Gabe Black has submitted this change. (
https://gem5-review.googlesource.com/c/public/gem5/+/42361 )
Change subject: arch-x86: Use the new multiplication helpers in the mul
uops.
......................................................................
arch-x86: Use the new multiplication helpers in the mul uops.
Change-Id: Ib12b2e357fae19455a1a11dd890dda6602a6dc41
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/42361
Reviewed-by: Daniel Carvalho <oda...@yahoo.com.br>
Maintainer: Gabe Black <gabe.bl...@gmail.com>
Tested-by: kokoro <noreply+kok...@google.com>
---
M src/arch/x86/isa/includes.isa
M src/arch/x86/isa/microops/regop.isa
2 files changed, 37 insertions(+), 60 deletions(-)
Approvals:
Daniel Carvalho: Looks good to me, approved
Gabe Black: Looks good to me, approved
kokoro: Regressions pass
diff --git a/src/arch/x86/isa/includes.isa b/src/arch/x86/isa/includes.isa
index 71225ce..0136624 100644
--- a/src/arch/x86/isa/includes.isa
+++ b/src/arch/x86/isa/includes.isa
@@ -102,6 +102,7 @@
output exec {{
#include <cmath>
#include <limits>
+#include <tuple>
#include "arch/generic/debugfaults.hh"
#include "arch/x86/cpuid.hh"
@@ -112,6 +113,7 @@
#include "arch/x86/tlb.hh"
#include "base/compiler.hh"
#include "base/condcodes.hh"
+#include "base/logging.hh"
#include "cpu/base.hh"
#include "cpu/exetrace.hh"
#include "debug/X86.hh"
diff --git a/src/arch/x86/isa/microops/regop.isa
b/src/arch/x86/isa/microops/regop.isa
index fb0bea1..a634c48 100644
--- a/src/arch/x86/isa/microops/regop.isa
+++ b/src/arch/x86/isa/microops/regop.isa
@@ -584,43 +584,26 @@
class Mul1s(WrRegOp):
op_class = 'IntMultOp'
-
- # Multiply two values Aa and Bb where Aa = A << p + a, then
correct for
- # negative operands.
- # Aa * Bb
- # = (A << p + a) * (B << p + b)
- # = (A * B) << 2p + (A * b + a * B) << p + a * b
code = '''
- ProdLow = psrc1 * op2;
-
- int p = (dataSize * 8) / 2;
- uint64_t A = bits(psrc1, 2 * p - 1, p);
- uint64_t a = bits(psrc1, p - 1, 0);
- uint64_t B = bits<uint64_t>(op2, 2 * p - 1, p);
- uint64_t b = bits<uint64_t>(op2, p - 1, 0);
-
- uint64_t c1, c2; // Carry between place values.
- uint64_t ab = a * b, Ab = A * b, aB = a * B, AB = A * B;
-
- c1 = ab >> p;
-
- // Be careful to avoid overflow if p is large.
- if (p == 32) {
- c2 = (c1 >> 1) + (Ab >> 1) + (aB >> 1);
- c2 += ((c1 & 0x1) + (Ab & 0x1) + (aB & 0x1)) >> 1;
- c2 >>= (p - 1);
- } else {
- c2 = (c1 + Ab + aB) >> p;
+ int64_t hi, low;
+ switch (dataSize) {
+ case 8:
+ std::tie(hi, low) = mulSigned<int64_t>(psrc1, op2);
+ break;
+ case 4:
+ std::tie(hi, low) = mulSigned<int32_t>(psrc1, op2);
+ break;
+ case 2:
+ std::tie(hi, low) = mulSigned<int16_t>(psrc1, op2);
+ break;
+ case 1:
+ std::tie(hi, low) = mulSigned<int8_t>(psrc1, op2);
+ break;
+ default:
+ panic("Unrecognized data size %d.", dataSize);
}
-
- uint64_t hi = AB + c2;
-
- if (bits(psrc1, dataSize * 8 - 1))
- hi -= op2;
- if (bits(op2, dataSize * 8 - 1))
- hi -= psrc1;
-
ProdHi = hi;
+ ProdLow = low;
'''
flag_code = '''
if ((-ProdHi & mask(dataSize * 8)) !=
@@ -636,34 +619,26 @@
class Mul1u(WrRegOp):
op_class = 'IntMultOp'
- # Multiply two values Aa and Bb where Aa = A << p + a.
- # Aa * Bb
- # = (A << p + a) * (B << p + b)
- # = (A * B) << 2p + (A * b + a * B) << p + a * b
code = '''
- ProdLow = psrc1 * op2;
-
- int p = (dataSize * 8) / 2;
- uint64_t A = bits(psrc1, 2 * p - 1, p);
- uint64_t a = bits(psrc1, p - 1, 0);
- uint64_t B = bits<uint64_t>(op2, 2 * p - 1, p);
- uint64_t b = bits<uint64_t>(op2, p - 1, 0);
-
- uint64_t c1, c2; // Carry between place values.
- uint64_t ab = a * b, Ab = A * b, aB = a * B, AB = A * B;
-
- c1 = ab >> p;
-
- // Be careful to avoid overflow if p is large.
- if (p == 32) {
- c2 = (c1 >> 1) + (Ab >> 1) + (aB >> 1);
- c2 += ((c1 & 0x1) + (Ab & 0x1) + (aB & 0x1)) >> 1;
- c2 >>= (p - 1);
- } else {
- c2 = (c1 + Ab + aB) >> p;
+ uint64_t hi, low;
+ switch (dataSize) {
+ case 8:
+ std::tie(hi, low) = mulUnsigned<uint64_t>(psrc1, op2);
+ break;
+ case 4:
+ std::tie(hi, low) = mulUnsigned<uint32_t>(psrc1, op2);
+ break;
+ case 2:
+ std::tie(hi, low) = mulUnsigned<uint16_t>(psrc1, op2);
+ break;
+ case 1:
+ std::tie(hi, low) = mulUnsigned<uint8_t>(psrc1, op2);
+ break;
+ default:
+ panic("Unrecognized data size %d.", dataSize);
}
-
- ProdHi = AB + c2;
+ ProdHi = hi;
+ ProdLow = low;
'''
flag_code = '''
if (ProdHi) {
--
To view, visit https://gem5-review.googlesource.com/c/public/gem5/+/42361
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: Ib12b2e357fae19455a1a11dd890dda6602a6dc41
Gerrit-Change-Number: 42361
Gerrit-PatchSet: 11
Gerrit-Owner: Gabe Black <gabe.bl...@gmail.com>
Gerrit-Reviewer: Andreas Sandberg <andreas.sandb...@arm.com>
Gerrit-Reviewer: Daniel Carvalho <oda...@yahoo.com.br>
Gerrit-Reviewer: Gabe Black <gabe.bl...@gmail.com>
Gerrit-Reviewer: Giacomo Travaglini <giacomo.travagl...@arm.com>
Gerrit-Reviewer: Tong Shen <endlessr...@google.com>
Gerrit-Reviewer: kokoro <noreply+kok...@google.com>
Gerrit-MessageType: merged
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