Boris Shingarov has submitted this change. (
https://gem5-review.googlesource.com/c/public/gem5/+/40903 )
Change subject: arch-power: Add doubleword multiply instructions
......................................................................
arch-power: Add doubleword multiply instructions
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 <[email protected]>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/40903
Reviewed-by: Boris Shingarov <[email protected]>
Maintainer: Jason Lowe-Power <[email protected]>
Tested-by: kokoro <[email protected]>
---
M src/arch/power/insts/integer.hh
M src/arch/power/isa/decoder.isa
2 files changed, 85 insertions(+), 16 deletions(-)
Approvals:
Boris Shingarov: Looks good to me, approved
Jason Lowe-Power: Looks good to me, approved
kokoro: Regressions pass
diff --git a/src/arch/power/insts/integer.hh
b/src/arch/power/insts/integer.hh
index aafbbec..95f1598 100644
--- a/src/arch/power/insts/integer.hh
+++ b/src/arch/power/insts/integer.hh
@@ -134,6 +134,49 @@
{
}
+ /**
+ * 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;
};
diff --git a/src/arch/power/isa/decoder.isa b/src/arch/power/isa/decoder.isa
index beacd6f..b4c90fc 100644
--- a/src/arch/power/isa/decoder.isa
+++ b/src/arch/power/isa/decoder.isa
@@ -483,10 +483,15 @@
// 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 @@
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 @@
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 }});
6 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the
submitted one.
--
To view, visit https://gem5-review.googlesource.com/c/public/gem5/+/40903
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: Id579c95468ffe5fe7b5164579ec1dfb18f0b3ab3
Gerrit-Change-Number: 40903
Gerrit-PatchSet: 8
Gerrit-Owner: Sandipan Das <[email protected]>
Gerrit-Reviewer: Boris Shingarov <[email protected]>
Gerrit-Reviewer: Jason Lowe-Power <[email protected]>
Gerrit-Reviewer: kokoro <[email protected]>
Gerrit-MessageType: merged
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