https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107344
Bug ID: 107344
Summary: GCC/nvptx SESE region optimization
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Keywords: openacc
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: tschwinge at gcc dot gnu.org
CC: vries at gcc dot gnu.org
Target Milestone: ---
Target: nvptx
GCC/nvptx has a "SESE region optimization",
<https://inbox.sourceware.org/gcc-patches/564cc75d.3020...@acm.org>.
A "regression" has been introduced by recent commit
r13-3217-gc4d15dddf6b9eacb36f535807ad2ee364af46e04 "[PR107195] Set range to
zero when nonzero mask is 0":
UNSUPPORTED: libgomp.oacc-c/../libgomp.oacc-c-c++-common/nvptx-sese-1.c
-DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 -foffload=nvptx-none -O0
PASS: libgomp.oacc-c/../libgomp.oacc-c-c++-common/nvptx-sese-1.c
-DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 -foffload=nvptx-none -O2 (test
for excess errors)
PASS: libgomp.oacc-c/../libgomp.oacc-c-c++-common/nvptx-sese-1.c
-DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 -foffload=nvptx-none -O2
execution test
[-PASS:-]{+FAIL:+}
libgomp.oacc-c/../libgomp.oacc-c-c++-common/nvptx-sese-1.c
-DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 -foffload=nvptx-none -O2
scan-nvptx-none-offload-rtl-dump mach "SESE regions:.*
[0-9]+{[0-9]+->[0-9]+(\\.[0-9]+)+}"
Same for C++.
During investigation of that issue (which I suppose is just one random
example), I found that earlier code transformations/optimizations may inhibit
this "Neuter whole SESE regions" optimization.
It's unclear to me if this is an actual "problem", which optimization is "more
important".
