Hello Tony Gutierrez,
I'd like you to do a code review. Please visit
https://gem5-review.googlesource.com/c/public/gem5/+/29966
to review the following change.
Change subject: arch-gcn3: Fix VOP3 V_LDEXP_F64
......................................................................
arch-gcn3: Fix VOP3 V_LDEXP_F64
Replaced !std::isnormal with std::fpclassify because std::isnormal
is not specific enough. !std::isnormal was incorrectly catching
NaN, Inf, 0.0, and subnormals (aka denormals), where as it was only
suppose to catch subnormals.
The return value and error handling spec of std::ldexp listed on
cppreference.com appears to match up in nearly all cases after
making these changes. If std::ldexp handled subnormals as described
in the GCN3 2016 guide, we could have used vdst[lane] = std::ldexp
and not need to check for any corner cases.
Change-Id: I4c77af77c3b7798f86d40442610cef1296a28441
---
M src/arch/gcn3/insts/instructions.cc
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/src/arch/gcn3/insts/instructions.cc
b/src/arch/gcn3/insts/instructions.cc
index 2b992b1..302dad4 100644
--- a/src/arch/gcn3/insts/instructions.cc
+++ b/src/arch/gcn3/insts/instructions.cc
@@ -30282,10 +30282,11 @@
for (int lane = 0; lane < NumVecElemPerVecReg; ++lane) {
if (wf->execMask(lane)) {
- if (std::isnan(src1[lane]) || std::isinf(src1[lane])) {
+ if (std::isnan(src0[lane]) || std::isinf(src0[lane])) {
vdst[lane] = src0[lane];
- } else if (!std::isnormal(src1[lane])) {
- if (std::signbit(src1[lane])) {
+ } else if (std::fpclassify(src0[lane]) == FP_SUBNORMAL
+ || std::fpclassify(src0[lane]) == FP_ZERO) {
+ if (std::signbit(src0[lane])) {
vdst[lane] = -0.0;
} else {
vdst[lane] = +0.0;
--
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: I4c77af77c3b7798f86d40442610cef1296a28441
Gerrit-Change-Number: 29966
Gerrit-PatchSet: 1
Gerrit-Owner: Anthony Gutierrez <anthony.gutier...@amd.com>
Gerrit-Reviewer: Tony Gutierrez <anthony.gutier...@amd.com>
Gerrit-MessageType: newchange
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