFloatNToFloatN.scala
uint64_t UnrecodeFloatFromDouble(uint64_t raw_input) {
@ -44,14 +45,18 @@ uint64_t UnrecodeFloatFromDouble(uint64_t raw_input) {
}
// checks if possibly recoded float inside double if upper 31 bits set
// checks if possibly recoded float inside double (upper 31 bits set)
bool NestedFloatPossible(uint64_t raw_input) {
const uint64_t mask = 0xfffffffe00000000;
return (raw_input & mask) == mask;
}
// best effort at replacing floats with unrecoded versions
// best effort at replacing the float writeback with unrecoded version
// will only replace if (all of following met):
// - log lines differ between rocket and lspike
// - log line contains a floating point inst
// - unrecoding the writeback data as a single float makes them match
void DiffAndFix(std::string rocket_filename, std::string lspike_filename) {
std::ifstream rocket_log(rocket_filename);
if (!rocket_log.is_open()) {
@ -66,16 +71,19 @@ void DiffAndFix(std::string rocket_filename, std::string lspike_filename) {
std::stringstream ss;
ss << std::hex;
std::string rocket_line, lspike_line;
while(getline(rocket_log,rocket_line) && getline(lspike_log,lspike_line)) {
if ((rocket_line != lspike_line) && // mismatch and includes fp inst
while (getline(rocket_log,rocket_line) && getline(lspike_log,lspike_line)) {
if ((rocket_line != lspike_line) &&
(rocket_line.find(" f") != std::string::npos)) {
std::string fp_wb_str = rocket_line.substr(40, 16);
std::string fixed_line(rocket_line.c_str()); // deep copy
std::string fp_wb_str = fixed_line.substr(40, 16);
uint64_t raw_fp;
ss << fp_wb_str;
ss >> raw_fp;
if (NestedFloatPossible(raw_fp)) {
snprintf(const_cast<char*>(rocket_line.data()) + 40, 17,
snprintf(const_cast<char*>(fixed_line.data()) + 40, 17,
"%016" PRIx64, UnrecodeFloatFromDouble(raw_fp));
if (fixed_line == lspike_line)
rocket_line = fixed_line;
}
}
printf("%s\n", rocket_line.c_str());
@ -86,10 +94,11 @@ void DiffAndFix(std::string rocket_filename, std::string lspike_filename) {
int main(int argc, char** argv) {
if (argc < 3) {
if (argc != 3) {
std::cout << "Usage: float_fix rocket_output lspike_output" << std::endl;
return -1;
}
// std::cout << NestedFloatPossible(0xf0f0f0ff0f000000) << std::endl;
DiffAndFix(std::string(argv[1]), std::string(argv[2]));
return 0;
}