Kovacsics Róbert has uploaded this change for review. (
https://gem5-review.googlesource.com/11750
Change subject: mem: Fix off-by-one error in checkFunctional, and simplify
it
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mem: Fix off-by-one error in checkFunctional, and simplify it
There was an off-by-one error in the isRead() case, as `val_end` and
`func_end` pointed to the last byte to write to (not one past the last
byte), and thus `*_end - *_start` was not the length of the data to
memcpy.
This was correct in the case of
val_start >= func_start && val_end <= func_end
where `overlap_size = size`, but if it were (as the other cases
suggest) `overlap_size = val_end - val_start`, then it would also be
off by one.
Also, the isWrite() case catered for this.
I simplified the four ifs into one case which uses min/max (this is
how I spotted the inconsistency).
Change-Id: Ib5c5da084652e752f6baf1eec56b51b4f0f5c95c
---
M src/mem/packet.cc
1 file changed, 27 insertions(+), 78 deletions(-)
diff --git a/src/mem/packet.cc b/src/mem/packet.cc
index 7a81cdb..684db5b 100644
--- a/src/mem/packet.cc
+++ b/src/mem/packet.cc
@@ -251,94 +251,43 @@
return false;
}
- // offset of functional request into supplied value (could be
- // negative if partial overlap)
- int offset = func_start - val_start;
+ int val_offset = max(func_start - val_start, (Addr)0);
+ int func_offset = max(val_start - func_start, (Addr)0);
+ int overlap_size = min(val_end, func_end)+1 -
+ max(val_start, func_start);
if (isRead()) {
- if (func_start >= val_start && func_end <= val_end) {
- memcpy(getPtr<uint8_t>(), _data + offset, getSize());
- if (bytesValid.empty())
- bytesValid.resize(getSize(), true);
- // complete overlap, and as the current packet is a read
- // we are done
- return true;
- } else {
- // Offsets and sizes to copy in case of partial overlap
- int func_offset;
- int val_offset;
- int overlap_size;
+ memcpy(getPtr<uint8_t>() + func_offset,
+ _data + val_offset,
+ overlap_size);
- // calculate offsets and copy sizes for the two byte arrays
- if (val_start < func_start && val_end <= func_end) {
- // the one we are checking against starts before and
- // ends before or the same
- val_offset = func_start - val_start;
- func_offset = 0;
- overlap_size = val_end - func_start;
- } else if (val_start >= func_start && val_end > func_end) {
- // the one we are checking against starts after or the
- // same, and ends after
- val_offset = 0;
- func_offset = val_start - func_start;
- overlap_size = func_end - val_start;
- } else if (val_start >= func_start && val_end <= func_end) {
- // the one we are checking against is completely
- // subsumed in the current packet, possibly starting
- // and ending at the same address
- val_offset = 0;
- func_offset = val_start - func_start;
- overlap_size = size;
- } else if (val_start < func_start && val_end > func_end) {
- // the current packet is completely subsumed in the
- // one we are checking against
- val_offset = func_start - val_start;
- func_offset = 0;
- overlap_size = func_end - func_start;
- } else {
- panic("Missed a case for checkFunctional with "
- " %s 0x%x size %d, against 0x%x size %d\n",
- cmdString(), getAddr(), getSize(), addr, size);
- }
+ // initialise the tracking of valid bytes if we have not
+ // used it already
+ if (bytesValid.empty())
+ bytesValid.resize(getSize(), false);
- // copy partial data into the packet's data array
- uint8_t *dest = getPtr<uint8_t>() + func_offset;
- uint8_t *src = _data + val_offset;
- memcpy(dest, src, overlap_size);
+ // track if we are done filling the functional access
+ bool all_bytes_valid = true;
- // initialise the tracking of valid bytes if we have not
- // used it already
- if (bytesValid.empty())
- bytesValid.resize(getSize(), false);
+ int i = 0;
- // track if we are done filling the functional access
- bool all_bytes_valid = true;
+ // check up to func_offset
+ for (; all_bytes_valid && i < func_offset; ++i)
+ all_bytes_valid &= bytesValid[i];
- int i = 0;
+ // update the valid bytes
+ for (i = func_offset; i < func_offset + overlap_size; ++i)
+ bytesValid[i] = true;
- // check up to func_offset
- for (; all_bytes_valid && i < func_offset; ++i)
- all_bytes_valid &= bytesValid[i];
+ // check the bit after the update we just made
+ for (; all_bytes_valid && i < getSize(); ++i)
+ all_bytes_valid &= bytesValid[i];
- // update the valid bytes
- for (i = func_offset; i < func_offset + overlap_size; ++i)
- bytesValid[i] = true;
-
- // check the bit after the update we just made
- for (; all_bytes_valid && i < getSize(); ++i)
- all_bytes_valid &= bytesValid[i];
-
- return all_bytes_valid;
- }
+ return all_bytes_valid;
} else if (isWrite()) {
- if (offset >= 0) {
- memcpy(_data + offset, getConstPtr<uint8_t>(),
- (min(func_end, val_end) - func_start) + 1);
- } else {
- // val_start > func_start
- memcpy(_data, getConstPtr<uint8_t>() - offset,
- (min(func_end, val_end) - val_start) + 1);
- }
+ memcpy(_data + val_offset,
+ getConstPtr<uint8_t>() + func_offset,
+ size);
} else {
panic("Don't know how to handle command %s\n", cmdString());
}
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-Change-Id: Ib5c5da084652e752f6baf1eec56b51b4f0f5c95c
Gerrit-Change-Number: 11750
Gerrit-PatchSet: 1
Gerrit-Owner: Kovacsics Róbert <[email protected]>
Gerrit-MessageType: newchange
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