derek/gem5
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

arch-power: Add doubleword multiply instructions

Browse Source 
This introduces 128-bit multiplication helpers and adds
the following instructions.
  * Multiply Low Doubleword (mulld[o][.])
  * Multiply High Doubleword (mulhd[.])
  * Multiply High Doubleword Unsigned (mulhdu[.])

Change-Id: Id579c95468ffe5fe7b5164579ec1dfb18f0b3ab3
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/40903
Reviewed-by: Boris Shingarov <shingarov@labware.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
Sandipan Das
2021-02-06 17:17:45 +05:30
committed by Boris Shingarov
parent e2f275dce9
commit 930419bcb2
2 changed files with 85 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

43
src/arch/power/insts/integer.hh
View File

@@ -134,6 +134,49 @@ class IntArithOp : public IntOp
{
}
/**
* Compute 128-bit product of 64-bit unsigned integer multiplication
* based on https://stackoverflow.com/a/28904636
*/
inline std::tuple<uint64_t, uint64_t>
multiply(uint64_t ra, uint64_t rb) const
{
uint64_t plo, phi;
#if defined(__SIZEOF_INT128__)
__uint128_t prod = (__uint128_t)ra * rb;
plo = prod;
phi = prod >> 64;
#else
uint64_t ralo = (uint32_t)ra, rahi = ra >> 32;
uint64_t rblo = (uint32_t)rb, rbhi = rb >> 32;
uint64_t pp0 = ralo * rblo;
uint64_t pp1 = rahi * rblo;
uint64_t pp2 = ralo * rbhi;
uint64_t pp3 = rahi * rbhi;
uint64_t c = ((uint32_t)pp1) + ((uint32_t)pp2) + (pp0 >> 32);
phi = pp3 + (pp2 >> 32) + (pp1 >> 32) + (c >> 32);
plo = (c << 32) | ((uint32_t)pp0);
#endif
return std::make_tuple(plo, phi);
}
/* Compute 128-bit product of 64-bit signed integer multiplication */
inline std::tuple<uint64_t, int64_t>
multiply(int64_t ra, int64_t rb) const
{
uint64_t plo, phi;
#if defined(__SIZEOF_INT128__)
__int128_t prod = (__int128_t)ra * rb;
plo = prod;
phi = prod >> 64;
#else
std::tie(plo, phi) = multiply((uint64_t)ra, (uint64_t)rb);
if (rb < 0) phi -= (uint64_t)ra;
if (ra < 0) phi -= (uint64_t)rb;
#endif
return std::make_tuple(plo, (int64_t)phi);
}
std::string generateDisassembly(
Addr pc, const Loader::SymbolTable *symtab) const override;
};

58
src/arch/power/isa/decoder.isa
View File

@@ -483,10 +483,15 @@ decode PO default Unknown::unknown() {
// These instructions are of XO form with bit 21 as the OE bit.
default: decode XO_XO {
format IntSumOp {
8: subfc({{ ~Ra }}, {{ Rb }}, {{ 1 }}, true);
10: addc({{ Ra }}, {{ Rb }}, computeCA = true);
}
8: IntSumOp::subfc({{ ~Ra }}, {{ Rb }}, {{ 1 }}, true);
9: IntArithCheckRcOp::mulhdu({{
uint64_t res;
std::tie(std::ignore, res) = multiply(Ra, Rb);
Rt = res;
}});
10: IntSumOp::addc({{ Ra }}, {{ Rb }}, computeCA = true);
11: IntArithCheckRcOp::mulhwu({{
uint64_t res = (uint64_t)Ra_uw * Rb_uw;
@@ -496,11 +501,19 @@ decode PO default Unknown::unknown() {
40: IntSumOp::subf({{ ~Ra }}, {{ Rb }}, {{ 1 }});
75: IntArithCheckRcOp::mulhw({{
uint64_t res = (int64_t)Ra_sw * Rb_sw;
res = res >> 32;
Rt = res;
}});
format IntArithCheckRcOp {
73: mulhd({{
int64_t res;
std::tie(std::ignore, res) = multiply(Ra_sd, Rb_sd);
Rt = res;
}});
75: mulhw({{
uint64_t res = (int64_t)Ra_sw * Rb_sw;
res = res >> 32;
Rt = res;
}});
}
format IntSumOp {
104: neg({{ ~Ra }}, {{ 1 }});
@@ -512,13 +525,26 @@ decode PO default Unknown::unknown() {
234: addme({{ Ra }}, {{ -1ULL }}, {{ xer.ca }}, true);
}
235: IntArithCheckRcOp::mullw({{
int64_t res = (int64_t)Ra_sw * Rb_sw;
if (res != (int32_t)res) {
setOV = true;
}
Rt = res;
}}, true);
format IntArithCheckRcOp {
233: mulld({{
int64_t src1 = Ra_sd;
int64_t src2 = Rb_sd;
uint64_t res = src1 * src2;
std::tie(res, std::ignore) = multiply(src1, src2);
if (src1 != 0 && (int64_t)res / src1 != src2) {
setOV = true;
}
Rt = res;
}}, true);
235: mullw({{
int64_t res = (int64_t)Ra_sw * Rb_sw;
if (res != (int32_t)res) {
setOV = true;
}
Rt = res;
}}, true);
}
266: IntSumOp::add({{ Ra }}, {{ Rb }});