[gcc/devel/omp/gcc-14] openmp: Add -foffload-memory

[Paul-Antoine Arras]

https://gcc.gnu.org/g:33f539fa1466fa2ac21091c35b81d00741adc85f

commit 33f539fa1466fa2ac21091c35b81d00741adc85f
Author: Andrew Stubbs <ams@codesourcery.com>
Date:   Mon Apr 22 18:07:00 2024 +0200

    openmp: Add -foffload-memory
    
    Add a new option.  It's inactive until I add some follow-up patches.
    
    gcc/ChangeLog:
    
            * common.opt: Add -foffload-memory and its enum values.
            * coretypes.h (enum offload_memory): New.

Diff:
---
 gcc/ChangeLog.omp   |  6 ++++++
 gcc/common.opt      | 16 ++++++++++++++++
 gcc/coretypes.h     |  7 +++++++
 gcc/doc/invoke.texi | 16 +++++++++++++++-
 4 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/gcc/ChangeLog.omp b/gcc/ChangeLog.omp
index 52306a5d516..f2bf2eb5b50 100644
--- a/gcc/ChangeLog.omp
+++ b/gcc/ChangeLog.omp
@@ -1,3 +1,9 @@
+2023-08-23  Andrew Stubbs  <ams@codesourcery.com>
+
+	* common.opt: Add -foffload-memory and its enum values.
+	* coretypes.h (enum offload_memory): New.
+	* doc/invoke.texi: Document -foffload-memory.
+
 2022-10-19  Tobias Burnus  <tobias@codesourcery.com>
 
 	* omp-expand.cc (expand_omp_target): Fix OpenACC in case there
diff --git a/gcc/common.opt b/gcc/common.opt
index ad348844775..e19c4ef1166 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2339,6 +2339,22 @@ Enum(offload_abi) String(ilp32) Value(OFFLOAD_ABI_ILP32)
 EnumValue
 Enum(offload_abi) String(lp64) Value(OFFLOAD_ABI_LP64)
 
+foffload-memory=
+Common Joined RejectNegative Enum(offload_memory) Var(flag_offload_memory) Init(OFFLOAD_MEMORY_NONE)
+-foffload-memory=[none|unified|pinned]	Use an offload memory optimization.
+
+Enum
+Name(offload_memory) Type(enum offload_memory) UnknownError(Unknown offload memory option %qs)
+
+EnumValue
+Enum(offload_memory) String(none) Value(OFFLOAD_MEMORY_NONE)
+
+EnumValue
+Enum(offload_memory) String(unified) Value(OFFLOAD_MEMORY_UNIFIED)
+
+EnumValue
+Enum(offload_memory) String(pinned) Value(OFFLOAD_MEMORY_PINNED)
+
 fomit-frame-pointer
 Common Var(flag_omit_frame_pointer) Optimization
 When possible do not generate stack frames.
diff --git a/gcc/coretypes.h b/gcc/coretypes.h
index 1ac6f0abea3..938cfa93753 100644
--- a/gcc/coretypes.h
+++ b/gcc/coretypes.h
@@ -218,6 +218,13 @@ enum offload_abi {
   OFFLOAD_ABI_ILP32
 };
 
+/* Types of memory optimization for an offload device.  */
+enum offload_memory {
+  OFFLOAD_MEMORY_NONE,
+  OFFLOAD_MEMORY_UNIFIED,
+  OFFLOAD_MEMORY_PINNED
+};
+
 /* Types of profile update methods.  */
 enum profile_update {
   PROFILE_UPDATE_SINGLE,
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 3e2f9bd5b4b..a368d80a123 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -202,7 +202,7 @@ in the following sections.
 -fno-builtin  -fno-builtin-@var{function}  -fcond-mismatch
 -ffreestanding  -fgimple  -fgnu-tm  -fgnu89-inline  -fhosted
 -flax-vector-conversions  -fms-extensions
--foffload=@var{arg}  -foffload-options=@var{arg}
+-foffload=@var{arg}  -foffload-options=@var{arg} -foffload-memory=@var{arg}
 -fopenacc  -fopenacc-dim=@var{geom}
 -fopenmp  -fopenmp-simd  -fopenmp-target-simd-clone@r{[}=@var{device-type}@r{]}
 -fpermitted-flt-eval-methods=@var{standard}
@@ -2779,6 +2779,20 @@ Typical command lines are
 -foffload-options=amdgcn-amdhsa=-march=gfx906
 @end smallexample
 
+@opindex foffload-memory
+@cindex OpenMP offloading memory modes
+@item -foffload-memory=none
+@itemx -foffload-memory=unified
+@itemx -foffload-memory=pinned
+Enable a memory optimization mode to use with OpenMP.  The default behavior,
+@option{-foffload-memory=none}, is to do nothing special (unless enabled via
+a requires directive in the code).  @option{-foffload-memory=unified} is
+equivalent to @code{#pragma omp requires unified_shared_memory}.
+@option{-foffload-memory=pinned} forces all host memory to be pinned (this
+mode may require the user to increase the ulimit setting for locked memory).
+All translation units must select the same setting to avoid undefined
+behavior.
+
 @opindex fopenacc
 @cindex OpenACC accelerator programming
 @item -fopenacc