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misc: Fixed null-pointer arithmetic error

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Doing arithmetic on a null pointer is undefined behavior in C/C++. Clang
compilers complain when this occurs. As this MACRO is used twice, and
does nothing important, it has been removed in favor of a more simple
solution. A comment has been added explaining the MACRO's removal.

Change-Id: I42d9356179ee0fa5cb20f827af34bb11780ad1a9
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/29534
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
Bobby R. Bruce
2020-05-27 03:46:07 -07:00
parent a8fb7a0c1d
commit fc856981d8
2 changed files with 15 additions and 7 deletions
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5
src/dev/hsa/hsa_packet_processor.hh
View File

@@ -52,11 +52,6 @@
// HSA runtime supports only 5 signals per barrier packet
#define NumSignalsPerBarrier 5
// This define is copied from hsa runtime (libhsakmt/src/libhsakmt.h)
// This is the mapping function used by runtime for mapping
// queueID to dooorbell address
#define VOID_PTR_ADD32(ptr,n) (void*)((uint32_t*)(ptr) + n)/*ptr + offset*/
class HSADevice;
class HWScheduler;

17
src/dev/hsa/hw_scheduler.cc
View File

@@ -90,7 +90,12 @@ HWScheduler::registerNewQueue(uint64_t hostReadIndexPointer,
// Map queue ID to doorbell.
// We are only using offset to pio base address as doorbell
// We use the same mapping function used by hsa runtime to do this mapping
Addr db_offset = (Addr)(VOID_PTR_ADD32(0, queue_id));
//
// Originally
// #define VOID_PTR_ADD32(ptr,n) \
// (void*)((uint32_t*)(ptr) + n)/*ptr + offset*/
// (Addr)VOID_PTR_ADD32(0, queue_id)
Addr db_offset = queue_id;
if (dbMap.find(db_offset) != dbMap.end()) {
panic("Creating an already existing queue (queueID %d)", queue_id);
}
@@ -333,7 +338,15 @@ HWScheduler::write(Addr db_addr, uint32_t doorbell_reg)
void
HWScheduler::unregisterQueue(uint64_t queue_id)
{
Addr db_offset = (Addr)(VOID_PTR_ADD32(0, queue_id));
// Pointer arithmetic on a null pointer is undefined behavior. Clang
// compilers therefore complain if the following reads:
// `(Addr)(VOID_PRT_ADD32(0, queue_id))`
//
// Originally
// #define VOID_PTR_ADD32(ptr,n) \
// (void*)((uint32_t*)(ptr) + n)/*ptr + offset*/
// (Addr)VOID_PTR_ADD32(0, queue_id)
Addr db_offset = queue_id;
auto dbmap_iter = dbMap.find(db_offset);
if (dbmap_iter == dbMap.end()) {
panic("Destroying a non-existing queue (db_offset %x)",