[PATCH] D76278: [AMDGPU] Don't mark the .note section as ALLOC

[Sebastian Neubauer via Phabricator via llvm-commits]

Flakebi created this revision.
Flakebi added reviewers: arsenm, nhaehnle, kzhuravl, msearles.
Herald added subscribers: llvm-commits, kerbowa, hiraditya, t-tye, Anastasia, tpr, dstuttard, yaxunl, wdng, jvesely.
Herald added a project: LLVM.

Marking a section as ALLOC tells the ELF loader to load the section into memory.
As we do not want to load the notes into VRAM, the flag should not be there.

On AMDHSA, .note is still marked as ALLOC, apparently this is currently
needed for OpenCL (see https://reviews.llvm.org/D74995).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76278

Files:
  llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
  llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
  llvm/test/CodeGen/AMDGPU/amdpal-elf.ll


Index: llvm/test/CodeGen/AMDGPU/amdpal-elf.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/amdpal-elf.ll
@@ -0,0 +1,33 @@
+; RUN: llc < %s -mtriple=amdgcn--amdpal -mcpu=kaveri -filetype=obj -mattr=-code-object-v3 | llvm-readobj -symbols -s -sd | FileCheck --check-prefix=ELF %s
+; RUN: llc < %s -mtriple=amdgcn--amdpal -mcpu=kaveri -mattr=-code-object-v3 | llvm-mc -filetype=obj -triple amdgcn--amdpal -mcpu=kaveri -mattr=-code-object-v3 | llvm-readobj -symbols -s -sd | FileCheck %s --check-prefix=ELF
+; RUN: llc < %s -mtriple=amdgcn--amdpal -mcpu=gfx1010 -mattr=+WavefrontSize32,-WavefrontSize64,-code-object-v3 | FileCheck --check-prefix=GFX10-W32 %s
+; RUN: llc < %s -mtriple=amdgcn--amdpal -mcpu=gfx1010 -mattr=-WavefrontSize32,+WavefrontSize64,-code-object-v3 | FileCheck --check-prefix=GFX10-W64 %s
+
+; ELF: Section {
+; ELF: Name: .text
+; ELF: Type: SHT_PROGBITS (0x1)
+; ELF: Flags [ (0x6)
+; ELF: SHF_ALLOC (0x2)
+; ELF: SHF_EXECINSTR (0x4)
+; ELF: }
+
+; ELF: SHT_NOTE
+; ELF: Flags [ (0x0)
+; ELF: ]
+
+; ELF: Symbol {
+; ELF: Name: simple
+; ELF: Size: 36
+; ELF: Section: .text (0x2)
+; ELF: }
+
+; GFX10-W32: NumSGPRsForWavesPerEU: 4
+; GFX10-W32: NumVGPRsForWavesPerEU: 3
+; GFX10-W64: NumSGPRsForWavesPerEU: 2
+; GFX10-W64: NumVGPRsForWavesPerEU: 3
+
+define amdgpu_kernel void @simple(i32 addrspace(1)* %out) {
+entry:
+  store i32 0, i32 addrspace(1)* %out
+  ret void
+}
Index: llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
===================================================================
--- llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
+++ llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
@@ -133,6 +133,7 @@
 
 class AMDGPUTargetELFStreamer final : public AMDGPUTargetStreamer {
   MCStreamer &Streamer;
+  Triple::OSType Os;
 
   void EmitNote(StringRef Name, const MCExpr *DescSize, unsigned NoteType,
                 function_ref<void(MCELFStreamer &)> EmitDesc);
Index: llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
+++ llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
@@ -395,7 +395,7 @@
 
 AMDGPUTargetELFStreamer::AMDGPUTargetELFStreamer(
     MCStreamer &S, const MCSubtargetInfo &STI)
-    : AMDGPUTargetStreamer(S), Streamer(S) {
+    : AMDGPUTargetStreamer(S), Streamer(S), Os(STI.getTargetTriple().getOS()) {
   MCAssembler &MCA = getStreamer().getAssembler();
   unsigned EFlags = MCA.getELFHeaderEFlags();
 
@@ -438,9 +438,13 @@
 
   auto NameSZ = Name.size() + 1;
 
+  unsigned NoteFlags = 0;
+  if (Os == Triple::AMDHSA)
+    NoteFlags = ELF::SHF_ALLOC;
+
   S.PushSection();
   S.SwitchSection(Context.getELFSection(
-    ElfNote::SectionName, ELF::SHT_NOTE, ELF::SHF_ALLOC));
+    ElfNote::SectionName, ELF::SHT_NOTE, NoteFlags));
   S.emitInt32(NameSZ);                                        // namesz
   S.emitValue(DescSZ, 4);                                     // descz
   S.emitInt32(NoteType);                                      // type


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