Re: [Patch] libgomp: Fix reverse-offload for GOMP_MAP_TO_PSET

[Tobias Burnus <tobias@codesourcery.com>]

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(Updated to fix -m32 build, otherwise unchanged.)

Any other comments?

On 07.02.23 23:51, Thomas Schwinge wrote:

> On 2023-02-06T12:52:11+0100, Tobias Burnus <tobias@codesourcery.com> wrote:
>> Seems as if I missed a GOMP_MAP_TO_PSET issue before. As nvptx is
>> XFAILed before, I only found it when testing on AMDGCN.
>>
>> For an array-descriptor 'ai' variable, omplower has:
>>     map(tofrom:MEM <integer(kind=4)[0:]> [(integer(kind=4)[0:] *)D.4346] [len: D.4345])
>>     map(to:ai [pointer set, len: 64])
>>     map(alloc:ai.data [pointer assign, bias: 0])
>>
>> The latter reaches GCC with the same address as 'ai' – i.e. the
>> one of the array descriptor. This then needs to be dereferenced
>> to get the address of the actual pointer.
>> The patch assumes (and asserts) that 'ai.data' is part of the 'ai'
>> such that I can use the host address of 'ai' to access the data.
>> If that's not guaranteed, we have to find another way (e.g. another
>> lookup). But so far it seems to hold and I have not seen a bias
>> other than 0.
>>
>> With that patch, libgomp.fortran/reverse-offload-5.f90 now works
>> with AMDGCN.
...
>> OK? Any comments to the attached patch?
...
> For x86_64-pc-linux-gnu '-m32' multilib:
...
> I suppose you'd do similar to what you already have a few lines above;
> that is, cast through 'uintptr_t':
>
>      devaddrs[j] = *(uint64_t *) (uintptr_t) (devaddrs[i] + sizes[j]);
Tobias
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libgomp: Fix reverse-offload for GOMP_MAP_TO_PSET

libgomp/
	* target.c (gomp_target_rev): Dereference ptr
	to get device address.
	* libgomp.fortran/reverse-offload-5.f90: Add test
	for unallocated allocatable.

 libgomp/target.c                                        | 8 +++++++-
 libgomp/testsuite/libgomp.fortran/reverse-offload-5.f90 | 6 ++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/libgomp/target.c b/libgomp/target.c
index c1682caea13..88f29908a08 100644
--- a/libgomp/target.c
+++ b/libgomp/target.c
@@ -3579,8 +3579,14 @@ gomp_target_rev (uint64_t fn_ptr, uint64_t mapnum, uint64_t devaddrs_ptr,
 		      }
 		    int k;
 		    n2 = NULL;
-		    cdata[i].present = true;
+		    /* Dereference devaddrs[j] to get the device addr.  */
+		    assert (devaddrs[j]-sizes[j] == cdata[i].devaddr);
+		    devaddrs[j] = *(uint64_t *) (uintptr_t) (devaddrs[i]
+							     + sizes[j]);
+		    cdata[j].present = true;
 		    cdata[j].devaddr = devaddrs[j];
+		    if (devaddrs[j] == 0)
+		      continue;
 		    k = gomp_map_cdata_lookup (cdata, devaddrs, kinds, sizes, j,
 					       devaddrs[j],
 					       devaddrs[j] + sizeof (void*),
diff --git a/libgomp/testsuite/libgomp.fortran/reverse-offload-5.f90 b/libgomp/testsuite/libgomp.fortran/reverse-offload-5.f90
index ef7eb7bdd52..16810eb47de 100644
--- a/libgomp/testsuite/libgomp.fortran/reverse-offload-5.f90
+++ b/libgomp/testsuite/libgomp.fortran/reverse-offload-5.f90
@@ -24,7 +24,7 @@ s2 = 55
 
 !$omp target map(to: A, A2, s1, s2)
 block
-  integer, allocatable :: ai(:), ai2(:), si1, si2
+  integer, allocatable :: ai(:), ai2(:), ai3(:), si1, si2, si3
 
   a = a * 2
   a2 = a2 * 3
@@ -38,7 +38,7 @@ block
 
   !$omp target device (ancestor:1)  &
   !$omp&       map(to: A, s1, ai, si1) map(always, to: a2, s2)  &
-  !$omp&       map(tofrom: ai2, si2)
+  !$omp&       map(tofrom: ai2, si2, ai3, si3)
     if (shared_mem) then
       if (any (a  /= 2 * [1,2,3,4])) stop 1
       if (s1 /= 4 * 532) stop 2
@@ -52,6 +52,7 @@ block
     if (any (ai2 /= [8,4,7,1])) stop 8
     if (si1 /= 64) stop 9
     if (si2 /= 765) stop 10
+    if (allocated (ai3) .or. allocated(si3)) stop 26
 
     a = a*3
     a2 = a2*7
@@ -80,6 +81,7 @@ block
   endif
   if (any (ai2 /= 21 * [8,4,7,1])) stop 24
   if (si2 /= 31 * 765) stop 25
+  if (allocated (ai3) .or. allocated(si3)) stop 27
 
   deallocate (ai, ai2, si1, si2)
 end block