From bac2d8a246892334e24dfa7d62be0cd0648c5606 Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <tschwinge@baylibre.com>
Date: Tue, 25 Feb 2025 22:31:25 +0100
Subject: [PATCH] nvptx: Build libgfortran with '-mfake-ptx-alloca' [PR107635]
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As of recent commit 8bf0ee8d62b8a08e808344d31354ab713157e15d
"Fortran: Add transfer_between_remotes [PR107635]", we've got 'alloca' usage
in 'libgfortran/caf/single.c:_gfortran_caf_transfer_between_remotes', and
the libgfortran target library fails to build for legacy configurations where
PTX 'alloca' is not available:
../../../../source-gcc/libgfortran/caf/single.c: In function ‘_gfortran_caf_transfer_between_remotes’:
../../../../source-gcc/libgfortran/caf/single.c:675:23: sorry, unimplemented: dynamic stack allocation not supported
675 | transfer_desc = __builtin_alloca (desc_size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../../../source-gcc/libgfortran/caf/single.c:680:20: sorry, unimplemented: dynamic stack allocation not supported
680 | transfer_ptr = __builtin_alloca (*opt_dst_charlen * src_size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
make[6]: *** [Makefile:4675: caf/single.lo] Error 1
With '-mfake-ptx-alloca', libgfortran again succeeds to build, and compared
to before, we've got only a small number of regressions due to nvptx 'ld'
complaining about 'unresolved symbol __GCC_nvptx__PTX_alloca_not_supported':
[-PASS:-]{+FAIL:+} gfortran.dg/coarray/codimension_2.f90 -fcoarray=lib -O2 -lcaf_single (test for excess errors)
[-PASS:-]{+FAIL:+} gfortran.dg/coarray/event_4.f08 -fcoarray=lib -O2 -lcaf_single (test for excess errors)
[-PASS:-]{+UNRESOLVED:+} gfortran.dg/coarray/event_4.f08 -fcoarray=lib -O2 -lcaf_single [-execution test-]{+compilation failed to produce executable+}
[-PASS:-]{+FAIL:+} gfortran.dg/coarray/fail_image_2.f08 -fcoarray=lib -O2 -lcaf_single (test for excess errors)
[-PASS:-]{+UNRESOLVED:+} gfortran.dg/coarray/fail_image_2.f08 -fcoarray=lib -O2 -lcaf_single [-execution test-]{+compilation failed to produce executable+}
[-PASS:-]{+FAIL:+} gfortran.dg/coarray/proc_pointer_assign_1.f90 -fcoarray=lib -O2 -lcaf_single (test for excess errors)
[-PASS:-]{+UNRESOLVED:+} gfortran.dg/coarray/proc_pointer_assign_1.f90 -fcoarray=lib -O2 -lcaf_single [-execution test-]{+compilation failed to produce executable+}
[-PASS:-]{+FAIL:+} gfortran.dg/coarray_43.f90 -O (test for excess errors)
That's acceptable for such legacy PTX configurations.
PR target/107635
libgfortran/
* config/t-nvptx: New.
* configure.host [nvptx] (tmake_file): Add it.
---
libgfortran/config/t-nvptx | 2 ++
libgfortran/configure.host | 4 ++++
2 files changed, 6 insertions(+)
create mode 100644 libgfortran/config/t-nvptx
diff --git a/libgfortran/config/t-nvptx b/libgfortran/config/t-nvptx
new file mode 100644
index 000000000000..88bd6eee9826
--- /dev/null
+++ b/libgfortran/config/t-nvptx
@@ -0,0 +1,2 @@
+# Re 'alloca' usage in '../caf/single.c':
+AM_CFLAGS += -mfake-ptx-alloca
diff --git a/libgfortran/configure.host b/libgfortran/configure.host
index 291188d19c29..9abd40f511ae 100644
--- a/libgfortran/configure.host
+++ b/libgfortran/configure.host
@@ -91,6 +91,10 @@ case "${target}" in
tmake_file="t-aix"
;;
+ nvptx-*-none)
+ tmake_file="$tmake_file t-nvptx"
+ ;;
+
*)
;;
--
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